Final answer:
An independent-groups pretest/posttest design example is a study comparing the effects of a new math textbook on students' performance, with students given a pretest and a posttest and randomly assigned to either the experimental or control group. The groups are independent because they are not matched and do not influence each other's outcomes.
Step-by-step explanation:
Example of an Independent-Groups Pretest/Posttest Design
An example of an independent-groups pretest/posttest design would be a study investigating the effectiveness of a new math textbook for high school students. In this scenario, students are given a pretest at the beginning of the semester to assess their math skills prior to using the textbook. Following a year's instruction with the new textbook, a posttest is administered to measure any improvements in their skills. The groups in this study are considered independent, as the participants are only in one group (either the experimental or the control group) and the two groups are not matched based on any criteria. Instead, they are often randomly assigned to control or experimental conditions.
Independence in this context means that the outcomes of one group are not influenced by the outcomes of the other group. This would contrast with a matched-groups design, where participants are paired or grouped based on similarities before the experimental manipulation, such as age, previous math skills, or any other relevant characteristic.
Therefore, in the context of the textbook example, if the students were randomly assigned to either use the new textbook or continue with the standard textbook and were not grouped by any pre-existing similarities, then the groups are independent.