Dear Statalisters,
I have two questions about matrix operations in Stata.
Suppose there is a matrix form data set like below:
A B C D
A 0 0 0 1
B 0.3 0 0 0.7
C 0.2 0.15 0.65 0
D 0.3 0.4 0 0.3
Question 1.
To compute sum of numbers of zeros for this matrix, I wrote
the following:
foreach var of varlist A-D{
count if `var' == 0
}
The result is:
1
2
3
1
Namely, numbers of zeros for each variable are vertically
shown.
One step further, I'd like to obtain total sum of numbers
of zeros (1+2+3+1=7 in this case).
Is it possible to do so?
Question 2.
To compute sum of row variances, I wrote the following:
/* sum of row variances */
loc egen sd = rsd(A-D)
loc egen v = sd^2
loc egen sumv = sum(v)
di in gr " sum of row variances" _col(38) ": " %5.3f in ye `sumv'
While no errors are shown, the result for `sumv' are not
shown, either.
# Only the title "sum of row variances : " is shown.
I don't know why this happens, thoguh I may have made some
elementary mistakes.
Is there any alternatives to compute?
Any suggestions welcome.
Thanks in advance.
K.I.
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