Introduction

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Many of the variables that we study in psychological research cannot be directly observed. Intelligence, creativity, depression, memory, interpersonal attraction -- these are phenomena studied in psychology but none of them can be directly known through our senses. We cannot hear interpersonal attraction or touch intelligence or see memory. We consider such phenomena to be theoretical concepts. The science of psychology tries to develop explanations of theoretical concepts through objective observations.

Why Is This Important?
Because the meaning of our study rests on how we objectively observe our theoretical constructs, developing a reliable and valid set of procedures for measuring our variables is crucial in any research study. To do this, we must first specify our construct. Good preoperational specification of constructs follows a series of steps:

1. Develop a conceptual definition
2. Specify the dimensions of the construct
3. Choose a method of measurement
4. Select specific operations

All of these procedures together are part of specifying a theoretical construct. Let's apply these steps to the construct of post-traumatic stress disorder (PTSD).