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Concepts of reliability and validity in social science research are introduced and major methods to assess reliability and validity reviewed with examples from the literature. The thrust of the paper is to provide novice researchers with an understanding of the general problem of validity in social science research and to acquaint them with approaches to developing strong support for the validity of their research.
Introduction
An important part of social science research is the quantification of human behaviour - that is, using measurement instruments to observe human behaviour. The measurement of human behaviour belongs to the widely accepted positivist view, or empiricalanalytic approach, to discern reality (Smallbone & Quinton, 2004). Because most behavioural research takes place within this paradigm, measurement instruments must be valid and reliable. The objective of this paper is to provide insight into these two important concepts, and to introduce the major methods to assess validity and reliability as they relate to behavioural research. The paper has been written for the novice researcher in the social sciences. It presents a broad overview taken from traditional literature, not a critical account of the general problem of validity of research information.
The paper is organised as follows. The first section presents what reliability of measurement means and the techniques most frequently used to estimate reliability. Three important questions researchers frequently ask about reliability are discussed: (1) what affects the reliability of a test?, (2) how can a test be made more reliable?, and (3) what is a satisfactory level of reliability? The second section presents what validity means and the methods to develop strong support for validity in behavioural research. Four types of validity are introduced: (1) statistical conclusion validity, (2) internal validity, (3) construct validity and (4) external validity. Approaches to substantiate them are also discussed. The paper concludes with a summary and suggestions.
Reliability
Reliability is a major concern when a psychological test is used to measure some attribute or behaviour (Rosenthal and Rosnow, 1991). For instance, to understand the functioning of a test, it is important that the test which is used consistently discriminates individuals at one time or over a course of time. In other words, reliability is the extent to which measurements are repeatable - when different...