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. 2012 Mar 31;24(1):15–21. [Article in Korean] doi: 10.3946/kjme.2012.24.1.15

Table 1.

Regression Equation between Point.Biserial Correlation (Cpbs) and Other Discrimination Indices

Discrimination index Equation of linear regression r2 SE F‐statistic Degree of freedom SSreg SSR
Ccit y1=1.02×Cpbs 1.00 0.00 3.74×10+30 23 0.74 0.00
Cit y3=1.04×Cpbs+0.10 0.99 0.02 351.20 23 0.87 0.06
Cbs y2=1.11×Cpbs+0.08 0.94 0.05 2,643.88 23 0.77 0.01
D y4=1.04×Cpbs+0.10 0.45 0.16 18.79 23 0.47 0.58

Ccit: Corrected item.total correlation, Cit: Item.total correlation, Cbs: Biserial correlation, D: Method of extreme group, SE: Standard error, SSreg: Sum of squared regressions, SSR: Sum of squared residuals.