The concept of reliabilityWe use the word ‘reliable’ very often in our lives. When we say that a person is reliable, what do we mean? We infer that s/he is dependable, consistent, predictable, stable and honest. The concept of reliability in relation to a research instrument has a similar meaning: if a research tool is consistent and stable, hence predictable and accurate, it is said to be reliable. The greater the degree of consistency and stability in an instrument, the greater its reliability. Therefore, ‘a scale or test is reliable to the extent that repeat measurements made by it under constant conditions will give the same result’ (Moser & Kalton 1989: 353). The concept of reliability can be looked at from two sides: 1. How reliable is an instrument? 2. How unreliable is it?