In writing up a research report, a psychol- ogist concluded by saying, "These results prove my hypothesis. They provide con- clusive evidence that working crossword puzzles improves vocabulary." Without knowing the details of the researcher's procedures, what could you say about each of the following:

a. Assuming that the findings are statisti- cally significant, are the researcher's conclusions justified? Explain.

b. Assume that several researchers have conducted similar experiments. The pre- vious findings have been inconclusive. What can be said about the conclusion in view of prior research?

c. Given your answers to

(a) and (b), reword the experimenter's conclusions appropriately.

d. If you chose to conduct a similar study, what extraneous variables might affect the internal validity of the experiment?

e. Explain how aggregation could be used to broaden the implications of these findings.