QUIZ ON  THREATS TO INTERNAL VALIDITY 

 ___History                                          Differences in results due to unreliability, changes in the measuring instruments, or in observers   

___Selection                                       Changes in behavior in response to being a subject or to being in an experiment   

 ___Statistical regression                      Unplanned or extraneous events that occur during the research and affect the results                                                           

 ___Pretesting                                       Occurs when subjects in one group learn about treatments or conditions for different groups 

___Instrumentation                                A result due to respondents’ being identified on the basis of extremely high   or low scores 

___Subject attrition                              Occurs when an effect is due to maturational or other natural changes in the subjects (for example, being older, wiser, stronger, tired)

___Maturation                                      Differences between the subjects in the groups may result in outcomes that are different because of group composition  

 ___Diffusion of treatment                     Occurs when the act of taking a test or responding to a questionnaire affects the subjects

 ___Experimenter effects                      Violation of assumptions or misuse of statistical tests

___Treatment replications                     Occurs because of systematic loss of subjects

 ___Subject effects                              Number of replications of the treatment is different from the number of subjects

___Statistical conclusion                      Deliberate or unintended effects of the researcher on subject responses