SUBJECTS AND SAMPLING
age, gender, socioeconomic status, ability, and grade level,
should be indicated, as well as any unique characteristics, for example,
gifted students, students enrolled in a psychology class, or volunteers,
population should be clearly defied. It is especially impor-
tant to provide a specific definition of the population in studies using probability sampling. Vague descriptions, such as “retired workers” or “high-ability students,” should be avoided. The characteristics of each stratum in a stratified sampling procedure should also be included.
of sampling should be dearly described. The spe-
cific type of sampling procedure, such as simple random, stratified, ter, or convenience, should be explicitly indicated in sufficient detail to
enable other researchers to replicate the study.
4. The return rate should be indicated and analyzed. In studies that survey a population, the return rate of questionnaires should be in- dicated. If the return rate is less than 60 percent, the researcher should analyze the implications of excluding a significant portion of the popu- lation. This step is accomplished by comparing the nonrespondents to those who returned the questionnaires to determine if there are signifi- cant differences between the groups.
5. The selection of subjects should be free of bias. The procedures and criteria for selecting subjects should not result in systematic error. Bias is more likely when a researcher is “proving” something to be true, with convenience samples, and when volunteers are used as subjects.
6. Selection procedures should be appropriate for the problem be investigated. If the problem is to investigate science attitudes of mid- dle school students, it would be inappropriate to use high school
as subjects. If the problem is to study the characteristics of effective teaching, the work of student teachers would probably not be very representative of effective teaching behaviors.
7. There should be an adequate number of subjects. If the sample is selected from a population, the sample size must be large enough to represent the population accurately. There must also be a number of subjects in each subgroup that is analyzed. Studies with small samples that report no differences or no relationships should be viewed with caution since a higher number or a better selection of subjects may result in meaningful differences or relationships. Studies that have a
very large number of subjects may report lationships that are of little practical utility.
differences or re-
8. Qualitative studies should have informative and knowledgeable subjects. Since the purpose of qualitative research is to understand a
phenomenon in depth, it is important to select
that will provide
the richest information. The researcher should indicate the criteria used to select the reasons why these particular individuals were selected, and the strategies used for selecting subjects during the study.