Deck 11: Experiments and Observational Studies

Question 1

Researchers reported that unmarried men are more likely to suffer from clinical depression than married men.These findings were based on the marriage histories of 700 men suffering from depression and 600 men not suffering from depression.

A)Prospective observational study
B)Retrospective observational study
C)Experiment

Answer 1

Retrospective observational study

Question 2

At a hospital in 1998,674 women were diagnosed with breast cancer.Five years later,88% of the Caucasian women and 83% of the African American women were still alive.Determine the nature and scope of the conclusion the study can reach.

A)Since there is no random assignment,there is no way to know that being Caucasian causes women with breast cancer an increased chance of surviving five years; there may have been lurking variables.
B)For Caucasian and African American women with breast cancer,attending St.Luke's hospital causes an increased chance of surviving five years.
C)Since there is no random assignment,there is no way to know that being Caucasian causes women with breast cancer an increased chance of surviving five years; there may have been confounding variables.
D)Since the study is limited to Caucasian and African American women,no conclusion can be reached.
E)For women with breast cancer,being Caucasian causes an increased chance of surviving five years.

Answer 2

Since there is no random assignment,there is no way to know that being Caucasian causes women with breast cancer an increased chance of surviving five years; there may have been lurking variables.

Question 3

400 patients suffering from chronic back pain were randomly assigned to one of two groups.Over a four-month period,the first group received acupuncture treatments and the second group received a placebo.Patients who received acupuncture treatments improved more than those who received the placebo.

A)Retrospective observational study
B)Experiment
C)Prospective observational study

Answer 3

Experiment

Question 4

A researcher wants to investigate the effectiveness of a cholesterol-lowering medication.The 450 participants are first divided into two groups - those suffering from diabetes and those not suffering from diabetes.Within each group the participants are randomly assigned to one of three groups.The first group will receive a low dose of the medication,the second group will receive a high dose of the medication,and the third group will receive a placebo.At the end of a six-month period,each person's cholesterol will be tested and the change in their cholesterol level will be recorded.The experiment is double blind.Within the group suffering from diabetes,those taking a high dose of the medication showed a marked decrease in their cholesterol level.Determine the nature and scope of the conclusion the experiment can reach.

A)Since the technicians administering the treatment could have been biased,no conclusion can be reached.
B)Since the physicians evaluating the results could have been biased,no conclusion can be reached.
C)A high dose of the medication may decrease cholesterol levels.
D)For people suffering from diabetes,a high dose of the medication may decrease cholesterol levels.
E)People suffering from diabetes may experience a decrease in cholesterol levels.

Question 5

780 patients suffering from high blood pressure were randomly assigned to one of three groups.Over a four-month period,the first group received an experimental drug,the second group received a placebo,and the third group received no treatment.The diastolic blood pressure of each participant was measured at the beginning and at the end of the period and the change in blood pressure was recorded.The biggest decrease in blood pressure was for those who received the drug.

A)Retrospective observational study
B)Prospective observational study
C)Experiment

Question 6

An examination of the medical records of 10,000 women who died between 1990 and 2000 showed that those who had taken steroids had a higher risk of osteoporosis.Identify the subjects studied.

A)Women who had taken steroids
B)Women who suffered from osteoporosis
C)Women who died between 1990 and 2000
D)Women who died between 1990 and 2000 and who had suffered from osteoporosis
E)Women who died between 1990 and 2000 and who had taken steroids

Question 7

Researchers reported that unmarried men are more likely to suffer from clinical depression than married men.These findings were based on the marriage histories of 700 men suffering from depression and 600 men not suffering from depression.Determine the nature and scope of the conclusion the study can reach.

A)Since there is no random assignment,there is no way to know that being unmarried increases the risk of depression; there may have been lurking variables.
B)Since the study involved only men,there is no way to know that being unmarried increases the risk of depression.
C)For men,getting married will result in a decreased risk of depression.
D)For American men,getting married will result in a decreased risk of depression.
E)Since there is no random assignment,there is no way to know that being unmarried increases the risk of depression; there may have been confounding variables.

Question 8

In a clinical trial,780 participants suffering from high blood pressure were randomly assigned to one of three groups.Over a one-month period,the first group received a low dosage of an experimental drug,the second group received a high dosage of the drug,and the third group received a placebo.The diastolic blood pressure of each participant was measured at the beginning and at the end of the period and the change in blood pressure was recorded.The biggest decrease in blood pressure was for those who received the low dosage of the drug.Identify the response variable measured.

A)The participants in the experiment
B)The dosage of the drug
C)The treatment received (placebo,low dosage,high dosage)
D)The one-month period
E)Change in diastolic blood pressure

Question 9

Among a group of men who were tracked for ten years,those who had scored over 130 on intelligence tests were more likely to suffer severe depression than those who had scored below 130 on intelligence tests.

A)Prospective observational study
B)Retrospective observational study
C)Experiment

Question 10

Among a group of Canadian men who were tracked for ten years,those who had scored over 130 on intelligence tests were more likely to suffer severe depression than those who had scored below 130 on intelligence tests.Identify the parameter of interest.

A)Nationality
B)Score on intelligence test
C)Gender
D)Risk of suffering from severe depression
E)Number of years since last episode of severe depression

Question 11

An educational researcher used school records to determine that,in one school district,84% of children living in two-parent homes graduated high school while 75% of children living in single-parent homes graduated high school.

A)Prospective observational study
B)Retrospective observational study
C)Experiment

Question 12

An employer suspects that on Mondays the percentage of employees absent from work is higher than on other days.Design a way he could find out whether there is any merit to his belief.Should he use an experiment or an observational study? He would like to have the information as soon as possible.

