Question 1

Individual differences are characteristics such as age,IQ,gender,and personality that vary from one individual to another.

Accepted Answer

Individual differences refer to variations in characteristics such as age, IQ, gender, and personality that are unique to each individual. Therefore, the statement is true.

Question 2

A set of n = 16 difference scores has a mean of M_D = 4 and a variance of s² = 36.Cohen's d for this sample is d = 4/6.

Accepted Answer

Cohen's d is calculated as the mean difference (in this case, 4) divided by the standard deviation. The standard deviation is the square root of the variance, which is the square root of 36, resulting in 6. Therefore, Cohen's d = 4/6.

Question 3

A repeated-measures research study uses a total of 20 participants to compare two treatment conditions.If the results are used to construct a 90% confidence interval for the population mean difference,then the t values will be ±1.729.

Accepted Answer

The critical t value for a 90% confidence interval with 19 degrees of freedom (20 participants - 1) is ±1.729, so the statement is true.

Question 4

A repeated-measures test usually is more likely to detect a real treatment effect than an independent-measures test because the repeated-measures design typically has a smaller variance and a smaller estimated standard error.

Accepted Answer

The repeated-measures design reduces the variability by controlling for individual differences, making it more likely to detect a treatment effect. As a result, the estimated standard error is smaller, increasing the power of the test.

Question 5

For a repeated-measures study,a small variance for the difference scores indicates that the treatment effect is consistent across participants.

Accepted Answer

A small variance for the difference scores indicates that the difference between the scores of the same participants in two different conditions is consistent, which suggests a consistent treatment effect across participants. Therefore, the correct answer is A.

Question 6

Calculate the difference scores and find M_D for the following data from a repeated-measures study.Subject Treatment 1 Treatment 2 $$\begin{array} { r r r } \mathrm { A } & 12 & 14 \ \mathrm {~B} & 7 & 15 \ \mathrm { C } & 10 & 8 \ \mathrm { D } & 8 & 12 \end{array}$$

Accepted Answer

The answer of Calculate the difference scores and find M_D...

Question 7

Briefly explain the advantages and disadvantages of using a repeated-measures design as opposed to an independent-measures design.

Accepted Answer

The answer of Briefly explain the advantages and disadvantages of...

Question 8

A repeated-measures study with a sample of n = 16 participants produces a repeated-measures t = 2.00.If effect size is measured using r²,then r² = 4/20.

Accepted Answer

The given effect size measure r² is not a valid statistical measure. Therefore, the statement cannot be evaluated as true or false.

Question 9

Repeated-measures designs are particularly well-suited to research studies examining learning or other changes that occur over time.

Accepted Answer

Repeated-measures designs involve measuring the same variables multiple times over a period of time, which makes them ideal for studying changes or learning that occur over time.

Question 10

One advantage of a repeated-measures design is that it typically requires fewer participants than an independent-measures design.

Accepted Answer

A repeated-measures design involves each participant being tested in multiple conditions or at multiple time points, which reduces the need for a large number of participants compared to an independent-measures design where each participant is only tested in one condition.

Question 11

Repeated-measures designs are particularly well-suited to research questions concerning the difference between two distinct populations (for example,males versus females).​

Accepted Answer

Repeated-measures designs are better suited for investigating changes within a single group over time or comparing individuals' performance on multiple task conditions. They are not typically used for comparing two distinct populations as a between-subjects design would be more appropriate.

Question 12

A researcher would like to examine how the chemical tryptophan,contained in foods such as turkey,can affect mental alertness.A sample of n = 9 college students is obtained and each student's performance on a familiar video game is measured before and after eating a traditional Thanksgiving dinner including roast turkey.The average score dropped by M = 14 points after the meal with SS = 1152 for the difference scores.
a. Is there is significant difference in performance before eating versus after eating? Use a two-tailed test with α = .05.
b. Compute r2 to measure the size of the effect.
c. Write a sentence demonstrating how the outcome of the test and the measure of effect size would appear in a research report.

Accepted Answer

The answer of A researcher would like to examine how...

Question 13

One of the major advantages of a repeated-measures design is that it removes individual differences from the variance and,therefore,reduces the standard error.The following two sets of data demonstrate this fact.The first set of data represents the original results from a repeated-measures study.To create the second set of data we started with the original scores but increased the individual differences by adding 10 points to each score for subject B,adding 20 points to each score for subject C,and adding 30 points to each score for subject D.Note that this change produces a huge increase in the differences from one subject to another and a huge increase in the variability of the scores within each treatment condition.​​  ​ 
a. Find the difference scores for each set of data and compute the mean and variance for each sample of difference scores.
b. You should find that both sets of data produce the same mean difference and the same variance for the difference scores. Explain what happened to the huge individual differences that were added to the second set of data.

Accepted Answer

The answer of One of the major advantages of a...

