Exponential distribution of total depressive symptom scores in relation to exponential latent trait and item threshold distributions: a simulation study

BMC Research Notes

Yohei Kawasaki¹  Kazuki Ide²  Hiroshi Yamada²  Maiko Akutagawa²  Toshiaki A. Furukawa³  Shinichiro Tomitaka⁴ 

[1] Clinical Research Center, Chiba University Hospital;Department of Drug Evaluation and Informatics, School of Pharmaceutical Sciences, University of Shizuoka;Department of Health Promotion and Human Behavior, Department of Clinical Epidemiology, Kyoto University Graduate School of Medicine/School of Public Health;Department of Mental Health, Panasonic Health Center;

关键词: Depressive symptom;    Latent trait;    Simulation;    Ordinal scale;    Exponential distribution;    CES-D;   

DOI  :  10.1186/s13104-017-2937-6

来源: DOAJ

【 摘 要 】

Abstract Objectives Total depressive symptom scores in the general population have been reported to follow an exponential distribution except at the lowest end of the range of scores. To verify the hypothesis that total depressive symptom scores follow the distribution of the latent trait, we performed a simulation study of depressive symptom scoring modeled after the Revised Clinical Interview Schedule (CIS-R). To simulate the scoring of ordinal scale items in CIS-R, two sets of random numbers were generated, one expressing the degree of the latent trait of depressive symptoms and another expressing the threshold for each item. Random latent trait numbers greater than those of item thresholds indicated the presence of specific symptoms. Results When exponential distribution was set to the latent trait’s random numbers and each item’s threshold had a certain degree of standard deviation, simulated total depressive symptom scores showed a linear pattern except at the lowest end of scores with a log-normal scale. Our results suggest that total depressive symptom scores follow the distribution of the latent trait of depressive symptoms due to the property of ordinal scales, which is characterized by individual differences in the threshold of each item.

【 授权许可】

Unknown