The job strain measure is derived from the Job Content Questionnaire. This is a 42-item questionnaire developed by Robert Karasek, MD, PhD, based, in part, on questions drawn from the US Department of Labor/University of Michigan Quality of Employment Surveys. Two scales are used to define job strain-decision latitude and psychological demands.
The first scale, decision latitude, is defined as the sum of two subscales given equal weight:
Skill discretion, measured by six items (keep learning new things, can develop skills, job requires skills, task variety, repetitious, and job requires creativity), and decision authority, measured by three items (have freedom to make decisions, choose how to perform work, and have a lot of say on the job).
The second scale is psychological job demands, defined by five items (excessive work, conflicting demands, insufficient time to work, work fast, and work hard). All questions are scored on a Likert scale of 1 to 4, and psychological demands ranges from 12 to 48 while decision latitude ranges from 24 to 96. (In published papers from the Cornell Blood Pressure Study, a slightly different formula was used to compute the decision latitude scale score, in which the score was not multiplied by 2. Therefore, in papers from the Cornell study, the decision latitude score ranges from 12 to 48.)
The Job Content Questionnaire is copyrighted. Further information regarding the Job Content Questionnaire (referred to as the JCQ) including permission for its use and instructions for scoring, please visit their website.