Um texto embutido e sem conjunto de caracteres especificado associado... Nome: n?o dispon?vel Url: https://stat.ethz.ch/pipermail/r-help/attachments/20070708/6a87c824/attachment.pl
Sure! Read this: MAXIMUM LIKELIHOOD FROM INCOMPLETE DATA VIA EM ALGORITHM Author(s): DEMPSTER AP, LAIRD NM, RUBIN DB Source: JOURNAL OF THE ROYAL STATISTICAL SOCIETY SERIES B-METHODOLOGICAL 39 (1): 1-38 1977 then read the posting guide. Simon. On Sun, 2007-07-08 at 23:20 -0300, Marcus Vinicius wrote:> Dear all, > I need to use the EM algorithm where data are missing. > Example: > x<- c(60.87, NA, 61.53, 72.20, 68.96, NA, 68.35, 68.11, NA, 71.38) > > May anyone help me? > > Thanks. > > Marcus Vinicius > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.-- Simon Blomberg, BSc (Hons), PhD, MAppStat. Lecturer and Consultant Statistician Faculty of Biological and Chemical Sciences The University of Queensland St. Lucia Queensland 4072 Australia Room 320, Goddard Building (8) T: +61 7 3365 2506 email: S.Blomberg1_at_uq.edu.au The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. - John Tukey.
On 09-Jul-07 02:20:47, Marcus Vinicius wrote:> Dear all, > I need to use the EM algorithm where data are missing. > Example: > x<- c(60.87, NA, 61.53, 72.20, 68.96, NA, 68.35, 68.11, NA, 71.38) > > May anyone help me? > > Thanks. > > Marcus ViniciusThe Dempster, Laird & Rubin reference given by Simon Blomberg is the classical account of the EM Algorithm for incomplete information, though there has been a lot more published since. However, more to the point in the present case: If the above is typical of your data, you had better state what you want to do with the data. Do you want to fit a distribution by estimating parameters? Are they observations of a "response" variable with covariates and you want to fit a linear model estimating the coefficients? Are they data from a time-series and you need to interpolate at the missing values? Etc.?? Depending on what you want to do, the way you apply the general EM Algorithm procedure may be very different; and a lot of applications are not covered by Dempster, Laird & Rubin (1977). And there may possibly be no point anyway: If all you want to do is estimate the mean of the distribution of the data, then the best procedure may simply be to ignore the missing data. Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <ted.harding at nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 09-Jul-07 Time: 09:18:56 ------------------------------ XFMail ------------------------------