Olena Stavrunova
> I have a panel data (id and quarters) and my categorical
> variable fcat takes 81
> values. I need to calculate transition probabilities for
> fcat and want to use
> xttrans because it produces exactly what I need. However, I get the
> message "too many values". Is there a way to make xttrans
> work for 81 values?
> I am Stata 7 user.
You are hitting some limit of -tabulate-, although
I don't know what it is. The same limit applies
in Stata 8.
Incidentally, -xttrans- calculates not transition
probabilities, but those multiplied by 100.
The following appears to produce the numbers
you want:
*! NJC 14 July 2003
*! version 1.0.7 14jan2000
program define xttrans3, rclass byable(recall) sort
version 6
syntax varname [if] [in] [, I(varname) T(varname) * ]
xt_iis `i'
local ivar "`s(ivar)'"
xt_tis `t'
local tvar "`s(timevar)'"
tempvar touse
mark `touse' `if' `in'
markout `touse' `varlist' `ivar' `tvar'
tempvar was is numer denom prob
quietly {
sort `ivar' `tvar'
by `ivar': gen float `was' = `varlist' if _n<_N
by `ivar': gen float `is' = `varlist'[_n+1] if _n<_N
local lbl : var label `varlist'
if "`lbl'"=="" {
local lbl "`varlist'"
}
label var `was' "`lbl'"
label var `is' "`lbl'"
by `ivar': replace `touse'=0 if `touse'[_n+1]==0 & _n<_N
markout `touse' `was'
markout `touse' `is'
bysort `touse' `was' (`is') : gen `denom' = _N if `touse'
by `touse' `was' `is' : gen `numer' = _N if `touse'
gen `prob' = 100 * `numer' / `denom'
}
tabdisp `was' `is' if `touse', c(`prob') `options'
ret add
end
exit
syntax is
xttrans3 fcat, <tabdisp_options>
If you want the probabilities themselves, edit
the code to remove "100 *".
Nick
[email protected]
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