CombiStatX is a programm that lets you carry out two useful statistical procedures. Firstly, you can combine several MeanąSEM values into an overall MeanąSEM. Secondly, you can calculate the Standard error (SE) and Standard deviation (SD) of the ratio (X/Y), product (X*Y), sum (X+Y), and difference (X-Y) of the mean values (X and Y) of two independent variables, x and y, each with an associated SEM.