Measurement in Marketing

7Validity of a Measurement Scale

OBJECTIVES OF THE CHAPTER.–

This chapter discusses the validity of a measurement scale from several angles. Its objectives are to:

• ‒ present the main aspects of the validity of a measurement scale;
• ‒ pinpoint the scope of each type of validity for achieving an appropriate measuring instrument;
• ‒ present the main approaches for the construct validity of a reflective scale;
• ‒ distinguish the different concepts associated with the validity of a measurement scale;
• ‒ guide the validation protocols of a measurement scale.

7.1. Introduction

The reliability test is used to reveal if the items are consistent, but does not reveal if they are valid. Admittedly, reliability is an essential condition for assessing the qualities of a measure, especially its validity, but it is insufficient to ensure it. “Validity refers to the degree to which instruments truly measure the constructs which they are intended to measure” (Peter 1979, p. 6), which is a central concern when choosing or developing a scale. This means checking the level of appreciation of the value of the construct given by the measurement aside from random and systematic errors. In the absence of such an examination, it is almost impossible to predict whether the absence or even the presence of a theoretical link between two constructs, through a set of measures, is a result that can be trusted to capture reality. Thus it is all the more regrettable to invest time, effort and costs without ...