Statistics for the Behavorial Sciences 9th Edition Chap. 11

Question Answer
The dependent variable is measure two or more times for each individual in a single sample. The same group of subjects is used in all of the treatment conditions. Repeated-Measures Design or Within-Subject Design
Each individual in one sample is matched with an individual in the other sample. The matching is done so that the two individuals are equivalent with respect to a specific variable the researcher would like to control. Matched-subjects design
For a research study comparing two treatment conditions, what characteristic differentiates a repeated-measures t statistic? For a repeated-measures design, the same group of individuals is tested in both of the treatments. An independent-measures design uses a separate group for each treatment.
Describe the data used to compute the sample mean and the sample variance for the repeated-measures t statistic. The two scores obtained for each individual are use to compute a difference score. The sample of difference scores is used to compute the mean and variance.
In words and symbols, what is the null hypothesis for a repeated measures t test? H0: uD = 0
The null hypothesis states that, for the general population, the average difference between two conditions is zero.
What assumptions must be satisfied for repeated-measures t tests to be valid? The observations within a treatment are independent. The population distribution of D scores is assumed to be normal.
Describe some situations for which a repeated-measures design is well suited. When a particular type of subject is not readily available for a study. When fewer subjects are needed. Studies where time is a factor.
How is a matched-subjects design similar to a repeated-measure design? How do they differ? They are similar in that the role of individual differences in the experiment is reduced. They differ in that there are two samples in a matched-subjects design and only one in a repeated-measure study.
The data from a research study consist of 10 scores in each of two different treatment conditions. How many individual subjects would be needed to produce the data:
a. for an independent-measures design?
20 subjects
The data from a research study consist of 10 scores in each of two different treatment conditions. How many individual subjects would be needed to produce the data:
b. for a repeated-measures design?
10 subjects
The data from a research study consist of 10 scores in each of two different treatment conditions. How many individual subjects would be needed to produce the data:
c. for a matched-subjects design?
20 subjects
The difference between the first and second measurements for each subject in a repeated-measures t test. D scores
D =X2-X1