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R: st: q-q plots, theoretical distribution with values higher than the sample's cutoff point
From
"Lucia R.Latino" <[email protected]>
To
<[email protected]>
Subject
R: st: q-q plots, theoretical distribution with values higher than the sample's cutoff point
Date
Wed, 18 Jul 2012 19:23:10 +0200
Dear Nick,
Thanks for your answer. Here you have the details of my variable. I hope it
can be more useful to give me some feedback.
-su dec_ae, d -
--------------------------------------------------------------------
Percentiles Smallest
|---------------------------------------|
1% 838.9864 11.1115
5% 1402.251 38.77081
10% 1733.309 112.4597 Obs 11183
25% 2352.013 116.3163 Sum of Wgt. 11183
50% 3209.503 Mean 3518.48
Largest Std. Dev.
1648.996
75% 4355.16 9948.422
90% 5793.742 9952.207 Variance 2719189
95% 6790.232 9981.6 Skewness 1.017932
99% 8768.935 9992.487 Kurtosis 4.138746
------------------------------------------------------------------
Thanks,
Lucia
-----Messaggio originale-----
Da: [email protected]
[mailto:[email protected]] Per conto di Nick Cox
Inviato: mercoledì 18 luglio 2012 18:49
A: [email protected]
Oggetto: Re: st: q-q plots, theoretical distribution with values higher than
the sample's cutoff point
These programs are in package -qpfit- on SSC.
The word "problem" here is ambiguous. My bias is to guess that your data
don't follow any of these distributions very well and the graphs are telling
you that. -su dec_ae, detail- would tell us a bit more.
Nick
On Wed, Jul 18, 2012 at 5:13 PM, Lucia Latino <[email protected]>
wrote:
> I am having some problems with the q-q plots for Dagum, gb2, lognormal
> and Singh-Maddala distributions using programs written by Nick Cox.
>
> After having fit the distribution (e.g. lognfit dec_ae, svy), I run
> the command for the q-q plot (e.g. qlogn dec_ae [pweight=iwght]).
>
> I repeat the same procedure for the other distributions (Dagum, gb2
> and Singh-Maddala). All the plots show a strange behavior: in all the
> qq-plots, the points follow a strongly nonlinear patters. At the
> beginning they follow the 45 degree line, then they depart
> significantly from the 45 degree line and become flat around the value
10,000, which is the max value for dec_ae.
>
> What does it mean? Why the theoretical distribution takes value higher
> than 10,000?
>
> I hope I was clear enough. I wish I could show you the plots, but I
> understood I cannot attach them.
>
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