# The Null Hypothesis & Repeated-Measures T Test – Quiz

### 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

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