Assessing psychometric scale properties

Assessing Psychometric Scale Properties of Patient Safety Culture... 

Both CTT and IRT can, and should, be used to assess the psychometric properties of a scale. Each proposes ways of conceptualising dimensions of safety cirlture and specifies how they relate to observed scores. The central focus of CTT is the trae score on the test, which is the expected value of the observed test score over an infinite number of trials. A primary goal of test developers is to minimise random error around the true score by aggregating scores across several related items. If such a set of items is successfully identified by EFA and CFA, correlations between items are consistent and moderately high. 

Factor loadings are presented in Table 2 below. All the factor loadings are high, which indicates that indeed all the observed variables are correlated to the factors investigated in this study. In other words, the psychometric properties of the scales that were used to assess Systemizing, Teacher Support, Anxiety and Intrinsic Motivation are good. Furthermore, these scales are invariant across gender (female versus male) and eultures (Canadian versus Swedish). 

The Standard Shiftwork Index was developed in response to a perceived lack of standardization in the assessment of shiftwork. The solution is a set of scales that reflect the most pertinent issues within shiftwork research. .. chosen on the basis of being both relatively short, easy to administer, and having good psychometric properties (Barton et al., 1995). The scales are grouped into those that access data on outcomes (e.g., actual shiftwork problems), those that refer to modifiers (e.g., individual differences), and a set of general scales (e.g., shiftwork context). 

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