HEALTH SERVICES RESEARCH METHODS
Selecting a Relevant Sample / Evaluating a Sample | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Paper details
Assignment Details — Course: Research Topics in Health Administration Assignment Readings – • Use the following Web resource: Assignment case instructions — Discussion Question 2: Evaluating a Sample — Welcome to Week 4! A new healthcare manager at a hospital notices that the emergency room (ER) of the hospital is frequently used for nonemergency treatment. This is an inappropriate use of valuable resources from the hospital’s and the insurer’s point of view. For the patient, too, an ER visit, costing about $400, is much more expensive than a visit to a family physician. Clearly, the patients should be discouraged from visiting the ER for nonemergency treatment. What would be the best way to achieve this goal? Would patient education make a difference? The manager commissions a study to estimate the impact of patient education on use of ER for nonemergency treatment. How large should the sample be? A general standard is that in an experimental design, we should have at least 25 subjects per condition. We have two conditions: participation and nonparticipation in the patient education program. We need at least (25 x 2 =) 50 subjects. However, some people contacted may decline to participate in an information program. Typically less than half of the people contacted agree to participate. Therefore, the researcher needs to contact at least 50 subjects per condition. So the sample size is at least (50 x 2 =) 100. What type of subjects should be included in the sample? Researchers study a sample because it is not practical to study the whole population. But the aim is to reach a conclusion that applies to the population. The sample, then, should represent the population so that what is true of the sample may be assumed to be true of the population. Sample Characteristics When subjects for a study are selected, researchers only need to take into account the characteristics of interest to the study. In the example of the ER, factors such as age, income level, education, insurance, and health status are relevant. Suppose that in the area the hospital serves, 5% of the population has high incomes and 10% of the population is over 65 years of age. If the sample has similar proportions of subjects with these and other relevant characteristics, it is a representative sample. Height, weight, color of eyes, state of origin, and hundreds of other such characteristics are not relevant to the study and need not be considered. Research Topic and Sampling So far, we have spoken of samples of people. The subject of research may, however, relate to any objects, for example, organizations, health systems, or health promotion programs. The research question and the study design determine the subjects of the sample and how they are selected. Take as an example the Waxman Report we introduced in Week 2. The study was commissioned by a policy maker in order to evaluate the scientific accuracy of the content of these educational programs. The sample in this study is not people but 13 of the most popular abstinence-only curricula. The incidence of obesity has reached epidemic proportions in the U.S. One of the causes of obesity is physical inactivity. Technological advances make much household work and other labor unnecessary. Physical activity would now come mainly from sport and other recreational activities. Are there sufficient opportunities for recreational activities? If there are, can we expect that people use them? Further, can we expect a reduction in the incidence of obesity? |
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