Hi, everyone. I need to do a median regression and I believe I should use the procedure iml, which I know nothing about. Below is a sample code I had found online at http://www.ats.ucla.edu/stat/sas/webbooks/reg/chapter4/sasreg4.htm and I need your help in understanding what they are. My comments are in blue color. proc iml ; /*Least absolute values*/ use elemapi2; I think elemapi2 is the dataset read all; a = cons || acs_k3 || acs_46 || full || enroll; so a is the independent variables set. cons is the constant, acs_k3, .... and enroll are all independent variables. b=api00; api00 is the dependent variable opt= { . 3 0 1 }; opt seems to mean output, but I have no idea what { . 3 0 1 } is. HELP! call lav(rc,xr,a,b,,opt); /*print out the estimates*/ what is rc and xr? Does opt mean to print out the estimates? opt= { . 0 . 1 }; opt again. { . 0 . 1 } seems to mean something different from { . 3 0 1 } . What is it? call lav(rc,xr,a,b,,opt); /*no print out but to create the xr*/ pred = a*t(xr); Calculate the predicted variable resid = b - pred; calculate the residual create _temp_ var { api00 cons acs_k3 acs_46 full enroll pred resid}; create a dataset _temp_ to contain all variables, the predicted, and the residual append; This seems to have something to do with the dataset just created quit; After this is run, the result is something like this. L1 Solution with ASE Est 17.1505029 1.2690656888 7.2240793844 5.3238408715 -0.124573396 So the Est. here is the coefficients? ASE 123.531545 6.3559394265 2.2262729207 0.602359504 0.0391932684 And these are the standard errors? I know these are really dumb questions. But I'm learning from zero. Thanks ahead for your help!
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