Introduction to Psychometrics/Reliability.

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Introduction to Psychometrics/Reliability

1. Introduction

Psychometrics is about the measurement of psychological constructs such as intelligence, people's attitudes and interests, and people's behaviour based upon the systematic application of a few relatively simple principles. And measurement has proved to be extremely important in science. Measurement is at the heart of the scientific method used in psychology.

2. Definitions

Abstract concepts like social status or intelligence we call constructs, the concrete representations of these constructs we call variables (e.g. income, GCSE results) and the procedures for measuring variables we call operational definitions (e.g. actual questions used and the methods for administering and scoring these tests).

Constructs are the abstractions scientists use in discussing theories (e.g. social power, intelligence, dietary restraint, attitude). Sometimes constructs are referred to as latent variables. Here the term latent indicates the fact that the variable must be inferred from other observable variables. Hence, constructs (or latent variables) can only be inferred from the relationship between sets of stimuli and sets of responses. For example, racist attitudes are inferred from the relationship between stimuli such as individuals of a particular skin colour or religious belief and observable expressions of negative feelings or behaviours