Biserial-coefficient: Point-Biserial correlation coefficient
In SICSresearch/IRTpp_old: Estimating IRT parameters using the IRT Methodology

Description Usage Arguments Details Value References

Point-Biserial correlation coefficient is a correlation coefficient used when one variable is continuous and the other variable is dichotomous. License :GPL Adapted from ltm_1.0 package

1	biserial.cor(x,y)

`x`	a numeric vector representing the continuous variable.
`y`	a numeric vector representing the dichotomous variable.
`use`	Is a option for the use of missing values.
`level`	which level of y to use.

It is calculated by applying the Pearson correlation coefficient to the case where one of the variables has dichotomous nature. It is calculated as r_xy = (barx_p - barx_q / S_x)*sqrtpq where p is the proportion of subjects with one of the two possible values of the variable Y, q is the proportion of subjects with the other possible value, barx_p and barx_q is the average X subjects whose proportion is p and q respectively, and S_x is the standard deviation of all subjects X.

the value of the point-biserial correlation.

U.Olsson, F.Drasgow, and N.Dorans (1982). The polyserial correlation coefficient. Psychometrika, 47:337-347.

Cox. N.R. (1974). Estimation of the Correlation between a Continuous and a Discrete Variable. Biometrics, 30:171-178.

SICSresearch/IRTpp_old documentation built on May 9, 2019, 11:12 a.m.