data extro;
input i1-i10;
array items i1-i10;
do over items;
if items eq . then delete;
end;
if _N_ le 101;
cards;
4	5	5	5	5	5	5	4	4	4
3	5	4	3	5	5	4	3	4	3
2	3	4	3	4	4	4	3	2	4
1	4	2	1	2	4	3	1	1	1
4	5	3	4	1	5	5	3	5	3
3	3	4	3	1	3	3	2	4	3
4	2	3	3	3	3	2	4	4	2
2	4	4	4	4	4	3	2	2	2
1	2	3	2	2	3	1	2	2	2
3	2	4	3	4	2	4	2	4	2
4	5	5	5	5	5	5	4	5	4
3	5	3	4	3	4	4	4	4	1
5	4	4	4	4	4	4	3	5	2
4	5	4	4	5	5	3	5	5	4
2	2	4	2	3	4	2	2	4	2
2	1	2	3	3	2	3	1	2	1
4	2	4	2	4	5	2	1	2	2
2	5	5	4	3	4	5	1	1	4
1	3	5	5	5	5	5	3	5	5
3	5	3	3	3	5	2	3	3	3
2	1	4	2	4	4	2	2	2	2
3	4	4	4	4	5	4	3	3	4
3	3	4	3	5	4	3	3	3	3
3	4	4	3	3	4	4	2	3	3
4	5	4	3	5	5	5	2	5	2
1	5	4	3	4	5	2	4	4	1
2	3	3	3	3	3	2	2	2	1
2	3	2	3	3	3	2	2	2	3
3	5	4	3	4	5	3	1	2	4
3	4	4	3	4	4	2	2	2	2
4	5	4	4	4	4	2	3	3	4
4	5	4	4	5	4	4	2	3	2
2	2	3	2	2	2	2	2	3	2
3	4	4	4	3	4	3	2	3	2
3	4	4	4	4	5	3	3	4	4
1	4	4	4	4	5	2	2	3	2
3	3	4	4	4	4	3	4	5	4
3	4	3	2	1	3	3	3	3	1
2	3	3	2	4	3	4	3	2	4
4	4	3	4	4	3	4	2	4	2
4	4	5	4	5	4	4	3	4	4
4	4	3	4	5	4	4	4	5	3
4	5	4	5	2	2	3	4	5	3
3	5	4	3	5	5	4	3	4	3
1	4	2	3	5	3	2	4	2	4
3	5	5	5	5	5	5	1	4	4
3	2	4	4	5	5	2	4	5	4
4	5	4	4	4	5	4	3	5	3
4	5	4	4	5	5	5	1	.	1
3	3	4	3	4	2	4	3	4	3
3	4	2	3	3	3	3	2	2	3
4	4	5	4	4	5	4	3	4	4
4	5	4	4	4	4	1	2	2	2
3	5	5	4	5	4	3	2	3	2
3	4	4	3	3	4	3	1	4	3
4	5	4	5	4	5	4	3	3	5
4	5	4	5	4	5	5	5	5	4
3	5	5	5	5	4	5	2	4	3
4	5	5	4	4	4	5	3	4	4
3	3	4	3	3	4	2	2	3	2
2	3	4	3	4	4	4	1	1	4
1	1	3	2	3	1	2	3	2	2
3	4	5	3	4	5	5	4	2	2
4	5	5	4	5	5	5	3	5	4
4	5	5	5	5	4	5	4	5	5
5	5	5	5	5	4	5	5	5	3
3	4	4	4	4	5	3	2	4	4
5	5	4	4	4	5	4	3	5	5
4	5	5	5	4	5	4	5	5	4
4	5	5	5	5	5	5	2	5	5
1	3	3	2	2	4	1	2	1	1
4	5	2	5	5	5	1	5	5	2
1	3	2	1	4	5	1	3	4	3
3	4	4	3	3	4	3	3	4	3
3	4	5	4	4	5	5	2	4	3
5	3	3	5	4	5	4	3	5	4
5	5	1	4	5	5	5	4	5	5
1	2	1	1	1	1	1	1	1	1
2	3	4	3	5	3	4	2	3	3
2	2	4	2	4	4	3	2	2	3
1	1	3	2	2	2	2	1	1	1
3	2	4	3	3	3	3	2	3	2
3	2	3	3	2	3	2	2	2	2
4	5	4	5	4	5	4	4	4	4
4	5	5	5	5	5	4	4	5	4
3	5	4	5	5	5	4	3	5	4
