Method Variance

Method is what is used in the process of measuring something, and it is a property of the measuring instrument. The term method effects refers to the systematic biases caused by the measuring instrument. Method variance refers to the amount of variance attributable to the methods that are used. In psychological measures, method variance is often defined in relationship to trait variance. Trait variance is the variability in responses due to the underlying attribute that one is measuring. In contrast, method variance is defined as the variability in responses due to characteristics of the measuring instrument. After sketching a short history of method variance, this entry discusses features of measures and method variance analyses and describes approaches for reducing method effects.