Factorial design is applied in the analysis of global solar radiation in eight selected stations in Nigeria. The analysis of coefficient of determination and adjusted coefficient of determination ranges between 0.9768(Ibadan) to 0.9965(Calabar) and 0.9361(Ibadan) to 0.9905(Calabar) respectively. The model equation using the 23- factorial design could be used for prediction of global solar radiation on both short- and long –term bases. The values of mean absolute errors (MAE) and the root-mean –square errors (RMSE) calculated shows the applicability of the factorial design for the analysis of global solar radiation in Nigeria.
