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Reliability of Scales

Reliability of Measures of Job Demands and Job Decision Latitude


(“new” indicates articles published since the review article by Schnall et al., 1994 was published; reference numbers are from the review article)

In most studies where scale reliability is reported, coefficient alpha for job demands and job decision latitude is above .70. In the New York City ambulatory blood pressure study the following values were reported for men at Time 1 for job demands, job decision latitude, workplace social support, and their components:

Job Demands and 
Decision Latitude

Coefficient alpha
Workload Demands
Decision Latitude
– Skill Discretion
– Organization Influence
Composite Latitude
Social Support
– Supervisor Support
– Coworker Support
.74
.83
.75
.62
.82
.82
.92
.71

 

new. Landsbergis PA, Schnall PL, Schwartz JE, Warren K, Pickering TG. The association of ambulatory blood pressure with alternative formulations of job strain. Scandinavian Journal of Work, Environment and Health 1994;20:349-63.

In addition, Job Content Questionnaire scale reliabilities (coeffecient alpha) in a major cross-sectional study in Japan are included in:

new. Kawakami N, Kobayashi F, Araki S, Haratani T, Furui H. Assessment of job stress dimensions based on the job demands-control model of employees of telecommunication and electric power companies in Japan. International Journal of Behavioral Medicine. 1995;2(4):358-375.

 

  Men Women
Decision Latitude .68 .84
Skill Discretion .59 .80
Decision Authority .66 .68
Workload Demands .61 .65
Supervisor Support .89 .87
Coworker Support .74 .76

Four studies from Sweden as well as one from Australia and one from the U.S. have also reported values for scale reliability using a variety of scale items. These studies are:

49. Johnson, J. V., Hall, E. M. 1988. Job strain, work place social support, and cardiovascular disease: A cross-sectional study of a random sample of the Swedish working population.Am J Public Health 78:1336-42.
55. Karasek, R. A., Gardell, B., Lindell, J. 1987. Work and non-work correlates of illness and behaviour in male and female Swedish white collar workers. J Occup Behav 8:187-207.
108. Theorell TPG, Ahlberg-Hulten G, Jodko M, Sigala F, Soderholm M, de la Torre B. Influence of job strain and emotion on blood pressure in female hospital personnel during work hours. Scand J Work Environ Health 1993;19:313-318.
new. Johansson G, Johnson JV, Hall EM. Smoking and sedentary behavior as related to work organization. Soc Sci Med1991;32:837-846.
19. Chapman, A., Mandryk, J. A., Frommer, M. S., Edye, B. V., Ferguson, D. A. 1990. Chronic perceived work stress and blood pressure among Australian government employees. Scand J Work Eviron Health 16:258-69.
79. Matthews, K. A., Cottington, E. M., Talbott, E., Kuller, L. H., Siegel, J. M. 1987. Stressful work conditions and diastolic blood pressure among blue collar factory workers. Am J Epidemiol 126:280-91.

In the U.S., many studies have used the basic set of 14 items from the U.S. Quality of Employment Surveys to measure job demands (5 items) and job decision latitude (9 items). One of these studies, in addition to the New York City ambulatory blood pressure study, used subjects’ individual self-reports to measure job characteristics:

32. Green, K. L., Johnson, J. V. 1990. The effects of psychosocial work organization on patterns of cigarette smoking among male chemical plant employees. Am J Public Health 80:1368-71.

Many other U.S. studies have applied national averages of job characteristics by job title from the U.S. Quality of Employment Surveys. U.S. studies of CHD using this procedure are:

59. Karasek, R. A., Theorell, T., Schwartz, J. E., Schnall, P. L., Pieper, C. F., Michela, J. L. 1988. Job characteristics in relation to the prevalence of myocardial infarction in the US Health Examination Survey (HES) and the Health and Nutrition Survey (HANES). Am J Public Health 78:910-18.
68. LaCroix, A. Z. 1984. High demand/low control work and the incidence of CHD in the Framingham Cohort. PhD Thesis. Univ. North Carolina, Chapel Hill.
93. Reed, D. M., LaCroix, A. Z., Karasek, R. A., Miller, F. D., MacClean, C. A. 1989. Occupational strain and the incidence of coronary heart disease. Am J Epidemiol 129:495-502.
new. Alterman T, Shekelle RB, Vernon SW, Burau KD. Decision latitude, psychologic demand, job strain and coronary heart disease in the Western Electric Study. American Journal of Epidemiology1994;139:620-7.

U.S. CHD risk factor studies using this procedure are:

30. Georges, E., Wear, M. L., Mueller, W. H. 1992. Body fat distribution and job stress in Mexican-American men of the Hispanic Health and Nutrition Examination Survey. Am J Human Biol 4:657-67.
81. Mensch, B. S., Kandel, D. B. 1988. Do job conditions influence the use of drugs. J Health Soc Behav 29:169-84.
90. Pieper, C., LaCroix, A. Z., Karasek, R. A. 1989. The relation of psychosocial dimensions of work with coronary heart disease risk factors: A meta-analysis of five United States data bases. Am J Epidemiol 129:483-94.
 

Scale reliability information for scales developed from the U.S. Quality of Employment Surveys is reported in:

102. Schwartz, J. E., Pieper, C. F., Karasek, R. A. 1988. A procedure for linking psychosocial job characteristics data to health surveys. Am J Pub Health 78:904-9.

Since few studies have measured job characteristics at more than one point in time, our study at Cornell is one of the few studies (other than QES) which can provide test-retest reliability. In our sample , among men, over three years, test-retest reliability was r=0.64 for both job demands and job decision latitude — and that includes people who changed job titles (data in paper under review).

Job Strain Scales

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.

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