Date:         Mon, 31 Dec 2007 14:11:52 -0600
Reply-To:     Mary <mlhoward@avalon.net>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Mary <mlhoward@AVALON.NET>
Subject:      Re: Regression where dependent variable has an upperbound
Comments: To: Xu Zeng <xuzeng@HOTMAIL.COM>
Content-Type: text/plain; charset="iso-8859-1"

Xu Zeng,

Is it really necessary to do this within the logistic regression procedure?  Why couldn't you save the predicted values, merge them to the actual values, and then in a data step adjust any values that are over the owed amount to the owed amount, like this?

data new;
/* merge {predicted and actual } */

if predicted_owed_amount > actual_owed_amount then
  do;
      predicted_owed_amount=actual_owed_amount;
  end;


-Mary
  ----- Original Message ----- 
  From: Xu Zeng 
  To: SAS-L@LISTSERV.UGA.EDU 
  Sent: Friday, December 28, 2007 9:10 AM
  Subject: Regression where dependent variable has an upperbound


  I am trying to predict dollar amount collected for people who have various
  debts. But this dependent variable can never exceed the original amount of
  debt people owe. For example, if someone owes $5000 then the predicted
  collected $ must be <=5000 (I am not considering interests for simplicity).

  I will definitely use the original owed amount as one of independent
  variabls and the coefficient of it will be less than 1 (in a linear
  regression). But I will probably have many other variables, I can't 100%
  sure that the predicted amount will be less than original debt amount. Of
  course, I can adjust the prediction at the end, but I would like to know if
  there is a SAS regression procedure or statistical method that will
  guarantee the prediction never exceeds the upperbound.

  Your advice and suggestion will be greatly appreciated.

  Thank you very much and happy new year.