In the following studies, the techniques for gathering data are as follows:

• Study A: An analysis of a sample of 31,000 patients from New York hospitals suggests that the poor and the elderly sue for malpractice at one-fifth the rate of wealthier patients.

In this study, the data gathering technique used was sampling. This is also highlighted in the description of the study when it said, "a sample of 31,000 patients." Sampling involves analyzing a group that is representative of a whole. In this case, the study uses 31,000 patients rather than all patients who visited New York hospitals.

• Study B: The effects of wind shear on airplanes during both landing and takeoff were studied by using complex computer programs that mimic actual flight.

In this study, the data gathering technique used was simulation. Rather than directly recording the effects of thousands of flights, the researcher used complex programs to simulate the effects of wind shear on airplanes. This is helpful because not all flights in the real world would experience the required wind shear conditions for the study, and equipping enough real aircraft with the necessary equipment would be extremely expensive.

• Study C: A study of all-league football scores attained through touchdowns and field goals was conducted by the National Football League to determine whether field goals account for more scoring events than touchdowns.

In this study, the data gathering technique used was census. A census uses data from every member of a population or from every situation or circumstance in question. By using the football scores and data from all games played throughout the league, the National Football League conducted a census of the games, scores, touchdowns, and field goals to determine if field goals were responsible for more scoring events than touchdowns.

• Study D: An Australian study included 588 men and women who already had some precancerous skin lesions. Half got skin cream containing sunscreen with a sun protection factor of 17; half got an inactive cream. After seven months, those using the sunscreen with sun protection had fewer precancerous skin lesions.

Finally, this study uses experimentation as its data-gathering technique. An experiment is designed to test a hypothesis. It is likely that the hypothesis was that people would develop fewer precancerous skin lesions if they used sunscreen with a sun protection factor of 17. By only giving half the participants of the experiment the cream with a sun protection factor of 17, while the other half got inactive cream, the researchers could determine if the active cream produced the desired effects of reducing the occurrence of precancerous skin lesions.