Retrospective and Prospective Investigations

Longitudinal investigations designed to determine the risk factors associated with a particular disease are frequently conducted by medical researchers. These epidemiological studies may be either prospective or retrospective. Prospective studies follow up individuals who are initially free of the disease over a period of time to determine what characteristics and behaviors differentiate between people who eventually develop the disease from people who remain free of it. In contrast to prospective studies, which involve looking forward in time, retrospective studies look backward in that they examine the life histories of people who currently have the disease (index cases) to identify correlates and causes of it. These index cases may also be compared on selected variables with people who are currently free of the disease. Like the longitudinal, cross-sectional, and other developmental research designs described earlier, prospective and retrospective studies may

The Past Recaptured

Forgive me, dear reader, for reminiscing occasionally in this book. It is not that my own life has been more extraordinary than the lives of others, though it has been intriguing and always challenging. Rather, I do not believe in letting "the dead past bury its dead," because I agree with the historian that one who does not study the past and learn from it is doomed to repeat it. Reflecting on the events and decisions that played a role in making me what and where I am today has certainly helped me to cope with the present and plan more effectively for whatever tomorrows I may yet enjoy. Furthermore, I hope that my "life review" will inspire you, "Dear Reader," to get in touch with yourself by engaging in a similar process.

With today's emphasis on the "here and now," introspection is not as fashionable as it was BTV (before television). Objective observation and experimentation have become the sine qua non of science and even self-understanding. But the personal past is no longer with us in an objective sense, only memories of it and a few reminders in the form of a familiar face or place. To understand why certain things occurred and how they shaped the persons whom we are requires a trip down memory lane and an effort to recall as clearly as possible what happened then and the circumstances surrounding it.

According to what I somewhat crudely call the "garbage pail" nature of memory, the mind is not particularly selective in what is remembered: It does not recall just a single event or person, but a hodgepodge of things that were there when the event occurred or the person was present. Thus, when I remember the first time I dated a particular girl, I also remember what she was wearing, the movie we saw, and the old car I drove. So now, the memory of her face can be triggered by seeing that same movie on television or a similar car. The writer Marcel Proust knew this, but he was be conducted to determine changes and stability in physical and psychological characteristics over time. It should be emphasized, however, that all of these designs yield only descriptive and correlational results, not causal explanations. The results can be interpreted as one chooses, and they may provide ideas for the generation of interesting causal hypotheses. However, it still requires an experiment, and usually a series of experiments, to produce data interpretable in causal terms.

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