A Fortran Program for Correcting Correlation Coefficients for Restriction in Range for Explicit or Implicit Restriction

Abstract

Restriction in range is a measurement problem frequently encountered in research studies that utilize correlation coefficients. Statistical techniques exist to correct for this problem. In the explicit case, the restriction of the sample is based on one of the variables of interest. Therefore such restriction is direct or explicit. In the implicit case the restriction is based on a third variable which is not included in the correlation, but which is correlated with the variables of interest. A FORTRAN program is available from the authors that can compute the estimated unrestricted correlation coefficient in either the explicit or implicit case—a program using one of five formulas. The user selects the appropriate formula to be employed and supplies the appropriate restricted and unrestricted information, and the program returns the value of the corrected correlation. The program handles one correction at a time; however, it can easily be modified to handle correction of several correlation coefficients in a single run.