Question 13

A researcher wished to assess the importance of exercise in weight-loss programs.412 people,all considered to be at least 20 pounds overweight,were randomly assigned to one of two groups.Over a two-month period,the first group followed a particular diet but were instructed to perform no exercise other than walking.The second group followed the same diet but also performed aerobic exercise for one hour each day.At the end of the two months,the weight loss of each participant was recorded.The average weight loss for the second group was greater than the average weight loss for the first group.

A)Prospective observational study
B)Experiment
C)Retrospective observational study

Question 14

780 men suffering from high blood pressure were randomly assigned to one of two groups.Over a four-month period,the first group received an experimental drug and the second group received a placebo.A larger decrease in diastolic blood pressure was observed for those who received the drug.The experiment was double-blind.Determine the nature and scope of the conclusion the study can reach.

A)Since the technicians administering the treatment could have been biased,no conclusion can be reached.
B)Since the physicians evaluating the results could have been biased,no conclusion can be reached.
C)For men suffering from high blood pressure,the drug appears to lower diastolic blood pressure.
D)Since there is no random assignment,there is no way to know that the drug caused the decrease in diastolic blood pressure; there could have been confounding variables.
E)For adults suffering from high blood pressure,the drug appears to lower diastolic blood pressure.

Question 15

An examination of the medical records of 10,000 women who died between 1990 and 2000 showed that those who had taken steroids had a higher risk of osteoporosis.Identify the parameter of interest.

A)Year of death
B)Years of steroids use
C)Cause of death
D)Gender
E)Risk of osteoporosis

Question 16

An examination of the medical records of 10,000 women showed that those who were short and fair skinned had a higher risk of osteoporosis.

A)Prospective observational study
B)Retrospective observational study
C)Experiment

Question 17

780 men suffering from high blood pressure were randomly assigned to one of three groups.Over a four-month period,the first group received a low dosage of an experimental drug,the second group received a high dosage of the drug,and the third group received a placebo.The biggest decrease in blood pressure was for those who received the low dosage of the drug.Identify the subjects studied.

A)The treatment received (placebo,low dosage,high dosage)
B)Change in diastolic blood pressure
C)The dosage of the drug
D)Adults suffering from high blood pressure
E)Men suffering from high blood pressure

Question 18

Among a group of Canadian men who were tracked for ten years,those who had scored over 130 on intelligence tests were more likely to suffer severe depression than those who had scored below 130 on intelligence tests.Identify the subjects studied.

A)Canadian men suffering from depression
B)Canadian men who did not score over 130 on intelligence tests
C)Canadian men
D)Canadian men who scored over 130 on intelligence tests and who were suffering from depression
E)Canadian men who scored over 130 on intelligence tests

Question 19

A researcher wants to examine the effect of fertilizer and the effect of sunlight on the yield of tomatoes.She bought 60 tomato plants at a local garden store.She randomly assigned 30 tomato plants to be planted on the sunny side of the hill and 30 to be planted on the shady side.Within each group of 30 plants,she randomly assigned plants to one of three groups.The first group is grown with no fertilizer,the second group with a small amount of fertilizer,and the third group with a large amount of fertilizer.All tomato plants are planted at the same time and are all treated alike (in terms of how much they are watered,weeded etc).Each plant is grown to maturity.The total weight of tomatoes obtained from each plant is recorded.The person evaluating the results does not know which tomatoes received fertilizer or which were grown on the sunny side.Within both groups (those grown on the sunny side and those grown on the shady side)tomatoes grown with a large amount of fertilizer yielded the most tomatoes.Determine the nature and scope of the conclusion the experiment can reach.

A)Since the person evaluating the results could have been biased,no conclusion can be reached.
B)Yield may be increased for tomatoes grown with a large amount of fertilizer.
C)For tomatoes grown on the sunny side,yield may be increased for tomatoes grown with a large amount of fertilizer.
D)Since the technician tending to the plants could have been biased,no conclusion can be reached.
E)Yield may be increased for tomatoes grown on the sunny side with a large amount of fertilizer.

Question 20

An educational researcher used school records to determine that in the year 2000 in one school district,84% of children living in two-parent homes graduated high school while 75% of children living in single-parent homes graduated high school.Determine the parameter of interest.

A)Percentage of children living in two-parent homes
B)Year of high school graduation
C)High school graduation rate
D)Type of home (single or two-parent)
E)School district

Question 21

In an experiment,explain the difference between the treatments and the factors.

Question 22

A researcher wants to investigate the effectiveness of a cholesterol-lowering medication.The 450 participants are first divided into two groups - those suffering from diabetes and those not suffering from diabetes.Within each group the participants are randomly assigned to one of three groups.The first group will receive a low dose of the medication,the second group will receive a high dose of the medication,and the third group will receive a placebo.At the end of a six-month period,each person's cholesterol will be tested and the change in their cholesterol level will be recorded.Identify the treatments.

A)Medication (3 levels),change in cholesterol
B)Placebo,low dose of medication,high dose of medication (3 levels)
C)Medication (3 levels),diabetes (2 levels)
D)Placebo and diabetes,low dose of medication and diabetes,high dose of medication and diabetes,placebo and no diabetes,low dose of medication and no diabetes,high dose of medication and no diabetes (6 levels)
E)Medication (3 levels),blocking variable - diabetes (2 levels)

Question 23

A manufacturer of tennis rackets has designed a new racket and would like to compare it to their previous design.Suggest an appropriate experiment.

