The following formula is involved in the calculation of adjusted R^{2} values:

Adjusted R^{2}:
where R^{2} is the sample Rsquare, k is the number of predictors, and n is the total sample size.

The following references can be used to cite this adjusted rsquare calculator (population rsquare):
 Soper, D.S. (2015). Adjusted Rsquare Calculator (Population Rsquare) [Software]. Available from http://www.danielsoper.com/statcalc 
 Cohen, J., Cohen, P., West, S.G., and Aiken, L.S. (2003). Applied Multiple Regression/Correlation Analysis for the Behavioral Sciences (3rd edition). Mahwah, NJ: Lawrence Earlbaum Associates. 