## Repeated-Measures Study, Rejecting The Null Hypothesis

The key terms in these Statistic chapters include Repeated-Measures Study, Repeated Measures T Test, Sample Mean, Rejecting The Null, Repeated-Measures T Statistic, Rejecting The Null Hypothesis, Independent-Measures Study, Sample, Variance, Research Design, Correlation, Research Study.

A repeated-measures study and an independent-measures study both produce a t statistic with df = 20. The repeated-measures study used more subjects than the independent-measures study.

**False**

For a repeated-measures study, if the null hypothesis is true, then what value should be obtained for the sample mean.

**MD near 0**

In general, what characteristics of the difference scores are most likely to produce a significant t statistic for the repeated-measures hypothesis test?

**A large number of scores and a small variance**

For a repeated-measures study, a small variance for the difference scores indicates that the treatment has little or no effect.

**False**

For a repeated-measures study, if the null hypothesis is true, then what value should be obtained for the sample mean.

**MD near 0**

For the following data from a repeated-measures study, the sample mean difference is MD = 1Participant X1 X2

A 1 5

B 4 6

C 5 2

**True**

A repeated-measures study and an independent-measures study both produce a t statistic with df = 20. The repeated-measures study used more subjects than the independent-measures study.

**False**

In a repeated measures study, the null hypothesis says that the mean for the sample of difference scores is equal to zero.

**False**

A researcher would like to compare two treatment conditions with a set of 30 scores in each treatment. If a repeated-measures design is used, the study will require n = 60 participants.

**False**

The estimated standard error in the denominator of the repeated-measures t statistic measures the average mean difference that is expected for a sample selected from a population with a zero mean difference.

**True**

For which of the following situations would a repeated-measures research design be appropriate?

**Comparing pain tolerance with and without acupuncture needles**

Which of the following is the correct null hypothesis for a repeated-measures t test?

**mD = 0**

In general, what characteristics of the difference scores are most likely to produce a significant t statistic for the repeated-measures hypothesis test?

**A large number of scores and a small variance**

Although a repeated-measures study measures two scores for each participant, the sample mean and variance are computed using only one score for each participant.

**True**

A researcher reports df = 18 for a repeated-measures t statistic. This research study used a total of n = 19 participants.

**True**

For a repeated-measures study, as the variance of the difference scores increases, the likelihood of finding a significant difference also increases.

**False**

A repeated-measures research study comparing two treatments with a set of 10 scores in each treatment will produce a t statistic with df = 18.

**False**

In general, what is the effect of an increase in the variance for the sample of difference scores?

**An increase in the standard error and a decrease in the value of t**

A research report describing the results from a repeated-measures study states that the data show no significant difference between the two treatments, t(10) = 1.65, p > .05. Based on this report, how many individuals participated in the research study?

**11**

A repeated-measures study using a sample of n = 20 participants would produce a t statistic with df = ____.

**19**

A repeated-measures study comparing two treatments with a sample of n = 4 participants produces MD = 3 with SS = 48 for the set of difference scores. What is the repeated-measures t statistic for these data?

**3/2 = 1.50**

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.

**True**

For a repeated-measures study comparing two treatment conditions, a researcher obtains Cohen’s d = 0.50 for a sample of n = 4 scores with a variance of s2 = 16. What is the value of the sample mean?

**MD = 2**

Which of the following describes the effect of increasing sample size?

**There is little or no effect on measures of effect size, but the likelihood of rejecting the null hypothesis increases.**

Delores must grade a driver’s test completed by a group of training students. She knows that driver’s test scores are normally distributed with µ = 50 and σ = 6. Students are required to score in the top 75% of students on the test in order to pass the test and continue on with the training course. Which score do students need to obtain at a minimum in order to pass the test and continue with the course?

**X = 46**

A highly selective university requires that applying students complete an entrance exam with µ = 60 and σ = 16. Applying students must avoid scoring in the bottom 89.5% of scores on the exam in order to be accepted into the university. Applicants must score more than _____ in order to be accepted to the university.

**X = 80**

A set of X and Y scores has M X = 4, SS X = 10, M Y = 5, SS Y = 40, and SP = 20. Which is the regression equation for predicting Y from X?

**Ŷ = 2X – 3**

A set of n = 15 pairs of scores ( X and Y values) produces a correlation of r = 0.40. If each of the X values are multiplied by 2 and the correlation is computed for the new scores, which value will be obtained for the new correlation?

**r = 0.40**

Which correlation should be used to measure the relationship between gender and grade point average for a group of college students?

**point-biserial correlation (used when one variable is dichotomous)**

A researcher assesses self-esteem among college students at the beginning of the semester using a self-report questionnaire, as well as three months later at the end of the semester among the same sample of college students using the exact same self-report measure of self-esteem. The researcher determines that there is a significant positive relationship between self-esteem measured at the beginning and end of the college semester for the students sampled. This demonstrates how correlations can be used to demonstrate _____.

**Reliability**

As the sample size gets larger, the size of the correlation needed for significance _____

**Gets smaller**

For the following data from a repeated-measures study, the sample mean difference is MD = 1Participant X1 X2

A 1 5

B 4 6

C 5 2

**True**

For a repeated-measures study, a small variance for the difference scores indicates that the treatment has little or no effect.

**False**

In a repeated measures study, the null hypothesis says that the mean for the sample of difference scores is equal to zero.

**False**

For which of the following situations would a repeated-measures research design be appropriate?

**Comparing pain tolerance with and without acupuncture needles**

Which of the following is the correct null hypothesis for a repeated-measures t test?

**mD = 0**

A researcher reports df = 18 for a repeated-measures t statistic. This research study used a total of n = 19 participants.

**True**

For a repeated-measures study, as the variance of the difference scores increases, the likelihood of finding a significant difference also increases.

**False**

A research report describing the results from a repeated-measures study states that the data show no significant difference between the two treatments, t(10) = 1.65, p > .05. Based on this report, how many individuals participated in the research study?

**11**

A repeated-measures study using a sample of n = 20 participants would produce a t statistic with df = ____.

**19**

A repeated-measures study comparing two treatments with a sample of n = 4 participants produces MD = 3 with SS = 48 for the set of difference scores. What is the repeated-measures t statistic for these data?

**3/2 = 1.50**

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.

**True**