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Method comparison studies consist of a unique study design aiming to examine agreement between two methods to measure a physiological or clinical parameter evaluated using continuous variables. Such physiological parameters are used by healthcare providers along with other clinical data to inform diagnoses and treatment decisions. When novel methods are proposed to measure a continuous physiological parameter, method comparison studies are needed to examine the agreement between this new method and an existing method that is used in standard clinical care. This standard method is generally considered as the gold standard measurement for a given physiological parameter. The issue of repeated measurements poses special challenges when conducting method comparison studies. Repeated measurements occur when a given individual included in a method comparison study has multiple measurements, which are inherently correlated with one another and are not independent (e.g., multiple glucose measurements carried out for the same patient throughout the day using a blood test, compared to a portable point-of-care device). The limits of agreement (LOA) method proposed by Bland & Altman has been adapted to adjust for the correlation between repeated measurements and is widely used for the analysis of method comparison studies that include repeated measurements. However, other statistical methods have been proposed as alternatives to LOA analysis to inform the analysis of method comparison studies with repeated measurements. There is a gap in the literature to inform this type of analysis, whereby no guidelines or synthesis of statistical methods that can be used as alternatives to the LOA method with repeated measurements have been published. Therefore, this thesis aimed to systematically review the existing literature to identify existing alternate statistical methods for the analysis of method comparison studies that include repeated measurements, using a scoping review framework. The findings of this scoping review were used to inform the analysis of the PREMISE (Point-of-care hemoglobin accuracy and transfusion outcomes in non-cardiac surgery) study, a large prospective observational method comparison study that included repeated measurements. The aim of the PREMISE study was to examine the agreement between frequently used point-of-care devices to measure hemoglobin (POCT-Hgb) and laboratory-measured hemoglobin (lab-Hgb) in the operative setting. To further increase the understanding of the challenges associated with the analysis of method comparison studies that include repeated measurements, the analyses pertaining to agreement were performed in the context of this thesis. The findings of the PREMISE study fill an important gap in the literature pertaining to transfusion decision-making in the operative setting, where there is a paucity of evidence on the accuracy of POCT-Hgb devices, as well as from trials and transfusion guideline.

Despite the importance of job specifications to much of industrial and organizational psychology, little is known of their reliability or validity. Because job specifications are developed based on input from subject matter experts, interrater agreement is a necessary condition for their validity. The purpose of the present research is to examine the validity of job specifications by assessing the level of agreement in ratings and the effects of occupational tenure, occupational complexity, and the abstractness of rated worker requirements. Based on the existing literature, it was hypothesized that (1) agreement will be worse than acceptable levels, (2) agreement will be higher among those with longer tenure, (3) agreement will be lower in more complex occupations, (4) the effect of occupational tenure will be more pronounced in complex than simple occupations, (5) agreement will be higher on more abstract items, and (6) agreement will be lowest for concrete KSAOs in complex occupations. These hypotheses were tested using ratings from 38,041 incumbents in 61 diverse occupations in the Federal government. Consistent with Hypothesis 1, agreement failed to reach acceptable levels in nearly every case, whether measured with the awg or various forms of the rwg agreement indices. However, tenure, occupational complexity, and item abstractness had little effect on ratings, whether agreement was measured with rwg or awg. The most likely explanation for these null findings is that the disagreement reflected a coarse classification system that overshadowed the effects of tenure, complexity, and abstractness. The existence of meaningful subgroups within a single title threatens the content validity of job specifications: the extent to which they include all relevant and predictive KSAOs. Future research must focus on the existence of such subgroups, their consequences, and ways of identifying them. / Ph. D.