EWPS (Endicott Work Productivity Scale) is a questionnaire, usually brief and established for enabling investigators to acquire sensitivity in measuring work productivity. The survey performs computations from the best value usually 0 to the worst value, 100, and is composed of 25 items on a 5-point, normally measured on a Likert scale. The rating of the 25 items is usually done on the scale containing 5 points considering how often the attitude, behavior and feeing has been portrayed. The tool is based on 4-dormains of productivity that is attendance, performance capacity, quality of work and personal factors. The paper explores the psychometric properties of EWPS and explains when it is appropriate to use the tool with the clients. Besides, the paper also discusses whether the tool can be used in evaluating the efficacy of psychopharmacologic medications.
Psychometric properties refers to the validity and reliability of a clinical tool. An instrument such as EWPS is expected to show accuracy in its measurements. The reliability of EWPS assists in obtaining a valid assessment while its validity helps in making a confident prediction. To determine the psychometric properties of a tool, one must conduct a study to determine the instrument’s validity and reliability, since these two are the principal measures of psychometry. The Psychometric properties also depend upon the pay scale and living standards of the respected country. For instance, Uguz et.al (2014) conducted a research to determine the validity and reliability of EWPS of Turkish version. Two discrete groups, a community sample (n=107) and a patient group (n=74) were utilized in the study. Translation of the initial form was done to Turkish and then to English through the adaptation process.
The research conducted by Uguz et.al (2014) obtained a Cronbach’s alpha (internal consistency) coefficient of >.90 for both groups. Individual item correlation with the overall scores of EWPS ranged from .32 to .75. The patient group showed EWPS and HAM-D scores which were positively correlated that is r=.52 and r=.62. CGI gave a score of .64 and social functioning subscale, SF-36 showed negative correlation (r= -.43). Uguz et.al (2014) obtained test-retest scores correlation of EWPS as .76. The total scores of the community and the patients showed a significant mean difference. In conclusion, the study found the EWPS from Turkey to be reliable and valid. These findings related to validity and reliability of EWPS indicates the psychometric properties of this instrument can be utilized in researches that will be carried out in Turkey.
It is most appropriate to use the tool with clients when an investigator needs to acquire sensitive measure on the productivity of work. In this case, the total score is calculated on the basis on the extent to which subjective feelings, behaviors or attitudes that have probability of reducing efficiency and productivity in work activities characterize the subject in a period of time before the evaluation. Most of the studies in assessing the treatment effects shows validity and reliability and validity of the total score in both the group under question and the control group. The EWPS score is usually related to, but not redundant with the measures of the overall cruelty of the sickness and harshness of depression in the samples. The EWPS is promising because most of its results portray the instrument as a sensitive, brief and commonly used tool for the assessment of the impacts on the performance of work of various diseases and the efficacy of various therapeutic interventions. As a consequence, the instrument can be used to evaluate the efficacy of psychopharmacologic medications.