I have thoughts on various levels. Others
can advise better on survey statistics, the quantum
mechanics of statistics, in which thinking you
understand probably means you are not confused
at a high enough level.
1. I see that you are using -cumul- with -aweight- and
-xtile- with -pweight- and I would have thought it quite
likely that that would be a source of difficulty.
I know that -cumul- doesn't support -pweight-,
but ignoring that problem won't be a solution.
-cumul- itself is not a big deal; so as long
as you can define the cumulative for a set
of values with associated pweights, its
computation should be easy, using -sum()-
to cumulate.
2. You reported problems with -xtile2-.
Please say where user-written programs you
are using come from. -xtile2- is a user-written
program from SSC. It gives you the error
you report, I surmise, because it lacks
a -version- statement and so is broken
by a later change in Stata's syntax. This
issue was discussed at length in a recent
thread on -outreg2-. I think you need
to insert
version 7
after the -program- statement.
3. I think that the term "cumulative
distribution function" is more nearly
standard. I know that a density function
is integrated to get a distribution
function, but the result is no longer
a density. Anyway, literatures may differ,
but my impression is that cumulative
density is not a standard term.
4. Code like
gen quint=1 if cumdens<=.2
replace quint=2 if cumdens>.2&cumdens<=.4
replace quint=3 if cumdens>.4&cumdens<=.6
replace quint=4 if cumdens>.6&cumdens<=.8
replace quint=5 if cumdens>.8&cumdens~=.
could be condensed to this
gen quint = ceil(5 * cumdens)
Here -ceil()- short for "ceiling"
rounds up to the nearest integer. Also
there is need to trap missings.
-ceil()- is discussed in
SJ-3-4 dm0002 . . . . . . . . Stata tip 2: Building with floors and ceilings
Q4/03 SJ 3(4):446--447 (no commands)
tips for using floor() and ceil()
and again in "33 Stata Tips" available
from StataCorp in paperback.
Nick
[email protected]
Anna Gueorguieva
> My quintiles and poverty status do not seem to be in sync and
> I have no idea what is going on!!
>
> I generate my indicator for poor as having consumption per
> adult equivalent below the poverty line.
> gen poor=real_totc_per_ae<=povline_m
>
> Then I generate my quintiles by creating a cumulative
> distribution of consumption (in each survey wave)
> I use xtile and then double check it with the cumulative density.
>
> foreach x of numlist 1/4{
> xtile quint`x'= real_totc_per_ae [pw=postpweight] if wave==`x',nq(5)
> }
> gen quint=quint1
> foreach x of numlist 1/4{
> replace quint=quint`x' if wave==`x'
> }
>
> bys wave: cumul real_totc [aweight=postpweight], gen(cumdens)
>
> *check quints
> replace quint=1 if cumdens<=.2
> replace quint=2 if cumdens>.2&cumdens<=.4
> replace quint=3 if cumdens>.4&cumdens<=.6
> replace quint=4 if cumdens>.6&cumdens<=.8
> replace quint=5 if cumdens>.8&cumdens~=.
> And the problem is below -- it is not possible that there are
> poor people in quintile 3!!!! :
> tab quint poor [aw=postpweight] if wave==2, col nof
> Quintile |
> of |
> national |
> distributi | poor
> on | 0 1 | Total
> -----------+----------------------+----------
> 1 | 0.00 45.96 | 19.98
> 2 | 0.40 45.44 | 19.98
> 3 | 28.81 8.61 | 20.03
> 4 | 35.19 0.00 | 19.89
> 5 | 35.60 0.00 | 20.12
> -----------+----------------------+----------
> Total | 100.00 100.00 | 100.00
>
> And xtile2 gives me an error:
> xtile2 newquint=real_totc_per_ae [pw=postpweight] ,nq(5) by(wave)
> program error: matching close brace not found
> r(198);
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