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Psychiatric disabilities (Major Depressive Disorder, Bipolar Disorder, Schizoaffective Disorder, Anxiety Disorders): (Kielhofner, 1998; n= 11, 10; Mean Age= 38.2, 40.3)

Raters were not formally trained, but learned by reviewing the manual and a practice rating form. Study finds minimal differences between raters, indicating that the method of learning is adequate for experienced therapists.

• All 17 raters were fit (0 misfit), indicating all valid raters
• Raters did not differ in severity/leniency of ratings (Rater separation=1.18)
• Authors suggest that the WEIS has minimal rater bias

Psychiatric disabilities: (Kielhofner et al., 1998)

• Items work well to define a unidimensional construct
• Only one item, ¡°Interaction with Others,¡± was a poor representation (infit MnSq= 1.6, Zstd=3.0) of the underlying construct
• Authors feel due to only one item being misfit, the WEIS has evidence of internal validity

Convergent validity:

Psychiatric disabilities: (Kielhofner et al., 1998)

• Average calibration for subjects (64.32) near average item calibration (50.0), indicating high construct validity
• The order of item calibration was logical
• Item calibration ranges from 42.68 to 58.03
• Person separation adequate (5.80), with reliability of 0.97
• Item separation adequate (2.77), with reliability of 0.88

Based on the items listed on the rating scale, the WEIS appears to measure the impact a work environment has on a worker. The items on the scale address factors in the work environment and how these can be enablers or barriers to work performance. (Kielhofner et al., 1998)

Sick Leave: (Ekbladh et al., 2012; n = 53; mean age = 43.0 (11) years; 34 (64%) women)
Individuals that experience sick leave due to different medical conditions. Conditions included:
Mental, behavioral disorders
Diseases of nervous system
Diseases of the eye and adnexa
Diseases of the circulatory system
Diseases of the respiratory system
Disease of the digestive system
Diseases of the musculoskeletal system and connective tissue
Symptoms, signs, and abnormal clinical and laboratory findings
Injury, poisoning and certain other consequences of external causes
***Most common diagnoses: musculoskeletal system and mental, behavioral disorders.

• The top two diagnoses included in this population include ¡°diseases of the musculoskeletal system and connective tissue¡± and ¡°mental, behavioural disorders¡± (Ekbladh et al., 2012, p. 215).
• 56 participating workers, 52 (93%) showed acceptable fit on the measurement model
• Person separation index was 2.71,which means the scale can separate the sample into at least three and almost four statistically distinct strata (3.94), which indicated three to four levels of fit between person and his or her environment. 
• ¡°Calibrated on the same continuum, the person mean measure was 0.49 (SD 0.71) and the item mean measure was 0.00 (SD 0.53)¡± ((Ekbladh et al., 2012, p. 216-217).

Sick Leave: (Ekbladh et al., 2012)

• Poor interrater reliability
• Differences in rater severity existed: (Rater Separation Index: 6.69); although this does not impact the validity of the measure, a lower rater separation index is preferred because it would indicate that the client¡¯s score is less impacted by rater.

Sick Leave: (Ekbladh et al., 2012)

• Excellent internal consistency
• MnSq. value= (.82-1.02)
• Zstd= (-1.3-.1)
• ¡°Fit statistics included the mean square standardized residual (MnSq), that is, the ratio between observed and expected scores, and the standardized mean square (ZSTD)¡± (Ekbladh et al., 2012, p. 216).
• These scores indicate that the items in the rating scale measure the same underlying construct.
• All but one item demonstrated an adequate fit. The item that was unfit was ¡°supervisor interaction¡±. This item had a MnSq value of 1.56 and a Zstd value of 3.7 (Ekbladh et al., 2012).

Sick Leave: (Ekbladh et al., 2012)

• Item calibration range: -1.14-0.92
• Higher calibrations are considered to be more challenging for the fit between the person and their work environment
• Lower calibrations are considered to be less challenging for the fit between the person and their work environment
• The highest item was ¡°Rewards¡± (0.92) and the lowest item was ¡°Interaction with Others¡± (-1.14).

• Item separation was 4.04, which implies that the WEIS separated the items into at least five different difficulty levels; the WEIS followed a hierarchical ordering so that the items demonstrated increased challenges of environmental impacts.

Based on the items listed on the rating scale, the WEIS appears to measure the impact work environment has on a worker. The items on the scale ask address factors in the work environment and how these can be enablers or barriers to work performance (Ekbladh et al., 2012).