Question 1

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

Question 2

A reason for squaring deviations to compute SS in the numerator includes which of the following?

Accepted Answer

A) The sum of the differences of scores from their mean is zero. 
B) The sum of the squared differences of scores from their mean is minimal. 
C) Squaring scores can be corrected easily by square rooting. 
D) all of the above

Question 3

A researcher records the following scores on a working memory quiz for two samples.Which sample has the largest standard deviation? Sample A: 2,3,4,5,6,7,and 8
Sample B: 4,5,6,7,8,9,and 10

Accepted Answer

A) Sample A 
B) Sample B 
C) Both samples have the same standard deviation.

Question 4

A researcher computes the definitional formula for SS,as finds that ∑(x-M)= 44.If this is a sample of 12 scores,then what would the value of sample variance be using the computational formula?

Accepted Answer

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

Question 5

Each deviation in the numerator for variance is squared because

Accepted Answer

A) without squaring each deviation,the solution for SS would be zero 
B) this inflates the value for variance,making it more accurate 
C) without squaring each deviation,the solution could be negative 
D) both A and C

Question 6

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: 3,3,3,3,33,and 3 
C) scores: 1,2,3,4,5,and 6 
D) scores: 5,5,5,5,5,and 5

Question 7

A researcher records the following scores for attention during a video game task for two samples.Which sample has the largest standard deviation? Sample A: 10,12,14,16,and 18
Sample B: 20,24,28,32,and 36

Accepted Answer

A) Sample A 
B) Sample B 
C) Both samples have the same standard deviation.

Question 8

All other things being equal,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.

Question 9

The sample variance is computed by dividing SS by ____;whereas the population variance is computed by dividing SS by ____.

Accepted Answer

A) N;df 
B) df;n - 1 
C) df;N 
D) n - 1;df

Question 10

A researcher computes the following scores: 12,8,14,12,and 10.If these scores were substituted into each formula,the sample variance would be smaller than the population variance.

Accepted Answer

A) True 
 B)False

Question 11

How is the sample variance computed differently from the population variance?

Accepted Answer

A) only one formula includes a computation for SS 
B) the calculation in the numerator is different 
C) the calculation in the denominator is different 
D) both B and C

Question 12

Which of the following values is NOT needed to compute sample variance using the computational formula,but is needed to compute the definitional formula?

Accepted Answer

A) sample mean 
B) scores (x) 
C) sample size 
D) degrees of freedom

Question 13

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 the above

Question 14

A measure of the average squared distance of scores from the mean is called the

Accepted Answer

A) range 
B) IQR 
C) variance 
D) sum of squares

Question 15

The 50th percentile is also called the median quartile.

Accepted Answer

A) True 
 B)False

Question 16

A researcher measures the number of trials it takes two samples of participants to master a new task.In both samples,SS = 240.Sample A consisted of 12 participants and Sample B consisted of 18 participants.Which sample is associated with the largest variance?

Accepted Answer

A) Sample A 
B) Sample B 
C) Both samples have the same variance. 
D) There is not enough information to answer this question.

Question 17

One reason the denominator for sample variance is (n - 1)is because this makes it an unbiased estimator of the population variance.

Accepted Answer

A) True 
 B)False

Question 18

When the sample variance is computed as SS divided by n,it will underestimate the population variance on average.

Accepted Answer

A) True 
 B)False

Question 19

Fractiles are ways that data can be divided into two or more equal parts.An example of a fractile includes

Accepted Answer

A) the median 
B) quartiles 
C) percentiles 
D) all of the above

Question 20

Which of the following is the best explanation for why the standard deviation is almost always reported with the mean?

Accepted Answer

A) The standard deviation measures the spread of scores from the mean,so it is important to know both the mean and the standard deviation. 
B) The standard deviation is also a measure of central tendency,so it is important to report this value with the mean. 
C) The mean and standard deviation estimate basically the same thing,so these values are typically reported together. 
D) This is not true;the standard deviation is rarely reported with the mean.

Exam 4: Summarizing Data: Variability

Which of the following distributions has the largest variability?

A reason for squaring deviations to compute SS in the numerator includes which of the following?

A researcher records the following scores on a working memory quiz for two samples.Which sample has the largest standard deviation? Sample A: 2,3,4,5,6,7,and 8 Sample B: 4,5,6,7,8,9,and 10

A researcher computes the definitional formula for SS,as finds that ∑(x-M) = 44.If this is a sample of 12 scores,then what would the value of sample variance be using the computational formula?

Each deviation in the numerator for variance is squared because

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

A researcher records the following scores for attention during a video game task for two samples.Which sample has the largest standard deviation? Sample A: 10,12,14,16,and 18 Sample B: 20,24,28,32,and 36

All other things being equal,how will the value of the sample variance be different from the population variance?

The sample variance is computed by dividing SS by ;whereas the population variance is computed by dividing SS by .

A researcher computes the following scores: 12,8,14,12,and 10.If these scores were substituted into each formula,the sample variance would be smaller than the population variance.

How is the sample variance computed differently from the population variance?

Which of the following values is NOT needed to compute sample variance using the computational formula,but is needed to compute the definitional formula?

The sample variance is:

A measure of the average squared distance of scores from the mean is called the

The 50th percentile is also called the median quartile.

A researcher measures the number of trials it takes two samples of participants to master a new task.In both samples,SS = 240.Sample A consisted of 12 participants and Sample B consisted of 18 participants.Which sample is associated with the largest variance?

One reason the denominator for sample variance is (n - 1)is because this makes it an unbiased estimator of the population variance.

When the sample variance is computed as SS divided by n,it will underestimate the population variance on average.

Fractiles are ways that data can be divided into two or more equal parts.An example of a fractile includes

Which of the following is the best explanation for why the standard deviation is almost always reported with the mean?