topic Re: Output full matrix of tetrachoric correlations in Statistical Procedures

Output full matrix of tetrachoric correlations

awesome_opossum — Tue, 20 Sep 2022 18:05:29 GMT

Hi, I'm trying to output a full matrix of tetrachoric correlations, like the matrix produced by proc corr outp= option.

Proc corr does have an option for outputting tetrachoric correlations:

proc corr data = data polychoric;
var var1 var2 var3 var4;
ods output PolychoricCorr = tcorr;
run;

However, it outputs the data like so:

I've heard there are macros out there that can do this, but I'm wondering if there's maybe a simpler solution or other procedure/option that could do this without having to bother with a macro?

Alternatively (as I also posted in Programming community), I am open to method that could shift the column values into the matrix, if there is one that isn't too dangerously complicated.

Also alternatively, I might be open to getting a full matrix of Yule's Y instead of the tetrachoric correlations, if anyone knows how to do that and it is easier.

Thanks!

Re: Output full matrix of tetrachoric correlations

Reeza — Tue, 20 Sep 2022 18:34:00 GMT

Not aware of an option/procedure. You basically need to do the data manipulation.


data tcorr2;
	set tcorr;
	by var;
	output;
	t_var=withVar;
	withVar=var;
	var=t_var;
	output;
	drop t_var;
run;

proc sort data=tcorr2;
	by var withVar;
run;

data tcorr3;
	set tcorr2;
	by var;
	output;

	if first.var then
		do;
			withVar=var;
			corr=1;
			output;
		end;
run;

proc sort data=tcorr3;
	by var withVar;
run;

proc transpose data=tcorr3 out=want;
	by var;
	id withVar;
	var corr;
run;

Re: Output full matrix of tetrachoric correlations

StatDave — Tue, 20 Sep 2022 18:47:59 GMT

When you are looking for a particular statistic in SAS, check the list of Frequently Asked-for Statistics (FASTats) in the Important Links section of the Statistical Procedures Community page. As noted there in the "Tetrachoric correlation matrix" and "Correlations" items, you can use the OUTPLC= option in PROC CORR.

Re: Output full matrix of tetrachoric correlations

awesome_opossum — Tue, 20 Sep 2022 18:53:34 GMT

Always the best, Reeza. Thank you!

Re: Output full matrix of tetrachoric correlations

Ksharp — Wed, 21 Sep 2022 11:51:42 GMT

/*It is a SAS/IML thing*/
data have;
   input var $ withvar $ corr;
datalines;
var1 var2  0.096
var1 var3  -0.062
var1 var4  0.097
var2 var3  -0.413
var2 var4  -0.0037
var3 var4  0.074
;

proc iml;
use have;
read all var{var withvar corr};
close;
x=corr||num(compress(var,,'kd'))||num(compress(withvar,,'kd'));
f=full(x);
n=ncol(f);
w=f//j(1,n,0);
want=w+t(w)+i(n);
vname='var1':'var'+char(n);
create want from want[c=vname r=vname ];
append from want[r=vname];
close;
quit;