### The Null Hypothesis, Repeated-Measures T Test & Design – Research Study Quiz

The key terms in these Statistic Research chapters include Repeated-Measures T Test, The Null Hypothesis, Rejecting The Null, Repeated Measures Design & Research Study Quiz

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

**µD = 0**

If the null hypothesis is true, what value is expected on average for the repeated-measures t statistic?

**0**

The null hypothesis for a repeated-measures test states:

**The entire population will have a mean difference of μD = 0.**

A researcher conducts a repeated-measures study to evaluate a treatment with a sample of n = 16 participants and obtains a t statistic of t = 1.94. The treatment expected to increase scores and the sample mean shows an increase. Which of the following is the correct decision for a hypothesis test using α = .05.**Reject the null hypothesis with a one-tailed test but fail to reject with two tails**

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?

**µD = 0**

If the null hypothesis is true, what value is expected on average for the repeated-measures t statistic?

**0**

The null hypothesis for a repeated-measures test states:

**The entire population will have a mean difference of μD = 0.**

A researcher conducts a repeated-measures study to evaluate a treatment with a sample of n = 16 participants and obtains a t statistic of t = 1.94. The treatment expected to increase scores and the sample mean shows an increase. Which of the following is the correct decision for a hypothesis test using α = .05.**Reject the null hypothesis with a one-tailed test but fail to reject with two tails**

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

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

A researcher plans to conduct a research study comparing two treatment conditions with a total of 20 scores in each treatment. Which of the following designs would require only 20 participants?

**A repeated-measures design**

A repeated-measures experiment and a matched-subjects experiment each produce a t statistic with df = 10. How many individuals participated in each study?

**11 for repeated, and 22 for matched**

A repeated-measures study comparing two treatment conditions, a researcher obtains a sample of n = 9 difference scores with a mean of MD = 4 and a variance of s2 = 36. What is the value for the repeated-measures t statistic for these data?

**4/2**

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**

A researcher conducts a repeated-measures study to evaluate a treatment with a sample of n = 16 participants and obtains a t statistic of t = 1.94. The treatment is expected to increase scores and the sample mean shows an increase. Which of the following is the correct decision for a hypothesis test using α = .05.

**Reject the null hypothesis with a one-tailed test but fail to reject with two tails.**

A research report describing the results from a repeated-measures study states: The data show no significant difference between the two treatments, t(10) = 1.65, p > .05. Based on this report, you can conclude that a total of ____ individuals participated in the research study .

**11**

In general, if the variance of the difference scores increases, then what will happen to the value of the t statistic?

**It will decrease (move toward 0 at the center of the distribution).**

Why t statistics variabale than Z scores

**The extra variability caused by variations in the sample variance**

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**

What is indicated by a large variance for a sample of difference scores?

**An inconsistent treatment effect and a low likelihood of a significant difference**

Assuming that other factors are held constant, which of the following would tend to increase the likelihood of rejecting the null hypothesis?

**Increase the sample mean difference.**

If the sample size held constant, which of the following will produce the widest 90% confidence interval for the population mean difference for a repeated-measures study?

**MD = 5 with s2 = 5 for the difference scores**

Which set of characteristics will produce the smallest value for the estimated standard error

**A large sample size and a small sample variance**

If the other factors are held constant, what is the effect of increasing the sample variance

**It will increase the estimated standard error and decrease the likelihood of rejecting Ho**

With Alpha =.05 and df= 8, the critical values for a two-tailed test are t=+-2.306. assuming all other factors are held constant, if the df value were increased to df= 20, what would happen to the critical values for t

**They would decrease (move closer to zero)**

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

**False**

For the following data from a repeated-measures study, the sample mean difference is MD = 4.

Participant X1 X2

A 1 7

B 4 8

C 5 3

**False**

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 general, as the variance of the difference scores increases, the likelihood of finding a significant difference also increases.

**False**

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

**False**

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

**True**

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**

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

**False**

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

**µD = 0**

If the null hypothesis is true, what value is expected on average for the repeated-measures t statistic?

**0**

The null hypothesis for a repeated-measures test states:

**The entire population will have a mean difference of μD = 0.**

A researcher conducts a repeated-measures study to evaluate a treatment with a sample of n = 16 participants and obtains a t statistic of t = 1.94. The treatment is expected to increase scores and the sample mean shows an increase. Which of the following is the correct decision for a hypothesis test using α = .05.**Reject the null hypothesis with a one-tailed test but fail to reject with two tails**

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

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

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.

**True**

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.

**True**