Question 14

A teacher gives a third grade class of n = 16 a reading skills test at the beginning of the school year.To evaluate the changes that occur during the year,students are tested again at the end of the year.Their test scores revealed an average improvement of MD = 4.7 points.
a. If the variance for the difference scores is s2 = 144, are the results sufficient to conclude that there is significant improvement? Use a one-tailed test with α = .05.
b. If the variance for the difference scores is reduced to s2 = 64, are the results sufficient to conclude that there is significant improvement? Use a one-tailed test with α = .05.
c. Describe the effect on reducing the variance of the difference scores.

Accepted Answer

The answer of A teacher gives a third grade class...

Question 15

A researcher would like to determine if relaxation training will affect the number of headaches for chronic headache sufferers.For a week prior to training,each participant records the number of headaches suffered.Participants then receive relaxation training and for the week following training the number of headaches is again measured.The data are as follows: $$\begin{array} { l l } 
\text { Before } & \text { After } \
6 & 4 \
5 & 1 \
3 & 3 \
3 & 1 \
6 & 2 \
2 & 1 \
4 & 3 \
4 & 2 \
\hline
\end{array}$$ 
a. Compute the mean and variance for the sample of difference scores.
b. Do the results indicate a significant difference? Use a two-tailed test with α = .05.
c. Compute Cohen's d to measure the size of the effect.

Accepted Answer

The answer of A researcher would like to determine if...

Question 16

For a repeated-measures design,the sample mean difference is always located exactly in the center of the confidence interval estimate for the population mean difference.

Accepted Answer

This is true. In a repeated-measures design, each subject is measured twice, which means that the sample mean difference is based on the within-subject differences. As a result, the confidence interval for the population mean difference will be centered around the sample mean difference.

Quiz 11: The T Test for Two Related Samples

Individual differences are characteristics such as age,IQ,gender,and personality that vary from one individual to another.

A set of n = 16 difference scores has a mean of M_D = 4 and a variance of s² = 36.Cohen's d for this sample is d = 4/6.

A repeated-measures research study uses a total of 20 participants to compare two treatment conditions.If the results are used to construct a 90% confidence interval for the population mean difference,then the t values will be ±1.729.

A repeated-measures test usually is more likely to detect a real treatment effect than an independent-measures test because the repeated-measures design typically has a smaller variance and a smaller estimated standard error.

For a repeated-measures study,a small variance for the difference scores indicates that the treatment effect is consistent across participants.

Calculate the difference scores and find M_D for the following data from a repeated-measures study.Subject Treatment 1 Treatment 2 $\begin{array} { r r r } \mathrm { A } & 12 & 14 \\\mathrm {~B} & 7 & 15 \\\mathrm { C } & 10 & 8 \\\mathrm { D } & 8 & 12\end{array}$

Briefly explain the advantages and disadvantages of using a repeated-measures design as opposed to an independent-measures design.

A repeated-measures study with a sample of n = 16 participants produces a repeated-measures t = 2.00.If effect size is measured using r²,then r² = 4/20.

Repeated-measures designs are particularly well-suited to research studies examining learning or other changes that occur over time.

One advantage of a repeated-measures design is that it typically requires fewer participants than an independent-measures design.

Repeated-measures designs are particularly well-suited to research questions concerning the difference between two distinct populations (for example,males versus females).

For a repeated-measures design,the sample mean difference is always located exactly in the center of the confidence interval estimate for the population mean difference.

Quiz 11: The T Test for Two Related Samples

Individual differences are characteristics such as age,IQ,gender,and personality that vary from one individual to another.

A set of n = 16 difference scores has a mean of MD = 4 and a variance of s2 = 36.Cohen's d for this sample is d = 4/6.

A repeated-measures research study uses a total of 20 participants to compare two treatment conditions.If the results are used to construct a 90% confidence interval for the population mean difference,then the t values will be ±1.729.

A repeated-measures test usually is more likely to detect a real treatment effect than an independent-measures test because the repeated-measures design typically has a smaller variance and a smaller estimated standard error.

For a repeated-measures study,a small variance for the difference scores indicates that the treatment effect is consistent across participants.

Briefly explain the advantages and disadvantages of using a repeated-measures design as opposed to an independent-measures design.

A repeated-measures study with a sample of n = 16 participants produces a repeated-measures t = 2.00.If effect size is measured using r2,then r2 = 4/20.

Repeated-measures designs are particularly well-suited to research studies examining learning or other changes that occur over time.

One advantage of a repeated-measures design is that it typically requires fewer participants than an independent-measures design.

Repeated-measures designs are particularly well-suited to research questions concerning the difference between two distinct populations (for example,males versus females).​

For a repeated-measures design,the sample mean difference is always located exactly in the center of the confidence interval estimate for the population mean difference.

A set of n = 16 difference scores has a mean of M_D = 4 and a variance of s² = 36.Cohen's d for this sample is d = 4/6.

A repeated-measures study with a sample of n = 16 participants produces a repeated-measures t = 2.00.If effect size is measured using r²,then r² = 4/20.

Repeated-measures designs are particularly well-suited to research questions concerning the difference between two distinct populations (for example,males versus females).