21 4 Points Internal validity often receives little attention in research proposals, perhaps because: it is not very important. there is no agreement as to what it means. there is no way to handle problems of internal validity. a study can be carried out without considering it. Question 22 4 Points Interviews and questionnaires as data-collection methods: are more effective than observational techniques. reveal only information the subject is willing to report. cannot be considered to have validity. provide no information about past behavior. Question 23 4 Points Loss of subjects is a threat to internal validity because: it reduces the size of the sample. those lost may differ on the dependent variable from the remainder. it reduces the power of statistical tests of significance. it means that the results of the study are less generalizable. Question 24 4 Points Researchers can obtain evidence of validity by comparing the performance: on one instrument with performance on some other, independent criterion. on one form of a test and another form of the same test. on the even-numbered items on a test and the odd-numbered items on that test. recorded by two administrations of the same test. Question 25 4 Points The _____ method of estimating reliability involves comparing responses to different sets of items that are part of an instrument. test-retest internal-consistency equivalent-forms scoring observer agreement