Article View: sci.math.stat
Article #568modelling distributions
From: Mike Anderson
Date: Wed, 11 Nov 1992 19:47
Date: Wed, 11 Nov 1992 19:47
24 lines
2077 bytes
2077 bytes
Suppose I have data on two variables - age and income of a person. I would like to estimate income curves by age using spline regression, but my problem is this: to protect the identity of the individuals, incomes were topcoded, so that any person reporting incomes of > $100,000 gets coded at $100,000. I am interested in getting very accurate estimates, and given the long right tail of the income distribution, these truncated values may be throwing off my estimates quite a bit. So I would like to replace the truncated values with my own "tail". My question is, how do I go about modelling the income distribution and tacking on my own tail? Off the top of my head, I would precede thusly: If there are Nt truncated observations and Nu untruncated observations, N = Nt + Nu, I would first scale the Nu incomes to mean 0, generate N obs from something like a log-normal, lop off the top Nt quantiles, and compare the generated data to the observed data with a Q-Q plot, choosing that level of variance in the log-normal which gives me the straightest fit. Then I would take the Nt random values I lopped off from the generated data and randomly assign them to the Nt truncated values. Does this sound reasonable? I'm sure there is a better way to go about this, can someone tell me what it is or where to find it? Thanks in advance, Mike Anderson -- Mike Anderson Dept. of Demography UC Berkeley mwande@QAL.Berkeley.EDU "And I would say to those out around the country. 'Take a hard look now. Don't let that rabbit be pulled out of the hat by one hand and 25 other rabbits dumped on you in another.'" - George Bush, 1/24/90
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Path: arc1-ca.pugleaf.net!sparky!uunet!think.com!sdd.hp.com!spool.mu.edu!agate!graunt.qal.berkeley.edu!mwande From: mwande@graunt.qal.berkeley.edu (Mike Anderson) Newsgroups: sci.math.stat Subject: modelling distributions Date: 11 Nov 1992 19:47:23 GMT Organization: University of California, Berkeley Lines: 24 Distribution: world Message-ID: <1dro0bINN8p9@agate.berkeley.edu> NNTP-Posting-Host: graunt.qal.berkeley.edu