Question 1

The interquartile range and semi-interquartile range are the same measure.

Accepted Answer

A) True 
 B)False

Question 2

A researcher decides to split scores on an exam into quartiles.She determines that a score of 64 is at the 25th percentile,a score of 74 is at the 50th percentile,and a score of 80 is at the 75th percentile.What is the interquartile range (IQR)for these data?

Accepted Answer

A)  16 
B)  10 
C)  6 
D)  There is not enough information to answer this question. 
A)  16 
B)  10 
C)  6 
D)  There is not enough information to answer this question.

Question 3

A researcher selects a sample of 24 participants and has them complete a survey on dating preferences.In this example,what are the degrees of freedom for sample variance and what does this represent?

Accepted Answer

A)  df = 24; it represents the number of scores that are free to vary in a sample. 
B)  df = 23; it represents the number of scores that are free to vary in a sample. 
C)  df = 23; dividing SS by df makes the sample variance a biased estimator of the population variance. 
D)  df = 24; dividing SS by df makes the sample variance an unbiased estimator of the population variance. 
A)  df = 24; it represents the number of scores that are free to vary in a sample. 
B)  df = 23; it represents the number of scores that are free to vary in a sample. 
C)  df = 23; dividing SS by df makes the sample variance a biased estimator of the population variance. 
D)  df = 24; dividing SS by df makes the sample variance an unbiased estimator of the population variance.

Question 4

The population standard deviation is equal to 10 when SS = 100 and n = 10.

Accepted Answer

A) True 
 B)False

Question 5

Which of the following distributions has the largest variability?

Accepted Answer

A)  scores: 1, 3, 6, 9, and 12 
B)  scores: 22, 24, 26, 28, and 30 
C)  scores: 2, 3, 4, 5, and 6 
D)  scores: 1, 2, 3, 4, and 5 
A)  scores: 1, 3, 6, 9, and 12 
B)  scores: 22, 24, 26, 28, and 30 
C)  scores: 2, 3, 4, 5, and 6 
D)  scores: 1, 2, 3, 4, and 5

Question 6

The standard deviation is typically reported in research reports with the mean for a data set.

Accepted Answer

A) True 
 B)False

Question 7

For a set of data that is normally distributed with 32 ± 4 (M ± SD),we know that at least 68% of the data will fall between scores of 28 and 36.

Accepted Answer

A) True 
 B)False

Question 8

A researcher records the sound (in decibels)during a series of lessons taught by a substitute teacher at a local elementary school.In his study,he found that the sound was 80 ± 6 (M ± SD)decibels.Assuming the data are normally distributed,which of the following is an appropriate conclusion?

Accepted Answer

A)  At least 68% of classes were between 76 and 84 decibels. 
B)  At least 5% of classes were louder than 68 decibels. 
C)  At least 95% of classes were between 68 and 92 decibels. 
D)  All of these. 
A)  At least 68% of classes were between 76 and 84 decibels. 
B)  At least 5% of classes were louder than 68 decibels. 
C)  At least 95% of classes were between 68 and 92 decibels. 
D)  All of these.

Question 9

All other things being equal,the value in the numerator is computed the same for sample variance and population variance.

Accepted Answer

A) True 
 B)False

Question 10

For nonnormal distributions,at least 99.7% of data will fall within three standard deviations of the mean.

Accepted Answer

A) True 
 B)False

Question 11

Which of the following is an example of a distribution with NO variability?

Accepted Answer

A)  scores: 3, 5, 4, 4, 5, and 3 
B)  scores: 5, 5, 5, 5, 5, and 5 
C)  scores: 1, 2, 3, 4, 5, and 6 
D)  None of these; all distributions have at least some variability greater than 0. 
A)  scores: 3, 5, 4, 4, 5, and 3 
B)  scores: 5, 5, 5, 5, 5, and 5 
C)  scores: 1, 2, 3, 4, 5, and 6 
D)  None of these; all distributions have at least some variability greater than 0.

Question 12

The advantage of squaring the deviation of each score from the mean and then summing is that

Accepted Answer

A)  it makes the sample variance an unbiased estimator of the population variance. 
B)  it makes the degrees of freedom for sample variance equal to n - 1. 
C)  it produces a minimal positive solution that is not zero, as long as all scores are not exactly the same value. 
D)  it makes the sample variance an unbiased estimator of the population variance and it produces a minimal positive solution that is not zero, so long as all scores are not exactly the same value. 
A)  it makes the sample variance an unbiased estimator of the population variance. 
B)  it makes the degrees of freedom for sample variance equal to n - 1. 
C)  it produces a minimal positive solution that is not zero, as long as all scores are not exactly the same value. 
D)  it makes the sample variance an unbiased estimator of the population variance and it produces a minimal positive solution that is not zero, so long as all scores are not exactly the same value.

