
Hi everyone, I am writing this to get  your help. I have a big data set and I wanted to do multiple regression and repeat this process several timesfor example (data)where y: dependent variables ; number of columns are 5, nrow = 1800y   temp, preci, growing season days, max temp, min temp region4   23     0        127                             35           14         NORTH AMER10  35    21       120                             32          17         NORTH AMER1   18     1        90                               27            12        EUROPE...........    
1) here I wanted to do linear regression (simple regression) using each predictor (temp, preci, growing season days, max temp... etc), separatelyafter that, I want to  second  quadratic regression using each predictor, and third - polynomial (cubic)2) I wanted to compare the models (linear, quadratic and cubic) and chose the best model 3) I wanted to do multiple regression using the best model of each variable Further, I wanted to divide the data into groups by region. and, then perform the above analysis for each group (by region)and, I wanted to compare the residuals between the models where I have been using all data set and the models by region
I was trying to do manually, but it is taking so much time. I think it is not difficult and does not take time to write script in R.  I was trying to make loop but I could not succeedI would be very grateful if you help me how I can write script (loop function) and compute the analysis in R. Thanks for your support. 
Sincerely, 
Kristi GloverUniversity of Windsor, Windsor, Canada


 		 	   		  
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