RMSE=rooted mean squared error
MRE=min(max) relative entropy
=CORREL(A2:A4,B2:B4)^2
=SQRT(SUMPRODUCT((A2:A4-B2:B4)^2)/COUNTA(A2:A4))
=SUMPRODUCT(ABS((A2:A4-B2:B4)/A2:A4))/COUNTA(A2:A4)*100