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From |
John Ataguba <johnataguba@yahoo.co.uk> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: R: RE: Imputing values for an Index |

Date |
Mon, 22 Sep 2008 08:53:04 +0000 (GMT) |

Hi Nick & Carlo, Thanks for the response. I will have a good look at the useful suggestions. Rergards Jon ----- Original Message ---- From: Carlo Lazzaro <carlo.lazzaro@tin.it> To: statalist@hsphsun2.harvard.edu Sent: Wednesday, 17 September, 2008 7:11:23 Subject: st: R: RE: Imputing values for an Index Dear John and Nick, hoping to point out a useful reference on dealing with missing data (continuous variables, namely), please find below the following one (I have found it really useful in the recent past): Briggs A, Clark T, Wolstenholme J and Clarke P. Missing....presumed at random: cost-analysis of incomplete data. Health Economics 2003; 12: 377–392 Kind Regards, Carlo -----Messaggio originale----- Da: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di Nick Cox Inviato: mercoledì 17 settembre 2008 15.09 A: statalist@hsphsun2.harvard.edu Oggetto: st: RE: Imputing values for an Index This raises questions on several levels. I am queasy at your tactic of finding a reference that supports what you intend to do. I don't think the alternative of saying that you can't do this if you have missing values is that outrageous, but I don't know your context. All methods of dealing with missing data other than going out and measuring again -- when that is possible -- are deeply unsatisfactory, but some are more deeply unsatisfactory than others. There definitely are different takes but 1. I would impute upstream, and then do -pca-. If you do -pca- and then impute, your interpretation problems seem even greater. 2. I would always compare results for complete observations and for complete plus imputed to see what differences there are. You gain from knowing how bad the problem is, 3. -impute- is among the lousiest ways to do this. -ice- (use -findit-) is generally considered much better, it seems. I've never use it.... Nick n.j.cox@durham.ac.uk John Ataguba I am implementing the -pca- command to generate an index of socioeconomic status. Stata will not provide values for any observation that is missing in any variable when you use the -predict, score- after the -pca- command. I decided to use the -impute- command to fill in the missing values of the index. Noting particularly that the missing values are not much and could be assumed to be random. My problem is that I need a valid reference to backup the process or to see if there is a more neater way to get around this. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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