Exam 7: Introduction to T Tests: Single Sample and Dependent Means

Which of the following statements about degrees of freedom is TRUE?

When conducting a t test for dependent means,μM

Testing participants before and after an experimental manipulation is called a(n)__________ design.

The most likely way for a t test to be presented in a research article for a study with 25 participants is

The symbol S²_M represents the __________.

Which of the following statements is true about t distributions?

Which of the following is an assumption for the t test for dependent means?

If the mean of a sample is 95,the mean of Population 2 is 75,and the standard deviation of the distribution of means is 5,the t score resulting from a t test for a single sample is __________.(Give a number.)

An organizational psychologist is hired as a consultant to a company planning to open a coffee house for college students.The company wants to know if their customers will drink more coffee if the coffee house is decorated in a Paris motif or in a San Francisco motif,so the psychologist sets up two similar rooms with the two motifs.Eight students spend an afternoon in each room,drinking all the coffee they like.The order in which they sit in the rooms is rotated so that half spend their first afternoon in the Paris room and half in the San Francisco room.The amount of coffee each participant drinks in each room is shown below.Using the .05 significance level,is there a significant difference between the numbers of cups of coffee consumed in the two rooms? a.Use the five steps of hypothesis testing. b.Sketch the distributions involved. c.Figure the effect size and find the approximate power of this study. d.Explain the logic of what you did to a person who is familiar with hypothesis testing with a known population variance and a single sample,including understanding decision errors,effect size and power,but who knows nothing about t tests of any kind (for example,you do not need to describe the steps or logic of hypothesis testing).Be sure you explain how this problem differs from a problem with a known population variance and a single sample.Your answer should consist mainly of a thorough explanation of the characteristics of the comparison distribution and all the figuring you did to determine those characteristics.

A counseling psychologist developing a technique to reduce procrastination has students time their procrastination for a week and uses this as a pretest measure of procrastination. Students then attend a workshop in which they are instructed to do a specific warm-up exercise for studying by focusing on a pleasant activity. Students again time their procrastination for a week, and the time from this second week is the posttest measure. -If the psychologist wants to see if there is a change (increase or decrease)in procrastination by 10 of the students who attended his workshop using the .05 significance level,the cutoff t score(s)would be

The main difference between a Z score and a t score is that

If a sample includes 27 people,the degrees of freedom used in the formula to estimate the population variance would be

Difference scores are computed for

based on the following table from a research article. -Which of the following statements is most likely to be true based on the results presented?

A school psychologist is using a depression inventory—on which a score of 0 indicates no depression and a score of 10 indicates severe depression—to see if the level of depression in fourth graders in a particular class of 20 students differs from that of fourth graders in general at a school. The results of previous testing indicate that fourth graders at the school usually have a score of 5 on the scale, but the variation is unknown. The current sample of 20 fifth graders has a mean depression score of 4.4. -The psychologist tests the null hypothesis that the level of depression of fourth graders in this class does not differ from fourth graders in general at the school and obtains a t score of -0.20.The decision regarding the null hypothesis would be to

A t test for a single sample would be used to compare

An industrial psychologist consulting with a chain of music stores knows that the average number of complaints management receives each month throughout the industry is 4,but the variance is unknown.Nine of the chain's stores were randomly selected to record complaints for one month; they received 2,4,3,5,0,2,5,1,and 5 complaints.Using the .05 significance level,is the number of complaints received by the chain different from the number of complaints received by music stores in general? a.Use the five steps of hypothesis testing. b.Sketch the distributions involved. c.Explain the logic of what you did to a person who is familiar with hypothesis testing with a known population variance and a single sample,but who knows nothing about t tests of any kind (for example,you do not need to describe the steps or logic of hypothesis testing).Be sure you explain how this problem differs from a problem with a known population variance and a single sample.Your answer should consist mainly of a thorough explanation of the characteristics of the comparison distribution and all the figuring you did to determine those characteristics.

When figuring the variance of the distribution of means based on an estimated population variance,you divide the estimated population variance by __________.

A swimming school claimed that the average seven-year-old would be able to swim across an Olympic-sized pool in less than 2 minutes after taking lessons from their instructors.To test this claim,a consumer psychologist arranged for eight randomly selected seven-year-old children to take lessons at the school and recorded how long it took each child to swim across a pool at the end of the lessons.The times (in seconds)were 60,120,110,80,70,90,100,and 130.What conclusion would the psychologist draw following a t test for a single sample using 120 seconds as the "known" population mean and the .05 significance level? a.Use the five steps of hypothesis testing. b.Sketch the distributions involved. c.Explain the logic of what you did to a person who is familiar with hypothesis testing with a known population variance and a single sample,but who knows nothing about t tests of any kind (for example,you do not need to describe the steps or logic of hypothesis testing).Be sure you explain how this problem differs from a problem with a known population variance and a single sample.Your answer should consist mainly of a thorough explanation of the characteristics of the comparison distribution and all the figuring you did to determine those characteristics.

Your professor asks you to update a manuscript with the results of a t test for dependent means and provides you with the following information: there were 19 people in the study,the t score was 4.36,and the result was significant at the .01 level.The best way to present this information would be