Question 24

A researcher wants to examine the effect of fertilizer and the effect of sunlight on the yield of tomatoes.She bought 60 tomato plants at a local garden store.She randomly assigned 30 tomato plants to be planted on the sunny side of the hill and 30 to be planted on the shady side.The 30 plants which are planted on the shady side are randomly assigned to one of three groups.The first group is grown with no fertilizer,the second group with a small amount of fertilizer,and the third group with a large amount of fertilizer.The 30 plants which are planted on the sunny side are likewise randomly assigned to one of three groups.The first group is grown with no fertilizer,the second group with a small amount of fertilizer,and the third group with a large amount of fertilizer.All tomato plants are planted at the same time and are all treated alike (in terms of how much they are watered,weeded etc.).Each plant is grown to maturity.The total weight of tomatoes obtained from each plant is recorded.

A)Completely randomized over two factors (fertilizer and location)
B)Completely randomized over one factor (fertilizer)
C)Randomized block design,blocking on fertilizer,with one factor,location
D)Blocked by fertilizer,blocked by location
E)Randomized block design,blocking on location,with one factor,fertilizer

Question 25

A researcher would like to investigate whether people suffering from insomnia can be helped by taking regular yoga classes or by reducing their intake of caffeine.Design an appropriate experiment.Be sure to identify the factors,levels,treatments,and response variable.

Question 26

A researcher wants to examine the effect of fertilizer and the effect of sunlight on the yield of tomatoes.She bought 60 tomato plants at a local garden store.She randomly assigned 30 tomato plants to be planted on the sunny side of the hill and 30 to be planted on the shady side.The 30 plants which are planted on the shady side are randomly assigned to one of three groups.The first group are grown with no fertilizer,the second group with a small amount of fertilizer,and the third group with a large amount of fertilizer.The 30 plants which are planted on the sunny side are likewise randomly assigned to one of three groups.The first group are grown with no fertilizer,the second group with a small amount of fertilizer and the third group with a large amount of fertilizer.All tomato plants are planted at the same time and are all treated alike (in terms of how much they are watered,weeded etc).Each plant is grown to maturity.The total weight of tomatoes obtained from each plant is recorded.Identify the factor(s)and the number of levels for each.

A)Fertilizer (3 levels),location (2 levels)
B)No fertilizer and sunny,small amount of fertilizer and sunny,large amount of fertilizer and sunny,no fertilizer and shady,small amount of fertilizer and shady,large amount of fertilizer and shady (6 levels)
C)No fertilizer,small amount of fertilizer,large amount of fertilizer (3 levels)
D)Sunny,shady (2 levels)
E)Fertilizer (3 levels),blocking variable - location (2 levels)

Question 27

A researcher wants to examine the effect of fertilizer and the effect of sunlight on the yield of tomatoes.She bought 60 tomato plants at a local garden store.She randomly assigned 30 tomato plants to be planted on the sunny side of the hill and 30 to be planted on the shady side.The 30 plants which are planted on the shady side are randomly assigned to one of three groups.The first group are grown with no fertilizer,the second group with a small amount of fertilizer,and the third group with a large amount of fertilizer.The 30 plants which are planted on the sunny side are likewise randomly assigned to one of three groups.The first group are grown with no fertilizer,the second group with a small amount of fertilizer and the third group with a large amount of fertilizer.All tomato plants are planted at the same time and are all treated alike (in terms of how much they are watered,weeded etc).Each plant is grown to maturity.The total weight of tomatoes obtained from each plant is recorded.Identify the treatments.

A)No fertilizer,small amount of fertilizer,large amount of fertilizer
B)No fertilizer and sunny,small amount of fertilizer and sunny,large amount of fertilizer and sunny,no fertilizer and shady,small amount of fertilizer and shady,large amount of fertilizer and shady
C)Sunny,shady
D)Fertilizer,location
E)Fertilizer,blocking variable - location

Question 28

A researcher wants to investigate whether different forms of exercise can be used to help hyperactive children.A group of 90 children is divided into two groups according to age - those aged 9-12 and those aged 5-9.Within each age group the children are randomly assigned to one of three groups.The first group will just do their normal exercise.The second group will be given an additional exercise routine (moderate).The third group will be given an additional exercise routine (strenuous).At the end of a four month period parents will be asked to evaluate their children's progress.

A)Completely randomized over one factor (exercise)
B)Randomized block design,blocking on age,with one factor,exercise.
C)Randomized block design,blocking on exercise,with one factor,age
D)Completely randomized over two factors,exercise and age
E)None of the above

Question 29

A researcher wants to investigate the effectiveness of a cholesterol-lowering medication.The 450 participants are first divided into two groups - those suffering from diabetes and those not suffering from diabetes.Within each group the participants are randomly assigned to one of three groups.The first group will receive a low dose of the medication,the second group will receive a high dose of the medication,and the third group will receive a placebo.At the end of a six-month period,each person's cholesterol will be tested and the change in their cholesterol level will be recorded.

A)Completely randomized over two factors,medication and diabetes
B)Randomized block design,blocking on cholesterol level,with two factors,medication and diabetes
C)Randomized block design,blocking on diabetes,with one factor,medication
D)Randomized block design,blocking on medication,with one factor,diabetes
E)None of the above

Question 30

A researcher has developed a set of breathing exercises and would like to investigate whether they can help to reduce anxiety.She wonders whether the breathing exercises for 15 minutes or for 30 minutes would be more effective.Design an appropriate experiment.

