st: loop problem?

["Jun Xu" <mystata@hotmail.com>]

I think I might not have explained my problems clearly.  I have k indicator 
variables (coded as 1 or 0) and I would like to know the response patterns 
(for example for latent class analsis) to these k variables.  For example,

var1 var2 var3 ....vark
1    0    0         0
0    1    0         0
...
1    1    0         0
...
...
...
1    1    1         1

I would like to know for each response pattern, how many cases are there, 
and programmed into an ado file.  My key problem here is how to run through 
all the combinations (univariate, bivariate, and trivariate)

One posibility is that I used the following cods (or reviced version to fit 
into an ado file)

******************************************************************
clear
for num 1/6: set obs 100\ gen xX=invnorm(uniform()) \ gen DxX=xX>0.6
gen pattern=0
local i=1
while `i'<6 {
	replace pattern=pattern+Dx`i'*10^(6-`i')
	local i=`i'+1
}

aorder
list Dx1-Dx6 pattern
sort pattern
list pattern
gen count=1
collapse (sum) count, by(pattern)
***********************************************************
The resulting data matrix looks like:

============================
pattern	count
0	16
10	10
100	5
110	6
1000	8
1010	7
1100	2
1110	1
10000	11
10010	3
10100	2
10110	2
11000	2
11010	2
11100	1
100000	7
100010	1
100100	2
101000	4
101010	1
110000	1
110010	2
110100	2
111000	1
111010	1
=================================


Here the problem is that it only presents the response pattern that has at 
least one case and it's hard to handle its order (now is list in numerical 
order: from small to big)
But what if I want to go through "each" combination (2^k possible ways) in a 
sysmatic way and list all response pattern freqeuncy though some of them 
have zero cases.  What I meant by a systematic way is like:

*********************************************************************
var1
var2
var3
...
...
...
vark
var1 var2
var1 var3
var1 var4
...
...
var1 vark
var2 var3
var2 var4
...
...
var(k-1) vark
...
...
var1 var2 var3
var1 var2 var4
var1 var2 var5
...
var1 var2 var3....vark
******************************************************************

or in binary coding
****************************************************************
1 0 0 0 0 .....0
0 1 0 0 0 .....0
0 0 1 0 0 .....0
...
...
...
0 0 0 0 0 .....1
1 1 0 0 0 .....0
1 0 1 0 0 .....0
1 0 0 1 0 .....0
...
...
1 1 1 0 0 .....0
1 0 1 1 0 .....0
...
...
...
...
1 1 1 1 1 .....1
***********************************************

Here I didn't present some summarize command that could grab case number for 
that response pattern.  But basically I will run through each combination 
and calculate the frequency for that particular combination though there 
might be zero cases.  Thanks a lot


Jun Xu
Department of Sociology
Indiana University at Bloomington





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