C

I'm doing a research on the estimation of "Tunnel Cost" for which I carried out some regression analysis based on data of 30 tunnel projects implemented in the USA. The dataset consists of recorded tunnel construction cost and tunnel size (i.e., tunnel diameter and length). the results of the regression analysis results showed that better correlation coefficient (R2) is obtained when the log10 of parameters are used, i.e., tunnel depth and diameter. below are some of my results for further detail.

Cost(M£)=10^(3.052+3.905Log(L*)+0.867Log(D**).................R2= 0.95 ....................(1)

Cost(M£)=-301.43+53.249(L*)+ 9.341(D**).......................R2= 0.80......................,...(2)

*L is tunnel length in (km), and **D is tunnel diameter in (m)

My question is what do these results statistically mean , I mean having higher correlation coefficient with log10 of the independent variables than their normal values what does statistically mean? Can you please explain this for me , I have tried to find out what are these results statistically mean but could not find any proper explanation for these results!

Thank you very much in advance for your help and support.

Best regards,