Question 31

An exercise physiologist has designed two alternative training regimes which he hopes will enable middle distance runners to improve their times at the 800 metres.He wants to know which regime will work better.Design an experiment which will allow him to investigate this question.Assume that all the athletic coaches in a district are prepared to participate and assume that all athletes training with a particular coach will follow the same regime.Be sure to identify the factors,the levels,treatments,and response variable.

Question 32

A researcher would like to investigate whether people suffering from insomnia can be helped by taking yoga classes.She designs an experiment as follows.She will obtain a group of volunteers who are suffering from insomnia and who do not currently practice yoga.Each person's degree of insomnia at the start of the experiment will be evaluated.She will investigate whether yoga classes every day or three times per week are more effective.So the factor yoga will have 3 levels (no yoga,yoga three times a week,yoga every day).Each volunteer will choose which group they would like to be part of.At the end of a suitable time period,for example two months,each person's degree of insomnia will again be evaluated.The improvement for the three groups will then be compared.The person evaluating the insomnia levels will be blinded to which group the patients were in.Identify the flaw(s)in this experiment.

Question 33

An education researcher was interested in examining the effect of the teaching method and the effect of the teacher on students' scores on a reading test. Suppose there are four different teachers (Juliana, Felix, Sonia, and Helen) and three different teaching methods (A, B, and C). Students were randomly assigned to a teaching method and teacher. Those who studied with Sonia using method B achieved the highest scores.

A) Retrospective observational study
B) Prospective observational study
C) Experiment

Question 34

An ice cream company wants to introduce a new flavor.They are considering two possibilities - Mint Delight and Chocolate Fiesta.They want to know which one customers will prefer.Design an experiment to investigate this question.

Question 35

780 participants suffering from depression were randomly assigned to one of three groups.Over a four-month period,the first group received a low dosage of an experimental drug,the second group received a high dosage of the drug,and the third group received a placebo.At the end of the period each participant rated their mood on a scale of 1-10.Identify the factor(s)in the experiment and the number of levels for each.

A)The experimental drug (3 levels)
B)The dosage of the drug (3 levels)
C)The experimental drug (3 levels),mood (10 levels)
D)Mood (10 levels)
E)Placebo,low dosage,high dosage (3 levels)

Question 36

A medical researcher believes that supplements of glucosamine can help to reduce the pain of arthritis.She would like to test the supplement at two different dosage levels.Design an experiment to test the conjecture.Be sure to identify the factors,the levels,treatments,and response variable.

Question 37

A researcher wants to investigate whether different forms of exercise can be used to help hyperactive children.A group of 90 children is divided into two groups according to age - those aged 9-12 and those aged 5-9.Within each age group the children are randomly assigned to one of three groups.The first group will just do their normal exercise.The second group will be given an additional exercise routine (moderate).The third group will be given an additional exercise routine (strenuous).At the end of a four month period parents will be asked to evaluate their children's progress.Identify the treatments.

A)Exercise,age
B)Age 5-9,age 9-12
C)Normal exercise and age 5-9,additional exercise (moderate)and age 5-9,additional exercise (strenuous)and age 5-9,normal exercise and age 9-12,additional exercise (moderate)and age 9-12,additional exercise (strenuous)and age 9-12
D)Exercise,blocking variable - age
E)Normal exercise,additional exercise (moderate),additional exercise (strenuous)

Question 38

In a clinical trial,780 participants suffering from high blood pressure were randomly assigned to one of three groups.Over a one-month period,the first group received a low dosage of an experimental drug,the second group received a high dosage of the drug,and the third group received a placebo.The diastolic blood pressure of each participant was measured at the beginning and at the end of the period and the change in blood pressure was recorded.The biggest decrease in blood pressure was for those who received the low dosage of the drug.

A)Completely randomized over one factor (diastolic blood pressure),blocked by experimental drug
B)Completely randomized over one factor (experimental drug)
C)Blocked by experimental drug,blocked by diastolic blood pressure
D)Completely randomized over one factor (experimental drug),blocked by diastolic blood pressure
E)Completely randomized over two factors (experimental drug,diastolic blood pressure)

Question 39

Explain the difference between an observational study and an experiment.

Question 40

780 participants suffering from depression were randomly assigned to one of three groups.Over a four-month period,the first group received a low dosage of an experimental drug,the second group received a high dosage of the drug,and the third group received a placebo.At the end of the period each participant rated their mood on a scale of 1-5.Identify the treatments.

A)The experimental drug,mood
B)Placebo,low dosage,high dosage
C)The dosage of the drug
D)Mood level 1,mood level 2,mood level 3,mood level 4,mood level 5
E)The experimental drug

Question 41

A medical researcher believes that supplements of glucosamine can help to reduce the pain of arthritis.She would like to test the supplement at two different dosage levels.She designs an experiment as follows to test her conjecture.She will obtain a group of volunteers who suffer from arthritis.Each patient's condition will be evaluated by a doctor at the start of the experiment.Volunteers will be randomly assigned to one of two groups.Each day for the duration of the experiment,patients in group 1 will receive a low dose of glucosamine and patients in group 2 will receive a higher dose of glucosamine.After a suitable amount of time (two months,for example),the doctor will evaluate each patient's progress.Based on the amount of inflammation and the patient's report on the amount of pain,the doctor will give each patient a numerical score to represent their improvement.She would then compare the amount of improvement for the two groups.Also,she will ensure that the evaluating doctor and the technicians administering the supplements are blinded to whether patients receive a low dose or high dose.Identify the flaw(s)in this experiment.

