Chapter 8Measurement of

Variables

Chapter Objectives

• Operationally define (or operationalise) concepts

• Explain the characteristics and power of the four types of measurement scale — nominal, ordinal, interval and ratio

Research Design: Measurement and Measures

How Variables are Measured

• Objective data– Eg weight, absenteeism, temperature

• Use appropriate measuring instruments

• Subjective data– Eg feelings, attitudes, perceptions

• Operationalise the concept

Operational Definition

Is a statement of the specific dimensions and elements through which a concept will become measurable.

Dimensions (D) and Elements (E) of the Concept (C) ‘Achievement Motivation’

Examples of Questions to Tap the level of ‘Achievement Motivation’

1. To what extent would you say you push yourself to get the job done on time?

2. How frequently do you think of your work when you are at home?

3. How much do you concentrate on achieving your goals?

4. How annoyed do you get when you make mistakes?

Common Mistakes with Operational Definitions

• Excluding some of the important dimensions and elements

• Arising from failure to recognise or conceptualise them

• Including certain irrelevant features mistakenly thought to be relevant.

What an Operational Definition is Not

• An operational definition does not consist of delineating the reasons, antecedents, consequences or correlates of the concept

• Rather, it describes its observable characteristics in order to be able to measure the concept.

Dimensions (D) and Elements (E) of the Concept (C) ‘Learning’

Measurement Scales

• Nominal Scale

• Ordinal Scale

• Interval Scale

• Ratio Scale

Nominal Scale

Nominal Scale

• Splits data into mutually exclusive and collectively exhaustive categories– Eg, men, women

Ordinal Scale