Relationships between statistical measures of agreement: sensitivity, specificity and kappa

Objectives Cohen's kappa coefficient is presently a standard tool for the analysis of agreement on a binary outcome between two tests. In view of the ubiquity of the use of sensitivity, specificity, raw agreement and kappa in clinical studies, clearly it is advantageous to have a useful analytic relation connecting these measures of agreement. Methods We elaborate on previous work, comment on other results appearing in the literature and discuss analytic formulas relevant to various problems connecting specificity, sensitivity and kappa. Results For selected values of kappa that range from good to excellent, a graph of the curves representing minimal pairs of sensitivity and specificity is provided. Conclusions The analytic formulas and graph could be potentially useful to clinicians and biostatisticians in better interpreting the outcomes of an alternative diagnostic test whenever the measures sensitivity, specificity and kappa are employed together.