Question 1

Another name for difference scores is:
A)change scores
B)dependent scores
C)scores
D)deleted scores

Accepted Answer

Difference scores are also known as change scores because they represent the difference or change between two measurements or scores. The other options (dependent scores, scores, deleted scores) are not accurate or appropriate names for difference scores.

Question 2

For the following question(s): Professor Juarez thinks the students in her statistics class this term are more creative than most students at this university. A previous study found that students at this university had a mean score of 35 on a standard creativity test. Professor Juarez finds that her class scores an average of 40 on this scale, with an estimated population standard deviation of 7. The standard deviation of the distribution of means comes out to 1.63. -What effect size did Professor Juarez find? A)(40 - 35)/7 = .71 B)(40 - 35)/1.63 = 3.07 C)(40 - 35)/7²= 5/49 = .10 D)(40 - 35)/1.63²= 5/2.66 = 1.88

Accepted Answer

The answer of For the following question(s): Professor Juarez thinks...

Question 3

A research strategy in which each person is tested more than once is known as:
A)within-subjects design
B)repeated-measures design
C)before-after design
D)any of the above

Accepted Answer

All the options provided (A, B, C) are different terms or variations used to describe a research strategy where each participant is tested more than once, making D (any of the above) the correct answer.

Question 4

The shape of a t distribution:
A)is typically bimodal
B)is typically rectangular
C)will vary according to the mean of the population you used to estimate sample variance
D)will vary according to the degrees of freedom in the sample you used to estimate population variance

Accepted Answer

The shape of a t distribution will vary according to the degrees of freedom in the sample you used to estimate population variance. As degrees of freedom increase, the t distribution will approach a normal distribution.

Question 5

The t score is your sample's mean minus the __________ divided by the __________.
A)sample size; variance of the distribution of means
B)sample size minus 1; standard deviation of the distribution of means
C)population mean; standard deviation of the distribution of means
D)population median; variance of the distribution of means

Accepted Answer

The t score is calculated by subtracting the population mean from the sample's mean and then dividing by the standard deviation of the distribution of means. This formula is used to determine how many standard deviations the sample mean is from the population mean.

Question 6

You do a t test for dependent means in exactly the same way as a t test for a single sample, except that you use something called:
A)the mean variance
B)variance of the dependent means
C)difference scores
D)independent t scores

Accepted Answer

In a t test for dependent means, we compute the difference between each pair of scores (before and after in the same individual) to get the difference scores. We then calculate the mean of these difference scores and perform a t test on this mean to determine whether the mean difference is significantly different from zero. Therefore, we use difference scores in a t test for dependent means.

Question 7

Difference scores are usually used with:
A)a t test for a single sample
B)a t test for dependent means
C)a t test for independent means
D)all of the above

Accepted Answer

Difference scores, also known as paired scores, are used to compare the means of two related groups, which corresponds to a t test for dependent means. This type of t test is used when the same individuals are measured twice or when each individual in one group is matched with a different individual in the other group. It is not appropriate to use difference scores with a t test for a single sample or a t test for independent means.

Question 8

For the following question(s): Professor Juarez thinks the students in her statistics class this term are more creative than most students at this university. A previous study found that students at this university had a mean score of 35 on a standard creativity test. Professor Juarez finds that her class scores an average of 40 on this scale, with an estimated population standard deviation of 7. The standard deviation of the distribution of means comes out to 1.63. -What is the t score? A)(40 - 35)/7 = .71 B)(40 - 35)/1.63 = 3.07 C)(40 -35)/7²= 5/49 = .10 D)(40 - 35)/1.63²= 5/2.66 = 1.88

Accepted Answer

To calculate the t score, we need to use the formula (sample mean - population mean)/(standard deviation of the distribution of means). Plugging in the values, we get (40 - 35)/(1.63) = 3.07. Therefore, the correct answer is B.

Question 9

In a study with 15 degrees of freedom, what would be your cutoff score for a t distribution using a two-tailed test at the .01 level of significance?
A)2.603
B)1.753
C)2.132
D)2.947

Accepted Answer

For a two-tailed test at the .01 level of significance with 15 degrees of freedom, the critical t-value is approximately 2.947.

Question 10

If Professor Juarez had 30 students in her class, and she wanted to test her hypothesis using the 5% level of significance, what cutoff t score would she use? (You should be able to figure this out without a table because only one answer is in the correct region.)
A)304.11
B)1.699
C)-.113
D)-2.500

Accepted Answer

To find the cutoff t-score at a 5% level of significance with 29 degrees of freedom (30 students -1), we can use a t-table or a calculator. Using a calculator or an online t-distribution calculator, we find that the cutoff t-score is 1.699. Therefore, the best choice is B.

Question 11

The difference between a person's score on one testing and the same person's score on another testing:
A)test score
B)deleted score
C)distance score
D)difference score

Accepted Answer

The term "difference score" refers to the numerical difference between a person's score on one testing and their score on another testing, making choice (D) the best option.

Question 12

Other names for the t test for dependent means include all of the following EXCEPT:
A)paired-sample t test
B)t test for matched samples
C)t test for matched pairs
D)independent-sample t test

Accepted Answer

The t test for dependent means is used to compare the means of two related groups, meaning that the same subjects are tested under two different conditions. It is also known as a paired-sample t test, t test for matched samples, or t test for matched pairs. However, it is NOT called the independent-sample t test, as this test is used to compare the means of two independent groups.

