st: How to save cell values in the tabulate twoway output?

[Bo Rud <mail@borud.dk>]

I have a problem with the handling of data resulting from a dichotomous 
test performed by 53 observers in 102 patients.
My data set consists of the 53 observers' assessments as well as the 
true diagnosis in the coloumns (variables).
The data set has 102 rows corresponding to the number of patients 
assessed by each of the observers.

patient  obs1  obs2 ... obs53  diagnose
1
2
..
102

I use the following commands to generate 2x2 tables with numbers of 
true-positive(tp), false-positive(fp), false-negative(fn) and
true-negative(tn) test outcomes for each observer:

forvalues i = 1/53 {
tab obs`i' diagnose
}

I would like to save the cell values in the tab output for further 
analysis, but I can't find a way to do it.
My ambition is to generate a new data set with the following structure:

Obs tp fp fn tn
1
2
..
53

I'm aware of the matcell-option with tab, but the programing it entails 
appears beyond my level of expertise.
Is there an easier way around?

Bo Rud
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