Question 42

A researcher would like to investigate whether people suffering from insomnia can be helped by taking yoga classes.She designs an experiment as follows.She will obtain a group of volunteer insomniacs who do not currently practice yoga.Each person's degree of insomnia at the start of the experiment will be evaluated.Volunteers will be randomly assigned to one of three groups.Those in group 1 will practice yoga every day,those in group 2 will practice 3 times per week,and those in group 3 will not practice yoga.At the end of a suitable time period each person's degree of insomnia will again be evaluated.The improvement for the three groups will then be compared.Explain why it is important to assign volunteers to groups at random rather than letting them choose their own group.

Question 43

An education researcher wishes to assess the effectiveness of three different methods for teaching young children to read.The 380 children participating in the study are divided into three groups.The study runs for six months.The children in the first group are taught using method A,the children in the second group are taught using method B,and the children in the third group are taught using method C.At the end of the six months,the reading ability of the children in the different groups is assessed.Why is it important to use random assignment when dividing the children into three groups?

Question 44

An education researcher was interested in examining the effect of the teaching method and the teacher on students' reading levels. 257 students participated in an experiment. There were two different teachers (Juliana and Felix) and three different teaching methods (A, B, and C). Students were randomly assigned to a teaching method and teacher. At the end of the semester the students took a reading test on which they received a score out of 20. Students who studied with Felix using method B achieved the highest scores. The person evaluating the results does not know which teacher or teaching method the students were assigned to.

A) Double blind
B) Single blind
C) Neither

Question 45

A medical researcher believes that supplements of glucosamine can help to reduce the pain of arthritis.She designs an experiment as follows.She will obtain a group of volunteers who suffer from arthritis.Each patient's condition will be evaluated by a doctor at the start of the experiment.Volunteers will be randomly assigned to one of three groups.Each day patients in group 1 will receive a low dose of glucosamine,patients in group 2 a higher dose of glucosamine,and patients in group 3 a placebo.After a suitable amount of time,for example two months,the doctor will evaluate each patient's progress.Based on the amount of inflammation and the patient's report on the amount of pain,the doctor will give each patient a numerical score to represent their improvement.The researcher will then compare the improvement for the three groups.The evaluating doctor will be blinded to patients' treatments.If the result is found to be statistically significant,what would that mean in this case?

Question 46

A pharmaceutical company has developed a medication which they believe will help to reduce the pain of arthritis.They would like to test the medication at two different dosage levels.They design an experiment as follows to test the medication.They will obtain a group of volunteers who suffer from arthritis.A doctor from the pharmaceutical company will evaluate each patient's condition at the start of the experiment.Volunteers will be randomly assigned to one of three groups.Each day for the duration of the experiment,patients in group 1 will receive a low dose of the medication,patients in group 2 will receive a higher dose of the medication,and patients in group 3 will receive a placebo.After a suitable amount of time (two months,for example),the same doctor will evaluate each patient's progress.Based on the amount of inflammation and the patient's report on the amount of pain,the doctor will give each patient a numerical score to represent their improvement.The amount of improvement for the three groups will then be compared.The researchers will have the technicians administering the medication blinded to whether patients receive a low dose,a high dose,or a placebo.Identify the most serious flaw in this experiment.

A)There could be lurking variables.
B)The volunteers should have been randomly selected.
C)The doctor should choose the best treatment for each patient,instead of allowing volunteers to be assigned at random to a treatment.
D)The experiment is only single blind.The doctor evaluating the patients' progress is not blind to which treatment patients received.
E)There is no blocking.

Question 47

A researcher wants to examine the effect of fertilizer and the effect of sunlight on the yield of tomatoes.She bought 60 tomato plants at a local garden store.She randomly assigned 30 tomato plants to be planted on the sunny side of the hill and 30 to be planted on the shady side.Within each group of 30 plants,she randomly assigned plants to one of three groups.The first group is grown with no fertilizer,the second group with a small amount of fertilizer,and the third group with a large amount of fertilizer.All tomato plants are planted at the same time and each plant is grown to maturity.The total weight of tomatoes obtained from each plant is recorded.The person evaluating the results does not know which tomatoes received fertilizer or which were grown on the sunny side.

A)Single blind
B)Double blind
C)Neither

Question 48

A medical researcher believes that supplements of glucosamine can help to reduce the pain of arthritis.She would like to test the supplement at two different dosage levels.She designs an experiment as follows to test her conjecture.She will obtain a group of volunteers who suffer from arthritis.Each patient's condition will be evaluated by a doctor at the start of the experiment.Volunteers will be randomly assigned to one of two groups.Each day for the duration of the experiment,patients in group 1 will receive a low dose of glucosamine,patients in group 2 will receive a higher dose of glucosamine.After a suitable amount of time (two months,for example),the doctor will evaluate each patient's progress.Based on the amount of inflammation and the patient's report on the amount of pain,the doctor will give each patient a numerical score to represent their improvement.The amount of improvement for the two groups would then be compared.She will have the evaluating doctor and the technicians administering the supplements blinded to whether patients receive a low dose or high dose.Identify the most serious flaw in this experiment.

A)The experiment is not double blind; doctor evaluating the progress may be biased.
B)There is no placebo group.
C)Volunteers should have been selected randomly.
D)There could be lurking variables.
E)There is no blocking.

Question 49

A researcher has developed a set of breathing exercises and would like to investigate whether they can help to reduce anxiety.She designs an experiment as follows.She will obtain a group of volunteers suffering from anxiety.They will be given a test to measure the level of their anxiety.Volunteers will be randomly assigned to one of three groups.Those in group 1 will do breathing exercises for 15 minutes per day,those in group 2 will do breathing exercises for 30 minutes per day,and those in group 3 (control group)will do no breathing exercises.After a suitable time period,each person will again take the anxiety test.The researcher will compare the average change in score for the three groups.Is it possible to double blind this experiment? Explain.

