[Limdep Nlogit List] standard deviation

[Cyrus Levy]

What am I doing wrong with the following code? Could you please help me?

reset;
create; var=-0.9 $
dstat; rhs = var $
sample; 1-10 $
dstat; rhs = var $

With this code, I create a variable (var) which is equal to -0.9 everywhere.
Then I check the descriptive statistics of the variable but the standard
deviation is not equal to 0 and it's positive. Then I set the sample to the
first 10 observations and look at the descriptive statistics again, and the
standard deviation changes but it's still not equal to 0. Could you please
tell me what's wrong with my code? Is it due to calculation precision? Can I
change it?


--> reset;
Initializing NLOGIT Version 4.0.1 (January 1, 2007).
--> create; var=-0.9 $
--> dstat; rhs = var $
Descriptive Statistics
All results based on nonmissing observations.
===============================================================================
Variable     Mean       Std.Dev.     Minimum      Maximum        Cases
Missing
===============================================================================
------------------------------------------------------------------------------
All observations in current sample
------------------------------------------------------------------------------
VAR     | -.900000      .639559E-13 -.900000     -.900000         4524
0
--> sample; 1-10 $
--> dstat; rhs = var $
Descriptive Statistics
All results based on nonmissing observations.
===============================================================================
Variable     Mean       Std.Dev.     Minimum      Maximum        Cases
Missing
===============================================================================
------------------------------------------------------------------------------
All observations in current sample
------------------------------------------------------------------------------
VAR     | -.900000      .117028E-15 -.900000     -.900000           10
0