AP PSYCHOLOGY

Detailed explanation-1: -There are eight threats to internal validity: history, maturation, instrumentation, testing, selection bias, regression to the mean, social interaction and attrition.

Detailed explanation-2: -However, the disadvantage of independent measures design is that there is the potential for error due to individual differences between the groups of participants. A repeated measures design consists of testing the same individuals on two or more conditions.

Detailed explanation-3: -Internal validity refers specifically to whether an experimental treatment/condition makes a difference or not, and whether there is sufficient evidence to support the claim.

Detailed explanation-4: -Selection bias: Also considered a threat to internal validity, selection bias describes differences between groups in a study that may relate to the independent variable-like motivation or willingness to take part in the study, or specific demographics of individuals being more likely to take part in an online survey3.