Читать книгу Interpreting and Using Statistics in Psychological Research - Andrew N. Christopher - Страница 39

Researchers must state explicitly not only what variables and constructs they examined, but also precisely how they measured them. An operational definition specifies the process used to measure a variable quantitatively in a research study. For instance, in Terrell and colleagues’ (2008) research, they measured narcissism using a 40-item survey that was constructed in prior research (Raskin & Terry, 1988). Table 2.2 contains four sample items from this survey. For each item that a person answers “TRUE,” he or she gets a point toward his or her total narcissism score. Scores could range from 0 to 40, with higher scores indicating higher levels of narcissism. This is the operational definition of narcissism in Terrell et al.’s (2008) research.

Table 2.2

Each item to which a person answers “TRUE” earns them one point toward their overall narcissism score. Each item to which a person answers “FALSE” earns them nothing toward their overall narcissism score.

To get a score for the variable of “narcissism,” we sum the scores for each individual item (1 for TRUE; 0 for FALSE).

Operational definition: specification of precisely how a variable is measured in a research study.

Operational definitions should be perfectly clear in any research study. They allow readers to understand precisely what was done in the study, and they allow other researchers to conduct additional research to build on prior research. Let’s take another, potentially more difficult variable to operationalize in Terrell et al.’s (2008) study. Specifically, the variable of aggressive behavior is one that could be operationalized in many ways. When psychologists discuss aggressive behavior, they focus on a person’s intention of trying to harm someone else (Baron & Richardson, 1994). Here, aggressive behavior was operationalized as the numbers of noise blasts that the participant gave an unmet other participant to harm his or her task performance. How else could aggressive behavior be operationalized? Hitting another person could qualify as aggressive behavior if the intent is to harm the person being hit. However, in this research, such an operationalization was not possible because there was no actual other participant.¹ Alternatively, aggressive behavior could have been operationalized by asking participants how much they would like to harm the other participant. Doing so would get around the fact that there was no other participant. Regardless, the important point to remember here is that however a variable is operationally defined, it must be made explicitly clear. People reading about the research study must be able to judge how good or poor the operational definition was, and other researchers need to be able to use it in their research.