Question 13

Suppose the standard deviation she figures (the square root of the unbiased estimate of the population variance)is .85. What is the effect size?
A)5/.85 = 5.88
B) .85/5 = .17
C)(5 - 4.4)/.85 = .71
D) .85/(5 -4.4)= 1.42

Accepted Answer

The effect size is calculated as the difference between the sample mean and the population mean divided by the standard deviation. Here, it is (5 - 4.4)/.85 = .71.

Question 14

In which situation below would you use a t test for dependent means?
A)To compare the level of honesty (based on an honesty scale)in politicians to the level of honesty in students.
B)To compare the level of reading comprehension of students at the beginning of a speed-reading class to their level of reading comprehension at the end of the class.
C)To find the correlation between liking for coffee and tendency to be a "night person" among a group of students.
D)To compare the scores on a tolerance-of-diversity measure between two sororities.

Accepted Answer

A t test for dependent means, also known as a paired-samples t test, is used to compare the means of two related groups, where each participant is in both groups (such as pre-test and post-test scores of the same group). In option B, we are comparing the reading comprehension scores of students before and after a speed-reading class, which is a situation where a t test for dependent means would be appropriate. In contrast, options A, C, and D do not involve related groups, so a t test for dependent means would not be appropriate.

Question 15

In what important way does a t distribution differ from a normal curve?
A)it has slightly less scores at the extremes
B)it has slightly more scores at the extremes
C)it has an extra hump (i.e., bimodal)
D)it does not differ

Accepted Answer

The t distribution is similar to the normal distribution but has heavier tails, meaning it has slightly more scores at the extremes. This allows it to account for the uncertainty that comes with smaller sample sizes.

Question 16

The estimated population variance is:
A)the sum of squared deviation scores divided by N
B)the sum of squared deviation scores divided by N - 1
C)the sum of squared deviation scores divided by N - standard deviation
D)the sum of squared deviation scores minus 1

Accepted Answer

The estimated population variance is calculated by taking the sum of the squared deviation scores (the difference between each score and the mean, squared) and dividing by the number of scores (N). This formula is represented by choice B.

Question 17

It takes a slightly __________ sample mean to get a significant result when using a t distribution than when using a normal curve.
A)more negative
B)less extreme
C)more extreme
D)more exact

Accepted Answer

This is because the t distribution has thicker tails than the normal curve, which means that it is more spread out and has more variability. As a result, it is less likely to reject the null hypothesis and obtain a significant result unless the sample mean is more extreme than it would need to be with a normal curve.

Question 18

If 15 research participants take a pretest and a posttest with a mean change score of 1.5, and if the standard deviation of the comparison distribution is .5, what is the t score?
A)1.5/(15 - 1)= .11
B)1.5/15 = .10
C)1.5/.5 = 3.00
D)15/1.5 = 10

Accepted Answer

The formula for calculating the t score is (M1 - M2) / (s / sqrt(n)), where M1 is the mean of the posttest scores, M2 is the mean of the pretest scores, s is the standard deviation of the comparison distribution, and n is the number of participants. In this case, M1 - M2 = 1.5, s = 0.5, and n = 15. Therefore, the t score is (1.5) / (0.5 / sqrt(15)) = 3.00.

Question 19

There is an entire family of t distributions that vary in shape according to the degrees of freedom used to estimate the population variance. However, for any particular degrees of freedom, there is/are only _____ t distribution (s).
A)0
B)1
C)2
D)3

Accepted Answer

For any particular degrees of freedom, there is only one t distribution.

Question 20

In a study with 10 degrees of freedom, what would be your cutoff score for a t distribution using a one-tailed test at the .05 level of significance?
A)1.372
B)1.813
C)2.764
D)2.228

Accepted Answer

For a one-tailed t-test at the .05 level of significance with 10 degrees of freedom, the cutoff score is 1.813 according to t distribution tables.

Quiz 8: Introduction to the T Test: Single Sample and Dependent Means

Another name for difference scores is:

A research strategy in which each person is tested more than once is known as:

The shape of a t distribution:

The t score is your sample's mean minus the divided by the .

You do a t test for dependent means in exactly the same way as a t test for a single sample, except that you use something called:

Difference scores are usually used with:

In a study with 15 degrees of freedom, what would be your cutoff score for a t distribution using a two-tailed test at the .01 level of significance?

If Professor Juarez had 30 students in her class, and she wanted to test her hypothesis using the 5% level of significance, what cutoff t score would she use? (You should be able to figure this out without a table because only one answer is in the correct region.)

The difference between a person's score on one testing and the same person's score on another testing:

Other names for the t test for dependent means include all of the following EXCEPT:

Suppose the standard deviation she figures (the square root of the unbiased estimate of the population variance) is .85. What is the effect size?

In which situation below would you use a t test for dependent means?

In what important way does a t distribution differ from a normal curve?

The estimated population variance is:

It takes a slightly __________ sample mean to get a significant result when using a t distribution than when using a normal curve.

If 15 research participants take a pretest and a posttest with a mean change score of 1.5, and if the standard deviation of the comparison distribution is .5, what is the t score?

There is an entire family of t distributions that vary in shape according to the degrees of freedom used to estimate the population variance. However, for any particular degrees of freedom, there is/are only _____ t distribution (s) .

In a study with 10 degrees of freedom, what would be your cutoff score for a t distribution using a one-tailed test at the .05 level of significance?