Objective Measurement of Subjective Phenomena
Measuring subjective phenomena is a task fraught with potential problems, but many researchers must engage in such measurement to meet a host of theoretical and practical goals. On the theoretical side, testing theories in psychology and related behavioral sciences requires us to measure personal, covert, subjective constructs. In practical applications, researchers in many different fields must have measures of subjective phenomena to answer their research questions. For example, in medical research, investigators may wish to measure pain that a patient is experiencing right now or over the past week or month, and may wish to develop a measure that is optimally responsive to treatment effectiveness. Or, researchers of cognitive and brain-related changes during aging may need measures of loneliness and perceived social support to investigate the moderating effects these constructs have on the rate of age-related change.
Although measuring subjective phenomena has attendant problems, careful consideration of the goals of measurement and of the various potential biases in measurement should ease the burden of the investigator or research team in the development of new measures. Accurate measurement begins with a careful definition of the construct to be measured and the ways in which the construct can be exemplified in behavior, emotional responses, or other ways. Items should be developed that map onto the varied phenomena associated with the construct. Potential sources of bias should be investigated. Over a half century of research in psychology has documented sources of bias in self-reports, other-reports, and observer ratings. These potential biases can be exploited in research studies to study whether scale items are systematically biased in any way; follow-up studies can be conducted to counter these biases. Once a scale has been developed, assessments of psychometric properties, such as reliability, should be conducted, and the applicability of the scale to different populations should be investigated.
The present chapter provides an introduction to the process of measuring subjective phenomena. But, the development of good, high-quality measures of subjective phenomena cannot be learned only from books, but must be learned through the process of the development and critical examination of measures. This chapter offers ways to think about examining measures for their strong and weak points and should be useful to researchers who intend to develop new measures or improve existing measures of subjective phenomena.