Question 13

All other things being equal (so assuming that the value of SS never changes),as sample size increases,

Accepted Answer

A)  the degrees of freedom for sample variance decrease. 
B)  the value of sample variance decreases. 
C)  the value in the numerator for sample variance increases. 
D)  the value in the denominator for sample variance decreases. 
A)  the degrees of freedom for sample variance decrease. 
B)  the value of sample variance decreases. 
C)  the value in the numerator for sample variance increases. 
D)  the value in the denominator for sample variance decreases.

Question 14

When df are in the denominator,the sample variance is:

Accepted Answer

A)  an unbiased estimator of the population variance. 
B)  associated with n - 1 degrees of freedom. 
C)  computed by dividing SS by df. 
D)  all of these. 
A)  an unbiased estimator of the population variance. 
B)  associated with n - 1 degrees of freedom. 
C)  computed by dividing SS by df. 
D)  all of these.

Question 15

A researcher computes the definitional formula for SS and finds that .If this is a sample of 12 scores,then what would the value of sample variance be using the definitional formula?

Accepted Answer

A)  3.7 
B)  4.0 
C)  44 
D)  not possible to know because the scores are not given 
A)  3.7 
B)  4.0 
C)  44 
D)  not possible to know because the scores are not given

Question 16

A researcher records the time (in seconds)it takes a sample of participants to walk alone through a dark portion of campus.The researcher computes SS = 1,200.Assuming that a sample of 25 participants was observed in this study,what is the standard deviation for these data?

Accepted Answer

A)  48 s 
B)  50 s 
C)  6.9 s 
D)  7.1 s 
A)  48 s 
B)  50 s 
C)  6.9 s 
D)  7.1 s

Question 17

The calculation of sample variance will be larger than the population variance for the following data: 3,5,4,7,3,5,4,8,and 9.

Accepted Answer

A) True 
 B)False

Question 18

A researcher computes the computational formula for SS and finds that and .If this is a sample of 6 scores,then what would SS equal using the computational formula?

Accepted Answer

A)  17.5 
B)  3.5 
C)  232 
D)  not possible to know because the sample mean is not given 
A)  17.5 
B)  3.5 
C)  232 
D)  not possible to know because the sample mean is not given

Question 19

Assuming N $\neq$ n and all data are otherwise the same,how will the value of the sample variance be different from the population variance?

Accepted Answer

A)  The sample variance will always be a smaller value than the population variance. 
B)  The sample variance will always be a larger value than the population variance. 
C)  The sample variance, but not the population variance, can be zero. 
D)  The sample variance, but not the population variance, can be negative. 
A)  The sample variance will always be a smaller value than the population variance. 
B)  The sample variance will always be a larger value than the population variance. 
C)  The sample variance, but not the population variance, can be zero. 
D)  The sample variance, but not the population variance, can be negative.

Question 20

Why is it important to divide by df to compute sample variance?

Accepted Answer

A)  Doing so makes the sample variance an unbiased estimator of the population variance. 
B)  Doing so ensures that the value for sample variance varies between 0 and 1. 
C)  Doing so minimizes the likelihood that the sample variance will be a negative value. 
D)  It is not important; there is no advantage for dividing by df. 
A)  Doing so makes the sample variance an unbiased estimator of the population variance. 
B)  Doing so ensures that the value for sample variance varies between 0 and 1. 
C)  Doing so minimizes the likelihood that the sample variance will be a negative value. 
D)  It is not important; there is no advantage for dividing by df.

The interquartile range and semi-interquartile range are the same measure.

A researcher decides to split scores on an exam into quartiles.She determines that a score of 64 is at the 25th percentile,a score of 74 is at the 50th percentile,and a score of 80 is at the 75th percentile.What is the interquartile range (IQR)for these data?

A researcher selects a sample of 24 participants and has them complete a survey on dating preferences.In this example,what are the degrees of freedom for sample variance and what does this represent?

The population standard deviation is equal to 10 when SS = 100 and n = 10.

Which of the following distributions has the largest variability?

The standard deviation is typically reported in research reports with the mean for a data set.

For a set of data that is normally distributed with 32 ± 4 (M ± SD),we know that at least 68% of the data will fall between scores of 28 and 36.

A researcher records the sound (in decibels)during a series of lessons taught by a substitute teacher at a local elementary school.In his study,he found that the sound was 80 ± 6 (M ± SD)decibels.Assuming the data are normally distributed,which of the following is an appropriate conclusion?

All other things being equal,the value in the numerator is computed the same for sample variance and population variance.

For nonnormal distributions,at least 99.7% of data will fall within three standard deviations of the mean.

Which of the following is an example of a distribution with NO variability?

