For each given purpose statement or research objective in a–d, determine the corresponding research methodology you think is most appropriate, and explain why you think it is appropriate. Note that in some cases, depending on how the study is implemented, more than one research methodology might be appropriate.

a. To investigate the effects of three methods for keeping airport managers up-to-date on TSA security protocols. Airport managers may be assigned at random to the differ- ent methods.

b. To investigate changes in cognitive functioning by testing a sample of GA pilots older than 50 years every 5 years for the next 20 years.

c. To investigate the extent to which an aviation meteorology prognosis test predicts subsequent aviation meteorology achievement of flight students.

d. To investigate the relationship between GA pilots' flight hours and their level of risk perception.