2	4	4	2	4	4	2	2	2	2
4	4	5	4	4	4	4	3	4	4
3	2	3	2	3	4	3	2	4	2
2	5	3	4	2	5	2	3	4	1
3	2	2	2	2	4	2	1	3	1
2	3	5	4	3	3	2	2	4	2
3	5	5	5	4	5	4	1	3	2
5	5	5	5	5	5	5	1	5	1
3	2	3	2	4	3	3	2	4	3
4	4	5	4	5	5	5	2	4	5
1	4	5	3	5	5	5	1	3	2
3	2	3	2	4	4	2	2	3	2
4	2	1	2	2	2	1	1	3	1
2	4	4	3	4	5	3	3	3	4
1	3	4	5	2	2	2	4	4	2
3	2	4	3	3	2	3	3	4	2
3	2	2	1	1	2	4	1	1	1
2	2	3	2	3	4	2	2	2	2
1	4	4	2	4	1	1	1	2	1
3	4	4	4	4	4	4	3	3	3
2	4	4	3	4	4	3	2	3	2
4	4	5	4	5	5	5	3	4	3
4	4	4	4	4	4	4	3	4	4
2	3	3	4	3	3	4	2	2	2
1	4	4	1	4	4	3	2	1	3
5	5	4	5	5	5	5	4	4	5
4	3	2	3	3	4	3	1	2	1
3	2	4	3	1	3	2	1	2	1
2	3	3	5	4	3	3	4	3	4
3	5	4	4	5	4	3	4	4	4
1	4	2	4	2	3	2	2	2	2
1	1	3	1	3	3	1	1	1	1
4	5	4	5	4	5	3	4	5	4
4	5	4	5	5	4	4	4	5	5
3	4	5	5	1	1	4	1	1	5
3	4	4	4	4	4	3	3	4	1
1	2	2	2	2	3	1	5	2	2
4	5	1	2	3	4	1	1	1	1
3	5	4	3	4	5	3	3	4	1
3	2	4	3	2	2	2	2	3	2
3	5	4	4	4	5	3	2	3	3
4	5	4	5	5	5	3	4	5	3
4	5	5	4	4	5	4	3	4	3
3	2	4	3	3	3	3	3	3	2
4	5	4	4	4	3	4	3	4	3
3	4	5	5	5	5	4	4	5	2
4	4	4	4	4	4	3	4	5	2
3	3	4	3	3	4	4	3	3	3
4	5	1	5	5	5	5	5	5	5
3	3	3	3	3	4	3	3	4	2
2	4	2	3	2	3	4	5	4	4
4	4	4	4	3	4	4	4	5	2
3	4	4	4	3	3	3	3	3	2
4	4	4	2	2	4	2	3	4	1
4	5	4	4	3	3	2	3	2	2
2	3	2	1	2	4	2	4	2	1
3	3	3	3	3	3	3	2	2	3
5	3	4	4	3	5	2	4	5	4
5	5	4	1	4	5	4	5	5	1
2	4	3	4	3	4	2	4	2	4
1	3	4	1	4	1	5	1	1	1
1	4	2	2	2	2	1	4	2	1
4	5	5	4	5	4	5	4	5	4
3	3	3	4	2	4	5	4	3	4
2	4	3	2	4	5	2	3	2	2
4	5	3	4	4	5	3	4	4	4
3	3	3	3	4	2	3	1	4	4
3	5	3	4	4	5	3	3	4	3
3	4	4	4	4	3	2	3	4	4
3	4	4	3	4	4	2	3	4	3
1	2	3	2	2	3	1	3	3	1
4	3	4	4	3	4	4	3	4	3
4	5	5	5	5	5	5	5	5	2
4	5	5	5	5	5	5	4	5	5
3	3	3	3	4	3	3	3	3	3
3	5	4	3	4	4	3	3	4	4
4	5	5	5	5	5	5	4	5	5
3	4	4	5	4	4	5	2	3	4
2	5	5	5	5	5	4	4	4	5
4	5	5	5	5	5	5	4	5	4
1	4	2	3	2	2	2	1	1	2
3	4	4	4	4	4	4	4	5	4
2	5	5	4	5	5	2	3	5	4
4	5	5	2	5	5	5	2	5	4
3	1	2	1	4	3	1	1	2	1
1	3	2	1	2	4	1	1	1	1
1	2	1	1	1	2	1	1	1	1
3	1	4	1	2	4	1	1	5	1
3	2	4	2	4	4	4	3	3	2
2	2	2	2	2	2	2	1	2	2
3	4	2	3	4	4	3	4	4	3
3	4	4	4	4	.	.	.	.	.
