Bmc Med Res Methodol
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Bmc Med Res Methodol · Jan 2013
A comparison of Cohen's Kappa and Gwet's AC1 when calculating inter-rater reliability coefficients: a study conducted with personality disorder samples.
Rater agreement is important in clinical research, and Cohen's Kappa is a widely used method for assessing inter-rater reliability; however, there are well documented statistical problems associated with the measure. In order to assess its utility, we evaluated it against Gwet's AC1 and compared the results. ⋯ Based on the different formulae used to calculate the level of chance-corrected agreement, Gwet's AC1 was shown to provide a more stable inter-rater reliability coefficient than Cohen's Kappa. It was also found to be less affected by prevalence and marginal probability than that of Cohen's Kappa, and therefore should be considered for use with inter-rater reliability analysis.
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Bmc Med Res Methodol · Jan 2013
Flexible parametric modelling of cause-specific hazards to estimate cumulative incidence functions.
Competing risks are a common occurrence in survival analysis. They arise when a patient is at risk of more than one mutually exclusive event, such as death from different causes, and the occurrence of one of these may prevent any other event from ever happening. ⋯ A key advantage of using this approach is that smooth estimates of both the cause-specific hazard rates and the cumulative incidence functions can be obtained. It is also relatively easy to incorporate time-dependent effects which are commonly seen in epidemiological studies.