Final answer:
The independent variable in a comparative workbook study would be workbooks. Whether groups are independent or matched in a study about a math textbook's effectiveness depends on whether the same students' pretest and posttest are compared or different groups are used. The dependent variable is the outcome measured by the researcher.
Step-by-step explanation:
In a study designed to assess the comparative effectiveness of two workbooks used in teaching students about laboratory procedures, the independent variable of the study would be option a) Workbooks. An independent variable is the factor that is changed or controlled in a scientific experiment to test the effects on the dependent variable. In the case of testing a new math textbook for high school students, whether the groups are independent or matched depends on the study design. If each student serves as their own control by comparing pretest scores with posttest scores after using the textbook, the groups would be matched because the same students are used before and after. However, if one set of students uses the textbook and another set does not, and their performance is compared, the groups are considered independent.
To clarify, the dependent variable is what the researcher measures to see the effect of the independent variable. For instance, if the effectiveness of teaching methods is being investigated, the dependent variable might be test scores or learning outcomes. The independent variable could be the type of teaching method used.