The purpose of this paper is to present a discussion of developmental/social science research methods using examples of actual studies conducted in the field. These specific methods that the paper discusses are those of: qualitative research; quantitative research; the benefits and drawbacks of combining qualitative and quantitative methods in a single study; hypothesis testing; the power of an experiment; and validity and reliability issues.
According to Barlow and Hersen (1984), qualitative research consists of studies in which the description of observations is not primarily expressed in quantitative (numerical terms). This does not mean that these studies never use numerical measures but only that other methods of description are emphasized.
Qualitative research is often termed "non-experimental" because of its lack of emphasis upon the numerical collection and analysis of data. Best (1981) states that commonly, qualitative research consist of the following methods and procedures:
(1) Case study methods consisting of the in-depth study of a single individual.
(2) Naturalistic observation methods in which people are observed in their normal setting with no attempt to manipulate their behavior.
(3) Certain laboratory methods in which people are observed in a laboratory setting with no attempt to manipulate their behavior.
(4) Interview methods in which participants are asked about some aspects of their lives with responses being collected and reported in essentially non-numerical terms.
It is important to note that each specific kind of qualitative research method has its advantages and disadvantages. These advantages and disadvantages have been discussed by Papalia and Olds (1992). The case study method, for example, has the advantage of providing a detailed picture of one person's behavior or development; but it has the disadvantages of possible observer bias (the observer sees what he wants to see rathe...