Question 50

A statistics instructor has designed two different methods for teaching a statistics course and would like to investigate which is more effective.He designs an experiment as follows.He will obtain a group of 60 volunteer statistics students.
Volunteers will be randomly assigned to one of two groups.Group 1 will be taught the statistics course using method A and group 2 will be taught using method B.Other than the different methods,everything else will be similar for the two groups.For example,both groups will have the same teacher,the same lecture room,the same amount of time devoted to the course.At the end of the semester,students will all take the same test.Then the scores for the two groups will be compared.If the first group has a mean score of 67.7 with a standard deviation of 13.4 and the second group a mean score of 71.6 with a standard deviation of 11.2,do you think that this result is statistically significant? Explain.

Question 51

780 men suffering from high blood pressure were randomly assigned to one of two groups.Over a four-month period,the first group received an experimental drug and the second group received a placebo.A larger decrease in diastolic blood pressure was observed for those who received the drug.The patients did not know whether they were receiving the drug or the placebo.Neither the technicians administering the treatments nor the physicians evaluating the results knew which participants had received the drug and which the placebo.

A)Double blind
B)Single blind
C)Neither

Question 52

A double-blind experiment of an allergy medication is being tested on 100 participants according to this diagram: If Group 2 receives a full dose of the medication,what should Group 1's treatment consist of?

A)Blocked doses
B)A 50% dose
C)Stratified doses
D)A placebo
E)Randomized doses

Question 53

A researcher wants to investigate whether different forms of exercise can be used to help hyperactive children.A group of 90 children is divided into two groups according to age - those aged 9-12 and those aged 5-9.Within each age group the children are randomly assigned to one of three groups.The first group will just do their normal exercise.The second group will be given an additional exercise routine (moderate).The third group will be given an additional exercise routine (strenuous).At the end of a four month period parents will be asked to evaluate their children's progress.

A)Double blind
B)Single blind
C)Neither

Question 54

A medical researcher designs an experiment to test whether supplements of glucosamine can help to reduce the pain of arthritis.She will obtain a group of 90 volunteers who suffer from arthritis.Each patient's condition will be evaluated by a doctor at the start of the experiment.Volunteers will be randomly assigned to one of three groups.Each day patients in group 1 will receive a low dose of glucosamine,patients in group 2 will receive a higher dose of glucosamine,and patients in group 3 will receive a placebo.After a suitable amount of time,the doctor will evaluate each patient's progress.Based on the amount of inflammation and pain,the doctor will give each patient a numerical score to represent their improvement.The researcher will then compare the improvement for the three groups.Describe a strategy to randomly assign the 90 volunteers to the three treatments.

Question 55

A manufacturer of tennis rackets would like to test their new racket.The company sponsors 10 tennis players who will be playing at Wimbledon.To test the racket,they have each player serve 30 times with their old racket.Then they have each player serve 30 times with the new racket.They compare the percentage of good serves with the two rackets.Identify the flaw(s)in this experiment and suggest some improvements.

Question 56

A researcher wants to investigate the effectiveness of a cholesterol-lowering medication.The 450 participants are first divided into two groups - those suffering from diabetes and those not suffering from diabetes.Within each group the participants are randomly assigned to one of three groups.The first group will receive a low dose of the medication,the second group will receive a high dose of the medication,and the third group will receive a placebo.At the end of a six-month period,each person's cholesterol will be tested and the change in their cholesterol level will be recorded.Identify the factor(s)and any blocking variables and the number of levels for each.

A)Factor: Medication (3 levels),Factor: diabetes (2 levels)
B)Factor: Diabetes,no diabetes (2 levels)
C)Factor: Medication (3 levels),Blocking variable: diabetes (2 levels)
D)Factor: Placebo,low dose of medication,high dose of medication (3 levels)
E)Factor: Placebo and diabetes,low dose of medication and diabetes,high dose of medication and diabetes,placebo and no diabetes,low dose of medication and no diabetes,high dose of medication and no diabetes (6 levels)

Question 57

A pharmaceutical company will be testing a new "one-dosage fits all" medication for treating depression.The pharmaceutical company has 100 willing test subjects that will undergo a 30-day,double-blind experiment.The experiment uses the following diagram as a guide for administering the medication at various doses,from 5% to 125%. What is the most obvious factor missing from this proposed experiment?

A)A control group
B)A 100% dosage
C)Stratifying must be used.
D)Blocking must be used.
E)Nothing is missing.Basic variations have been accounted for.

Question 58

A researcher would like to investigate whether people suffering from insomnia can be helped by taking yoga classes.She designs an experiment as follows.She will obtain a group of volunteers who are suffering from insomnia and who do not currently practice yoga.Each person's degree of insomnia at the start of the experiment will be evaluated.She will investigate whether yoga classes every day or three times per week are more effective.So the factor yoga will have 3 levels (no yoga,yoga three times a week,yoga every day).Each volunteer will choose which group they would like to be part of.At the end of a suitable time period,for example two months,each person's degree of insomnia will again be evaluated.The improvement for the three groups will then be compared.The person evaluating the insomnia levels will be blinded to which group the patients were in.Identify the most serious flaw in this experiment.

A)The volunteers were not selected randomly.
B)The person evaluating the insomnia levels could have been biased.
C)There was no placebo group.
D)There was no blocking.
E)Volunteers chose their treatment instead of being randomly assigned to one of the groups.

