Читать книгу Applied Biostatistics for the Health Sciences - Richard J. Rossi - Страница 47

IN THE planning stages of a research project, a set of research questions is developed and refined. Once a well-defined set of research questions has been developed, a target population will be identified so that the goals of the research project can be attained by sampling the target population. The target population is the reference population about which the research questions apply, from which the sample data will be collected, and is the population that statistical inferences will be made about. The research questions will also define the set of variables that must be measured on each unit that is sampled. A variable is a characteristic that will be measured on the units of the target population.

It is important to note that each variable will then have its own population of values. That is, because the units of the population will differ to some degree, a variable will often reflect the differences between the population units and take on several different values. The research questions will also need to be converted into questions about the particular characteristics of the population of values of a variable. In particular, the research questions must be expressed as questions concerning the parameters of the population of values of the variable so that statistical methods can be used to estimate, test, or predict the values of the parameters of interest.

In converting the research questions to questions about the parameters of a population, it is critical for a biomedical researcher and a biostatistician to work together to identify the parameters of the population that are relevant to the research questions being asked. The biomedical research team will also need to determine all of the variables that will be measured before collecting the sample data. In a well-designed research project, it is likely that a biomedical researcher and a biostatistician will work together to design the appropriate sampling plan and to determine the appropriate statistical methodology that will provide meaningful and accurate statistical inferences about the target population and the research questions.