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st: collinearity/non-convergence problem with -asclogit- command


From   Cielo Magno <cielomagno@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: collinearity/non-convergence problem with -asclogit- command
Date   Mon, 12 Oct 2009 20:08:35 -0400

Hello everyone,

I am hoping someone will be able to help me with my problem. I am new
with Stata and I am trying to run the -asclogit- command. The model
always results in non convergence because of collinear variables.

I want to start with a simple model, just 1 alternative-specific
variable and 1 case-specific variable but I can’t even get pass it.
This is the command I am using:

. asclogit choice price2, casevars(age) case (id) alternative (alter) iter(5)

This is how my data looks like.  There are 11 products, my
alternative-specific variables are the price of the product and the
amount of money they spent on advertising every month.

I tried to replace price2 with the advertising variable and the result
is still the same.  I also tried creating a dichotomous variable (by
transforming my advertising variable into a dichotomous yes/no
variable) and using it as the alternative-specific variable but the
result is the same – non convergence.


+-----------------------------------------------------+
     | choice   	price2   age   id    	alter   	total_ads |
     |-----------------------------------------------------|
  1. |      1      	110	83   33      	product1    15488033 |
  2. |      0       	92  	83   33      	product2    11891267 |
  3. |      0	                101	83   33    	product3    0 |
  4. |      0       	77    	83   33      	product4    0 |
  5. |      0       	82    	83   33   	product5  	49783.33 |
  6. |      0      	104    	83   33       product6   	27916.67 |
  7. |      0      	122    	83   33   	product7    21012.50 |
  8. |      0      	168    	83   33    	product8   166.67 |
  9. |      0 	                 107    	83   33     	product9    0 |
 10. |     0       	 58    	83   33   	product10  0 |
 11. |     0      	153    	83   33      	product11  0 |
     |-----------------------------------------------------|
 12. |      1      	110 	61   37   	product1    15488033 |
 13. |      0       	92    	61   37      	product2    11891267 |
 14. |      0      	101    	61   37    	product3    0 |
 15. |      0       	77    	61   37       product4    0 |
 16. |      0       	82    	61   37   	product5   	49783.33 |
 17. |      0      	104    	61   37       product6   27916.67 |
 18. |      0      	122    	61   37   	product7    21012.5 |
 19. |      0      	168    	61   37    	product8   166.67 |
 20. |      0      	107    	61   37     	product9    0 |
 21. |      0       	58    	61   37   	product10  0 |
 22. |      0      	153    	61   37      	product11  0 |
     +-----------------------------------------------------+


I can’t figure out/find a solution to my problem.  I am using Stata/IC
11.0 and it is updated.  Any help will be greatly appreciated.
Thank you very much.


Cielo Magno
Graduate student
Law, Policy & Society
Northeatern University

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