Information AboutPoint-biserial Correlation Coefficient |
| CATEGORIES ABOUT POINT-BISERIAL CORRELATION COEFFICIENT | |
| covariance and correlation | |
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The point-biserial correlation is mathematically equivalent to the Pearson (product moment) Correlation , that is, if we have one continuously measured variable ''X'' and a dichotomous variable ''Y'', rXY = rpb. This can be shown by assigning two distinct numerical values to the dichotomous variable. To calculate rpb, assume that the dichotomous variable ''Y'' has the two values 0 and 1. If we divide the data set into two groups, group 1 which received the value "1" on ''Y'' and group 2 which received the value "0" on ''Y'', then the point-biserial correlation coefficient is calculated as follows: : where is the mean value on the continuous variable ''X'' for all data points in group 1 and is the mean value on the continuous variable ''X'' for all data points in group 2. Further, is the number of data points in group 1, is the number of data points in group 2 and is the total sample size. This formula is a computational formula that has been derived from the formula for rXY in order to reduce steps in the calculation - it is easier to compute than rXY. It is of much less importance these days since computers are almost exclusively used for statistical data analysis. EXTERNAL LINKS Notes |
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