Should you use normalized or non-normalized data to develope your model?

I am developing a linear model with 13 variables, including the target variable (online purchase revenue for items). So, I first built model1 with regular variable and then build model2 after normalizing of the data. I have copied the coefficients for two models here :

Model1(Without Normalized Data)
Coefficients:
6.386e+01                 -4.301e-03                 -1.229e+02
1.239e+02                  7.788e-02                 -1.424e+02
xcardtremovetotal        xcardtremovetotalrs              xproductviews
5.588e+02                 -3.445e-02                  1.369e+01
xuniqprodview              xprodviewinrs       xsizeselecteduniview
-1.530e+01                  5.401e-04                 -1.299e+02
xsizeselectedtotalviews  xsizeselectedtotalviewsrs
6.280e+01                 -2.453e-02

Model 2(With Normalized data)
Coefficients:
(Intercept)                          xid
3.900e+02                   -4.301e-03
-2.623e+03                    2.069e+03
1.785e+03                   -1.721e+02
xcardtremovetotal_n        xcardtremovetotalrs_n
4.474e+02                   -5.360e+01
xproductviews_n              xuniqprodview_n
7.979e+03                   -7.378e+03
xprodviewinrs_n       xsizeselecteduniview_n
4.757e+02                   -1.218e+03
xsizeselectedtotalviews_n  xsizeselectedtotalviewsrs_n
1.044e+03                   -5.374e+02


and my questions are :

1. Is it appropriate to take only normalized data into model or non normalized data?

2. Is it appropriate to take combination of normalized data as well as non normalized data?

3. How can I choose most appropriate predictor variable from them for model?

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What is your question? –  Michael Chernick Sep 1 '12 at 12:03
should i have to consider normalized value in model or not? –  ViGnEsH Sep 1 '12 at 12:14

The difference between using normalized and nonnormalized data is one of interpretation. If you use the original data, the coefficients apply to changes of one unit on the original scale. If you use the normalized data, they apply to changes of one unit on the new scale (usually, one standard deviation).

This is an issue on which there is no universal agreement among statisticians. My own tendency is to use unstandardized data. However, the two models really mean the same thing.

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thanks Peter Flom, but suppose if i am using combination of normalized data and un-normalized data. so is it same thing? –  ViGnEsH Sep 3 '12 at 7:00
Yes, but it can get confusing. –  Peter Flom Sep 3 '12 at 10:43