Les Leventhal

Section Selection in Multi-Section Courses: Implications for the Validation and Use of Teacher Rating Forms.

Researchers know little about determiners of section selection in multi-section college courses. Studies on teacher evaluation and on the validity of teacher rating forms have often assumed section to section equivalence of students assigned by customary registration procedures. To investigate the section selection process, a questionnaire containing items on personal history, reasons for section selection, and sources of information about the instructor was administered to 1,188 undergraduate students in multi-section first year and advanced psychology courses. Major findings were: (1) students significantly differed across sections on biographical variables and on section selection reasons, (2) time at which class was scheduled (classtime) and teachers reputation were the primary reasons for section choice, (3) teachers reputation was less important than classtime for first year students, but comparable to classtime for advanced students, and (4) reports from other students and published ratings were, respectively, the first and second most frequent source of instructor reputation information.

ANSWERING TWO CRITICISMS OF HYPOTHESIS TESTING

Two generations of methodologists have criticized hypothesis testing by claiming that most point null hypotheses are false and that hypothesis tests do not provide the probability that the null hypothesis is true. These criticisms are answered. (1) The point-null criticism, if correct, undermines only the traditional two-tailed test, not the one-tailed test or the little-known directional two-tailed test. The directional two-tailed test is the only hypothesis test that, properly used, provides for deciding the direction of a parameter, that is, deciding whether a parameter is positive or negative or whether it falls above or below some interesting nonzero value. The point-null criticism becomes unimportant if we replace traditional one- and two-tailed tests with the directional two-tailed test, a replacement already recommended for most purposes by previous writers. (2) If one interprets probability as a relative frequency, as most textbooks do, then the concept of probability cannot meaningfully be attached to the truth of an hypothesis; hence, it is meaningless to ask for the probability that the null is true. (3) Hypothesis tests provide the next best thing, namely, a relative frequency probability that the decision about the statistical hypotheses is correct. Two arguments are offered.

UPDATING THE DEBATE ON ONE- VERSUS TWO-TAILED TESTS WITH THE DIRECTIONAL TWO-TAILED TEST

For half a century, methodologists have debated when to use one-and two-tailed tests. But they conducted the debate with scarcely a mention of the little known directional two-tailed test—the only hypothesis test that, properly used, provides for a decision in either direction. In contrast, the traditional two-tailed test assesses nondirectional statistical hypotheses and does not provide for a directional decision. A directional two-tailed test with unequal rejection regions can have virtually the same power as a one-tailed test and, unlike one-tailed tests, it provides for deciding in the unpredicted direction. However, a problem unresolved for one-tailed tests remains for the directional two-tailed test, namely, whether one should create unequal rejection regions just because one has grounds to predict an outcomes direction. Nevertheless, the directional two-tailed test will satisfy research needs much more frequently than will traditional tests and should be adopted as the primary, general-purpose hypothesis test.

ANSWERING TWO CRITICISMS OF HYPOTHESIS TESTING: REPLY TO SERLIN '

Two criticisms of hypothesis testing have been repeated for half a century. Leventhal (1999) defended against those criticisms. Serlin (2000) commented on Leventhals paper and criticized parts of Leventhals defense. Serlins comments are discussed and his criticisms answered.