Question 59

A researcher wants to investigate whether different forms of exercise can be used to help hyperactive children.A group of 90 children is divided into two groups according to age - those aged 9-12 and those aged 5-9.Within each age group the children are randomly assigned to one of three groups.The first group will just do their normal exercise.The second group will be given an additional exercise routine (moderate).The third group will be given an additional exercise routine (strenuous).At the end of a four-month period,parents will be asked to evaluate their children's progress.Identify the factor(s)and any blocking variables and the number of levels for each.

A)Factor: exercise (3 levels),Blocking variable: age (2 levels)
B)Blocking variable: exercise (3 levels),Factor: age (2 levels)
C)Factor: exercise (3 levels),Factor: age (2 levels)
D)Normal exercise and age 5-9,additional exercise (moderate)and age 5-9,additional exercise (strenuous)and age 5-9,normal exercise and age 9-12,additional exercise (moderate)and age 9-12,additional exercise (strenuous)and age 9-12 (6 levels)
E)Factor: Normal exercise,additional exercise (moderate),additional exercise (strenuous)(3 levels)

Question 60

A pharmaceutical company has developed a medication which they believe will help to reduce the pain of arthritis.They would like to test the medication at two different dosage levels.They design an experiment as follows to test the medication.They will obtain a group of volunteers who suffer from arthritis.A doctor from the pharmaceutical company will evaluate each patient's condition at the start of the experiment.Volunteers will be randomly assigned to one of three groups.Each day for the duration of the experiment,patients in group 1 will receive a low dose of the medication,patients in group 2 will receive a higher dose of the medication,and patients in group 3 will receive a placebo.After a suitable amount of time (two months,for example),the same doctor will evaluate each patient's progress.Based on the amount of inflammation and the patient's report on the amount of pain,the doctor will give each patient a numerical score to represent their improvement.The amount of improvement for the three groups would then be compared.They will also ensure that the technicians administering the supplements are blinded to whether patients receive a low dose,a high dose,or a placebo.Identify the flaw(s)in this experiment.

Question 61

An educational researcher has designed two different methods for teaching a statistics course and would like to investigate which is more effective.He designs an experiment as follows.He will obtain a group of volunteer statistics students.Volunteers will be randomly assigned to one of two groups.Group 1 will be taught the statistics course by Anna Clark using method A and group 2 will be taught by Bob Beauman using method B.At the end of the semester,students will all take the same test.Then the scores for the two groups will be compared.The person grading the tests will be blinded to which group students were in.Identify the most serious flaw in this experiment.

A)There is a confounding variable - namely the teacher.
B)There is no blocking.
C)The person grading the tests may have been biased.
D)Since there is no random assignment,there could be lurking variables.
E)Volunteers should have been selected randomly.

Question 62

A manufacturer of tennis rackets has designed a new racket and would like to compare it to their previous design.They design an experiment as follows.They will obtain 100 volunteer tennis players.Volunteers will be randomly assigned to one of two groups.Group 1 will use the company's previous racket first and the new racket second.Group 2 will use the company's new racket first and the previous racket second.Each player will serve 100 times with each racket.The percentage of good serves with the two rackets will then be compared.The experiment is double blind.If the group of volunteers consists of 60 professional tennis players and 40 beginners,explain why blocking by tennis level would be important.

Question 63

A new type of pain reliever is administered to 30 consenting post-operative patients in various hospitals.Although the pain reliever has already been tested for safety and effectiveness,this experiment is to observe and categorize any side-effects.Because of maturity and body mass,it is decided to test the adults separately from the children. The grouping of the adults separate from the children is an example of what?

A)Stratifying
B)Controlling
C)Matching
D)Reduction of confounding factors
E)Blocking

Question 64

A manufacturer of tennis rackets has designed a new racket and would like to compare it to their previous design.The company obtains 100 volunteer tennis players.Volunteers are randomly assigned to one of two groups.Group 1 will use the company's previous racket first and the new racket second.Group 2 will use the new racket first and the previous racket second.Each player will serve 30 times with each racket.The percentage of good serves with the two rackets will then be compared.The players are blinded to which racket they are using.Also,the person recording the percentage of good serves is blinded to which racket the player is using.If the group of volunteers consists of 60 professional tennis players and 40 beginners,how could the experiment be improved?

Question 65

Researchers reported that going to the gym regularly increases your chance of finding a high paying job.These findings were based on incomes reported by 200 active members of a gym and 200 people who do not belong to a gym.Why is this conclusion not justified?

Question 66

An ice cream company wants to introduce a new flavor.They are considering two possibilities - Mint Delight and Chocolate Fiesta.They want to know which one customers will prefer.Design an experiment to investigate this question.The company feels that children may have different preferences than adults.Be sure to take that into account in the design of the experiment.

Question 67

A manufacturer of tennis rackets has designed a new racket and would like to investigate whether players will prefer it to their previous design.The company obtains 100 volunteer tennis players.Volunteers are randomly assigned to one of two groups.Group 1 will use the company's previous racket first and the new racket second.Group 2 will use the new racket first and the company's previous racket second.Each player will serve 30 times with each racket.Then the percentage of good serves with the two rackets will be compared.The players are blinded to which racket they are using.Also,the person recording the percentage of good serves is blinded to which racket the players use.If the group of volunteers consists of 50 professional tennis players and 50 beginners,how could the experiment be improved?

A)Have players choose their group instead of assigning them randomly to a group.
B)Use blocking - first divide the volunteers into professional tennis players and beginners.Within each block randomly assign volunteers to one of the two groups.
C)Include a placebo.
D)Use matching - match each professional player with a beginning player before assigning players to one of the two groups.
E)Add another factor - level of player,so that there will be four treatments: new racket and beginner,new racket and professional,previous racket and beginner,previous racket and professional.