The advantage of squaring the deviation of each score from the mean and then summing is that

All other things being equal (so assuming that the value of SS never changes),as sample size increases,

When df are in the denominator,the sample variance is:

A researcher computes the definitional formula for SS and finds that .If this is a sample of 12 scores,then what would the value of sample variance be using the definitional formula?

A researcher records the time (in seconds)it takes a sample of participants to walk alone through a dark portion of campus.The researcher computes SS = 1,200.Assuming that a sample of 25 participants was observed in this study,what is the standard deviation for these data?

The calculation of sample variance will be larger than the population variance for the following data: 3,5,4,7,3,5,4,8,and 9.

A researcher computes the computational formula for SS and finds that and .If this is a sample of 6 scores,then what would SS equal using the computational formula?

Assuming N $\neq$ n and all data are otherwise the same,how will the value of the sample variance be different from the population variance?

Why is it important to divide by df to compute sample variance?

Introduction to Statistics

Summarizing Data: Frequency Distributions in Tables and Graphs

Summarizing Data: Central Tendency

Probability

Probability, normal Distributions, and Z Scores

Probability and Sampling Distributions

Hypothesis Testing: Significance,effect Size,and Power

Testing Means: One-Sample and Two-Independent-Sample T Tests

Testing Means: Truehe Related-Samples T Test

Estimation and Confidence Intervals

Analysis of Variance: One-Way Between-Subjects Design

Analysis of Variance: One-Way Within-Subjects Repeated-Measuresdesign

Analysis of Variance: Two-Way Between-Subjects Factorial Design

Correlation

Linear Regression and Multiple Regression

Nonparametric Tests: Chi-Square Tests

Nonparametric Tests: Tests for Ordinal Data

Filters

Exam 4: Summarizing Data: Variability

The interquartile range and semi-interquartile range are the same measure.

A researcher decides to split scores on an exam into quartiles.She determines that a score of 64 is at the 25th percentile,a score of 74 is at the 50th percentile,and a score of 80 is at the 75th percentile.What is the interquartile range (IQR)for these data?

A researcher selects a sample of 24 participants and has them complete a survey on dating preferences.In this example,what are the degrees of freedom for sample variance and what does this represent?

The population standard deviation is equal to 10 when SS = 100 and n = 10.

Which of the following distributions has the largest variability?

The standard deviation is typically reported in research reports with the mean for a data set.

For a set of data that is normally distributed with 32 ± 4 (M ± SD),we know that at least 68% of the data will fall between scores of 28 and 36.

A researcher records the sound (in decibels)during a series of lessons taught by a substitute teacher at a local elementary school.In his study,he found that the sound was 80 ± 6 (M ± SD)decibels.Assuming the data are normally distributed,which of the following is an appropriate conclusion?

All other things being equal,the value in the numerator is computed the same for sample variance and population variance.

For nonnormal distributions,at least 99.7% of data will fall within three standard deviations of the mean.

Which of the following is an example of a distribution with NO variability?

The advantage of squaring the deviation of each score from the mean and then summing is that

All other things being equal (so assuming that the value of SS never changes),as sample size increases,

When df are in the denominator,the sample variance is:

A researcher computes the definitional formula for SS and finds that .If this is a sample of 12 scores,then what would the value of sample variance be using the definitional formula?

A researcher records the time (in seconds)it takes a sample of participants to walk alone through a dark portion of campus.The researcher computes SS = 1,200.Assuming that a sample of 25 participants was observed in this study,what is the standard deviation for these data?

The calculation of sample variance will be larger than the population variance for the following data: 3,5,4,7,3,5,4,8,and 9.

A researcher computes the computational formula for SS and finds that and .If this is a sample of 6 scores,then what would SS equal using the computational formula?

Assuming N ≠\neq= n and all data are otherwise the same,how will the value of the sample variance be different from the population variance?

Why is it important to divide by df to compute sample variance?

Introduction to Statistics

Summarizing Data: Frequency Distributions in Tables and Graphs

Summarizing Data: Central Tendency

Probability

Probability, normal Distributions, and Z Scores

Probability and Sampling Distributions

Hypothesis Testing: Significance,effect Size,and Power

Testing Means: One-Sample and Two-Independent-Sample T Tests

Testing Means: Truehe Related-Samples T Test

Estimation and Confidence Intervals

Analysis of Variance: One-Way Between-Subjects Design

Analysis of Variance: One-Way Within-Subjects Repeated-Measuresdesign

Analysis of Variance: Two-Way Between-Subjects Factorial Design

Correlation

Linear Regression and Multiple Regression

Nonparametric Tests: Chi-Square Tests

Nonparametric Tests: Tests for Ordinal Data

Filters

Assuming N $\neq$ n and all data are otherwise the same,how will the value of the sample variance be different from the population variance?