Peirce's 𝑖 and Cohen's 𝜅 for 2×2 Measures of Rater Reliability

Table 1

Descriptive statistics of $i$ and $\kappa$.

	Peirce’s i		Cohen’s κ
Parameters $(n,i,j)$	Mean	SD	Mean	SD
$\tau =.5$
$500,.5,.5$	.50	.03	.50	.03
$100,.5,.5$	.50	.07	.50	.07
$25,.5,.5$	.50	.14	.49	.14
$500,.7,.5$	.70	.03	.70	.03
$100,.7,.5$	.69	.06	.69	.06
$25,.7,.5$	.70	.11	.69	.11
$\tau =.7$
$500,.5,.5$	.50	.04	.46	.03
$100,.5,.5$	.50	.08	.45	.08
$25,.5,.5$	.50	.18	.45	.17
$500,.7,.5$	.70	.03	.66	.03
$100,.7,.5$	.70	.06	.66	.06
$25,.7,.5$	.71	.13	.65	.14
$500,.5,.9$	.50	.02	.55	.02
$100,.5,.9$	.50	.05	.55	.05
$25,.5,.9$	50	.11	.55	.11
$\tau =.9$
$500,.5,.5$	.50	.05	.27	.04
$100,.5,.5$	.50	.12	.26	.08
$25,.5,.5$	.48	.31	.27	.17
$500,.7,.5$	.70	.04	.46	.04
$100,.7,.5$	.70	.10	.45	.10
$25,.7,.5$	.70	.21	.45	.18