Question 68

An educational researcher has designed two different methods for teaching a statistics course and would like to investigate which is more effective.He designs an experiment as follows.He will obtain a group of volunteer statistics students.
Volunteers will be randomly assigned to one of two groups.Group 1 will be taught the statistics course by Anna Clark using method A and group 2 will be taught by Bob Beauman using method B.At the end of the semester,students will all take the same test.Then the scores for the two groups will be compared.Identify the flaw(s)in this experiment and suggest a way of improving the experiment.

Question 69

A nutritionist has come up with a new diet that she believes will allow overweight people to lose weight more quickly than the diet she had previously prescribed for patients.She suspects that the new diet may be more effective for women than for men.Design an appropriate experiment.

Question 70

Researchers reported that for men,being unmarried increases the risk of depression.These findings were based on the medical records of 400 married men and 500 unmarried men.Why is this conclusion not justified?

Question 71

A researcher would like to compare the effectiveness of two competing study courses both of which claim to raise students' SAT scores.He would also like investigate whether students can benefit from listening to a certain type of music while they study.Design an appropriate experiment.Be sure to identify the factors,levels,treatments,and response variable.

Question 72

An agricultural researcher wishes to compare the yield of four different varieties of wheat.64 plots of land are available for an experiment.On each plot of land one of the varieties of wheat will be grown.At the end of the experiment the yield for the different varieties will be compared.32 of the plots are at one site (site

A)and the other 32 are at another site (site
B).The soil at site A differs significantly from the soil at site B.If the researcher wishes to design an experiment using randomized block design,how could the wheat varieties be assigned to the different plots?

Question 73

An agricultural researcher wishes to compare the yield of four different varieties of wheat.64 plots of land are available for an experiment.On each plot of land one of the varieties of wheat will be grown.At the end of the experiment the yield for the different varieties will be compared.32 of the plots are at one site (site

A)and the other 32 are at another site (site
B).The soil at site A differs significantly from the soil at site B.The researcher wishes to design an experiment.In this example,why might a randomized block design,with blocking by soil type,be preferable to a completely randomized design?

Question 74

In a clinical trial,each participant will receive a placebo,a low dosage of a drug,or a high dosage of the drug.The participants consist of 90 men and 90 women.The 90 men are randomly divided into three groups of 30.Each group of men is randomly assigned to a different treatment (placebo,low dose,or high dose).Likewise,the 90 women are randomly divided into three groups of 30.Each group of women is randomly assigned to a different treatment (placebo,low dose,or high dose).Is this a completely randomized design or a randomized block design? Explain your answer.

Question 75

The Asian longhorned beetle kills trees by burrowing within the trunk and branches and disrupting the sap flow.This beetle favors hardwood trees,such as maple,elm,and ash.A new pesticide will be tested in a major metropolitan city.A statistician designs an experiment for 200 mature maple trees and randomly assigns half of the trees to receive this new pesticide,and the rest of the trees receive a control treatment. Is there any obvious way to improve this experiment to evaluate the effectiveness of this new pesticide?

A)Yes,stratifying must be used.
B)Yes,blocking must be used.
C)No,basic variations have been accounted for.
D)Yes,matching must be used.
E)Yes,a placebo is missing.

Question 76

At a hospital in 1998,674 women were diagnosed with breast cancer.Five years later,88% of the Caucasian women and 83% of the African American women were still alive.A researcher concludes that being Caucasian causes women with breast cancer an increased chance of surviving five years.Why is this conclusion not justified?

Question 77

Researchers reported that for men,being unmarried increases the risk of depression.These findings were based on the medical records of 400 married men and 500 unmarried men.Since there is no random assignment,this conclusion is not justified because there may be lurking variables.Which of the following are possible lurking variables?
I: Rate of depression
II: Income
III: Type of employment
IV: Age
V: Gender

A)II,III,IV
B)III,IV
C)II,IV
D)II,III,IV,V
E)I,II,III

Question 78

At a hospital in 1998,674 women were diagnosed with breast cancer.Five years later,88% of the Caucasian women and 83% of the African American women were still alive.A researcher concludes that being Caucasian causes women with breast cancer an increased chance of surviving five years.Since there is no random assignment and there may have been lurking variables,this conclusion is not justified.Which of the following are possible lurking variables?
I: Income
II: Neighborhood where patient lives
III: Quality of health care
IV: Diet
V: Number of years surviving since diagnosis

A)I,II,III,IV,V
B)I,III,IV
C)I,IV
D)I,II,III,IV
E)II,IV

Question 79

An agricultural researcher wishes to compare the yield of four different varieties of wheat.64 plots of land are available for an experiment.On each plot of land one of the varieties of wheat will be grown.At the end of the experiment the yield for the different varieties will be compared.32 of the plots are at one site (site

A)and the other 32 are at another site (site
B).The soil at site A differs significantly from the soil at site B.If the researcher wishes to design an experiment using completely randomized design,how could the wheat varieties be assigned to the different plots?

Question 80

A clothing manufacturer is curious if celebrity endorsements will influence a customer's decision in buying its products.This clothing manufacturer premieres its latest series of commercials privately to two separate groups of potential shoppers.One group will see a series of commercials without celebrities,and one group will see a series of commercials with celebrities.Furthermore,the manufacturer decides to split up the male shoppers from the female shoppers. Grouping the shoppers together by gender is an example of what?

A)Stratifying
B)Matching
C)Reduction of confounding factors
D)Factoring
E)Blocking