st: Date: Fri, 27 Nov 2009 13:54:00 -0500

[Michael Crain <michaelcrain@hotmail.com>]

I have a data set of 35 observations with the predictor variable (x1) using the Likert scale and y = 0 or 1. I run -logit- and -logistic- (Stata v 10) and get a result that says:

note: outcome = x1> 3 predicts data perfectly except for
      x1 == 3 subsample:
      x1 dropped and 28 obs not used

-logit- is dropping 28 of the 35 observations and is using only 7 observations for the logit model but I don't understand the theoretical reason for doing so. 


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clear

input y x1

1 4

1 4

1 3

1 4

1 4

1 4

1 4

1 3

1 3

1 3

1 3

0 3

0 1

0 2

0 2

0 2

0 2

0 2

0 2

0 2

0 2

0 2

0 2

0 3

0 2

0 1

0 1

0 2

0 1

0 2

0 1

0 2

0 1

0 1

0 1

endscatter  y x1, jitter(5)


logit y x1

logistic y x1


 		 	   		  
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