Power Function Neagtive Intercept

[Dr. N.S. Gandhi Prasad]

Hello   I have fitted a power function   Y = a (X1^b1)*(x2^b2)*(X3^b3)   by transfroming Y as well as Xs in to LOGs and followed least Squares procedure. However, the estimate of 'a' is found to be negative. Can we accept the results? What meaning can be attached to 'a'. Here Y is output and Xs are input variables   Any Comment is highly apprieciated   Gandhi Prasad   [EMAIL PROTECTED]