With Stats Master VCL it's not difficult to do complex tasks. Doing multiple linear regression is a peace of cake:

• Add MtxVecEdit, MtxVec to Uses section.
• Drop TMtxMulLinReg component and TButton on the form.
• Bring up the TMtxMulLinReg design time editor by double clicking on MtxMulLinReg1.
• Define Y, A and (optionally) Weights. You can do this at design time or at runtime (load values from file, stream...).Close TMtxMulLinReg editor.
• Double click on Button1 and add the following code:

MtxMulLinReg1.Recalculate;
ViewValues(MtxMulLinReg1.RegressResult.B,'Regression coefficients',True,False);

Other thing to try:

• Access RegressResult properties (YCalc, Residuals). Draw these values by using DrawValues method (in this case add MtxVecTee to Uses section).
• Copy Y, A data from Excel table. Repeat procedure.
• Load Y,A data from ASCII file (demonstrated in demo). Repeat procedure.