chapter 10

related sample

a group or sample in which the participants are related. Participants can be related in one of two ways: They are observed in more than one group (a repeatedmeasures design), or they are matched, experimentally or naturally, based on common characteristics or traits (a matched-pairs design); also called a dependent sample.

matched-pairs design

a research design in which pairs of participants are selected and then matched, either experimentally or naturally, based on common characteristics or traits; also called a matched-samples design or a matched-subjects design.

repeated-measures design

a research design in which the same participants are observed in each group or treatment. Two types of repeated-measures designs are called the pre-post design and the within-subjects design.

difference score

a score or value obtained by subtracting one score from another.

within-subjects design

a type of repeated-measures design in which researchers observe the same participants across many treatments but not necessarily before and after a treatment

pre-post design

a type of repeatedmeasures design in which researchers measure a dependent variable for participants before (pre) and after (post) a treatment.

estimated standard error for difference scores (sMD)

an estimate of the standard deviation of a sampling distribution of mean difference scores. It is an estimate of the standard error or standard distance that the mean difference scores deviate from the mean difference score stated in a null hypothesis.

related samples test

an inferential statistic used to test hypotheses concerning two related samples selected from populations in which the variance in one or both populations is unknown

error

any unexplained difference that cannot be attributed to, or caused by, having different treatments. The standard error of the mean is used to measure the error or unexplained differences in a statistical design.