What does the process of pre-testing in matched pairs design aim to achieve?

The process of pre-testing in a matched pairs design is primarily focused on matching participants based on a relevant characteristic, which is why this choice is correct. In matched pairs designs, researchers identify pairs of participants who are similar in key ways, such as age, gender, or baseline performance on a relevant measure. This ensures that any differences observed in the outcomes of the experiment can be attributed to the experimental conditions rather than to individual differences between participants.

Successfully implementing pre-testing helps strengthen the validity of the research findings by controlling for these variables, allowing for more accurate comparisons between the experimental groups. Essentially, pre-testing serves as a foundational step in the design process to ensure that the groups are equivalent before any manipulation or treatment occurs, enhancing the reliability of the conclusions drawn from the study.