Exam 11: The t Test for Two Related Samples

A repeated-measures study and matched-subjects study both produce t statistics with df = 20.The repeated-measures study used more participants than the matched-subjects study.

Which of the following describes the effect of an increase in the variance of the difference scores in a repeated-measures design?

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.

In a repeated-measures experiment,each individual participates in one treatment condition and then moves on to a second treatment condition.One of the major concerns in this type of study is that participation in the first treatment may influence the participant's score in the second treatment.What is this problem is called?

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

A research report describing the results from a repeated-measures t test states that "t(22)= 1.71, p > .05." From this report,what was the outcome of the hypothesis test?

Which of the following will not increase the width of a confidence interval?

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?

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

Which of the following describes the effect of increasing sample size in a repeated-measures design?

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 MD = 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.

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

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?

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.

In a repeated-measures study comparing two treatments with a sample of n = 15 participants,the researcher measures two scores for each individual to obtain a total of 30 scores and the repeated-measures t statistic has df = 29.

If a repeated-measures study shows a significant difference between two treatments with α = .01,then what can you conclude about measures of effect size?

A repeated-measures study uses a total of n = 10 participants to compare two treatment conditions.How many scores are measured in this study,and how many scores are actually used to compute the sample mean and the sample variance?

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

A researcher obtains t(20)= 2.00 and MD = 9 for a repeated-measures study.If the researcher measures effect size using the percentage of variance accounted for,what value will be obtained for r²?

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.