Question

In regards to items and scales why is reliability and validity important. Please provide various types of validity in answer.

Answer 1

Reliability and validity are both very important criteria for analysing the quality of measures. Although they are independent aspects, they are also somewhat related. A measurement procedure cannot be valid unless it’s reliable however, a measurement can be reliable without being valid (someone could measure your height and say they are measuring intelligence, they would get a consistent and reliable result each time but this would NOT be valid since height is not an indicator of intelligence). In psychological research there is rarely an established standard for measurements. For instance it is hard to analyse how accurate a depression measure is since there is no official unit of depression, therefore validity and reliability substitute this problem. Without reliability and validity it would be very difficult to decide which research should be trusted and which should be completely disregarded.

In all, reliability and validity are important factors of psychological research studies. They allow us to gain firm and accurate results, as well as helping us to generalize our findings to a wider population and, in turn, apply research results to the world to improve aspects of people’s lives.

Various types of validity-

Validity is further identified as either internal or external. Internal validity refers to the ability of the research design to rule out alternative explanations of the results (Marczyk, DeMatteo & Festinger, 2005). High degrees of internal validity are associated with experimental design, where the effect of an independent variable on a dependent variable is studied under strictly controlled conditions. Medical research and clinical trials are widely used examples of experimental design.

External validity concerns generalizability of the research findings. In other words, if the study is repeated in a different place or with different people, would the results be the same? A key factor for ensuring external validity is obtaining a sample that is representative of the population being studied.