Measures of Interrater Agreement for Quantitative Scales Based on the Standard Deviation

Interrater agreement for measurements on quantitative (discrete or continuous) scales is usually evaluated by overall measures across targets (subjects or objects) like the intraclass correlation coefficient. In this paper, a new index that allows to evaluate the agreement between two or more raters for each single target is presented, and a global measure for the whole group of targets is obtained as the arithmetic average of the single values. Some advantages of the proposed indices are highlighted by an application related to the measurement of tumor sizes.