4	5	5	4	5	4	5	4	4	4
3	4	5	3	5	3	3	2	3	3
2	3	5	3	3	4	3	3	4	3
3	3	4	5	3	5	2	4	5	4
3	2	3	3	2	3	3	4	4	1
4	5	4	4	5	5	5	2	4	2
4	3	4	2	4	3	4	1	3	1
4	5	4	4	4	4	5	2	3	4
1	3	2	2	2	4	3	2	1	1
4	4	5	4	5	5	4	2	4	5
5	3	4	5	1	3	3	4	5	4
1	4	3	2	2	3	1	1	1	2
2	1	1	2	2	4	1	3	4	1
1	2	3	1	1	4	1	1	1	2
2	1	3	2	1	3	1	3	2	1
3	3	3	2	3	3	2	2	3	2
3	4	4	4	4	2	4	3	3	2
1	2	3	2	2	3	1	1	1	1
4	5	4	3	4	5	4	3	4	4
proc iml;
*********************************************************************
*  The algorithm in this program is due to 
*  Iacobucci, D., & Duhachek, A. (2003).  Advancing alpha:
*   Measuring reliability with confidence.  Journal of Consumer
*   Psychology, 13, 478-487.
*********************************************************************;
use extro var{i1 i2 i3 i4 i5 i6 i7 i8 i9 i10};
**********************************************************************;
* the dataset name that you want to analyze follows the word 'use'.
* The name of the variables in the dataset are named after 'var'.
**********************************************************************;
read all var{i1 i2 i3 i4 i5 i6 i7 i8 i9 i10} into x;
*x contains the raw data - it has items as columns and people as rows;
numbitem = ncol(x); * find the number of items in the scale;
numbsubj = nrow(x); * find the number of people, the sample size;
bigone = j(numbsubj, 1);
means = ((bigone`)*x)/numbsubj;
xd = x-(bigone*means);
itemcov = (1/(numbsubj-1))*((xd`)*xd);
**************************************;
*itemcov is the item covariance matrix;
*next are the analyses;
**************************************;
one = j(numbitem,1);
jtphij = (one`)*itemcov*one;
myalpha = 1 - ((trace(itemcov))/jtphij);
myalpha = (numbitem/(numbitem-1))*myalpha;
trphisq = trace(itemcov*itemcov);
trsqphi = (trace(itemcov))**2;
jtphisqj = (one`)*(itemcov*itemcov)*one; 
omega = jtphij*(trphisq+trsqphi);
omega = omega-(2*(trace(itemcov))*jtphisqj);
omega = (2/(jtphij**3))*omega;
s2 = (numbitem**2)/((numbitem-1)**2);
s2 = s2*omega;
se = sqrt(s2/numbsubj);
cimin95 = myalpha-(1.96*se);
cimax95 = myalpha+(1.96*se);
s = diag(itemcov);
s = sqrt(s); s = s**(-1);
corrs = s`*itemcov*s;
*****************************************
*print output
*****************************************;
print 'Your covariance matrix:';
print itemcov;
print 'Your correlation matrix:';
print corrs;
print 'Your number of items and sample size:';
print numbitem numbsubj;
print 'Alpha is';
print myalpha;
print 'The lower and upper confidence interval bounds are'; 
print cimin95 cimax95;
quit;
run;