Question

Participants in a research study are given a list of words to study for 3 minutes and then, following a delay, are asked to recall the list. The length of the delay is manipulated between participants to be either 2 minutes, 5 minutes, or 10 minutes. Since different groups need different amounts of time, the first 25 participants who arrive are assigned to the 10-minute group, the next 25 are assigned to the 5-minute group, and the final 25 are assigned to the 2-minute group. What confound does this create?

Answer 1

Answer:

Selection effect

Explanation:

The participants, who arrived early may be systematically different from the later arrived participants, so the differences between the group performances may result due to this instead of the independent variable.

Selection effect, also referred to as the selection bias. This is the bias created by the selection of data for analysis, individuals, or groups in a way that affects proper randomization, hence the sample obtained is not typical of the population which is intended to be analyzed.