This solution such as " data<-na.omit(original database) before you run step() or stepAIC()" has some limitations, I think. I reduced the number of data lines, and it enhance R square value.
If you have some tips or advices for another solution, I welcome. Kum Urban and Regional Planning, GRI On Sat, Feb 20, 2010 at 5:57 AM, Greg Snow <greg.s...@imail.org> wrote: > Have you considered the implications of that solution? > > -- > Gregory (Greg) L. Snow Ph.D. > Statistical Data Center > Intermountain Healthcare > greg.s...@imail.org > 801.408.8111 > > >> -----Original Message----- >> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r- >> project.org] On Behalf Of Kum-Hoe Hwang >> Sent: Wednesday, February 17, 2010 1:41 AM >> To: r-help@r-project.org >> Subject: Re: [R] Error of Stepwise Regression with number of rows in >> use has changed: remove missing values? >> >> I thank those who helped to solve a error in stepwise regression with >> missing values. >> >> >> Kum >> >> * >> * >> >> A good solution that I have tried was Andreas's advice. >> >> ===================================================================== >> >> Try >> >> data<-na.omit(original database) before you run step() or stepAIC() >> >> On Tue, Feb 16, 2010 at 8:09 PM, Peter Ehlers <ehl...@ucalgary.ca> >> wrote: >> >> > On 2010-02-16 1:24, Kum-Hoe Hwang wrote: >> > >> >> Howdy, R Grues >> >> >> >> I have enjoyed R, but I cannot solve one problem easily. Please help >> my >> >> problem. >> >> When I tried the R script, I got the following Error. This error >> >> results from input data file exported through a Excel spreadsheet >> >> software. >> >> >> >> Error in step(lm(pop.rate ~ as.numeric(year) + as.factor(policy) + >> >> as.numeric(nation.grant) + : >> >> number of rows in use has changed: remove missing values? >> >> >> >> Could you direct me to solve the Error? >> >> Thanks in advance, >> >> >> > >> > This is a common situation when you use step() on data where >> > the predictors have missing values. >> > >> > A case (row) is included in the model only if all the >> > predictors for that model are non-missing for the case. >> > >> > As you vary which predictors are to be in the model, the >> > included cases will vary, resulting in models based on >> > different data. (Think of your cases as subjects; you want >> > all your models to be based on the same set of subjects.) >> > >> > Finally: (Re-)read the help page and note the 'warning'. >> > >> > -Peter Ehlers >> > >> > >> > >> >> >> >> ############### outputs from R console ############### >> >>> pop<- step( >> >>> >> >> + lm(pop.rate ~ as.numeric(year) + as.factor(policy) + >> >> as.numeric(nation.grant) >> >> + + as.numeric(do.grant) + as.numeric(city.grant) + >> >> as.numeric(DMZ.dist) + as.numeric(Seoul.dist), data=borderI.data, >> >> na.action = na.omit) >> >> + ) >> >> Start: AIC=494.27 >> >> pop.rate ~ as.numeric(year) + as.factor(policy) + >> as.numeric(nation.grant) >> >> + >> >> as.numeric(do.grant) + as.numeric(city.grant) + >> as.numeric(DMZ.dist) + >> >> as.numeric(Seoul.dist) >> >> Df Sum of Sq RSS AIC >> >> - as.numeric(do.grant) 1 0.71 6622.9 492.28 >> >> - as.factor(policy) 1 1.21 6623.4 492.29 >> >> - as.numeric(DMZ.dist) 1 1.91 6624.1 492.30 >> >> - as.numeric(city.grant) 1 5.07 6627.3 492.36 >> >> - as.numeric(nation.grant) 1 11.51 6633.7 492.47 >> >> - as.numeric(year) 1 29.58 6651.8 492.80 >> >> <none> 6622.2 494.27 >> >> - as.numeric(Seoul.dist) 1 673.22 7295.4 503.79 >> >> Step: AIC=492.28 >> >> pop.rate ~ as.numeric(year) + as.factor(policy) + >> as.numeric(nation.grant) >> >> + >> >> as.numeric(city.grant) + as.numeric(DMZ.dist) + >> as.numeric(Seoul.dist) >> >> Df Sum of Sq RSS AIC >> >> - as.factor(policy) 1 1.99 6624.9 490.32 >> >> - as.numeric(DMZ.dist) 1 2.09 6625.0 490.32 >> >> - as.numeric(city.grant) 1 7.18 6630.1 490.41 >> >> - as.numeric(nation.grant) 1 20.08 6643.0 490.64 >> >> - as.numeric(year) 1 28.89 6651.8 490.80 >> >> <none> 6622.9 492.28 >> >> - as.numeric(Seoul.dist) 1 697.46 7320.4 502.20 >> >> Step: AIC=490.32 >> >> pop.rate ~ as.numeric(year) + as.numeric(nation.grant) + >> >> as.numeric(city.grant) + >> >> as.numeric(DMZ.dist) + as.numeric(Seoul.dist) >> >> Df Sum of Sq RSS AIC >> >> - as.numeric(DMZ.dist) 1 2.08 6627.0 488.35 >> >> - as.numeric(city.grant) 1 10.65 6635.6 488.51 >> >> - as.numeric(nation.grant) 1 31.30 6656.2 488.88 >> >> - as.numeric(year) 1 31.44 6656.4 488.88 >> >> <none> 6624.9 490.32 >> >> - as.numeric(Seoul.dist) 1 732.88 7357.8 500.80 >> >> Step: AIC=488.35 >> >> pop.rate ~ as.numeric(year) + as.numeric(nation.grant) + >> >> as.numeric(city.grant) + >> >> as.numeric(Seoul.dist) >> >> Df Sum of Sq RSS AIC >> >> - as.numeric(city.grant) 1 9.86 6636.9 486.53 >> >> - as.numeric(year) 1 31.42 6658.4 486.92 >> >> - as.numeric(nation.grant) 1 33.33 6660.3 486.95 >> >> <none> 6627.0 488.35 >> >> - as.numeric(Seoul.dist) 1 754.40 7381.4 499.18 >> >> >> >> Error in step(lm(pop.rate ~ as.numeric(year) + as.factor(policy) + >> >> as.numeric(nation.grant) + : >> >> >> >> -------------------------------------------------------------------- >> ----------------------------------------------------------------------- >> >> number of rows in use has changed: remove missing values? >> >> >> >> -------------------------------------------------------------------- >> ---------------------- >> >> >> >> >> >> >> >> >> >> -- >> >> Kum-Hoe Hwang, Ph.D. >> >> >> >> Phone : 82-31-250-3516 >> >> Email : phdhw...@gmail.com >> >> >> >> >> > -- >> > Peter Ehlers >> > University of Calgary >> > >> >> >> >> -- >> Kum-Hoe Hwang, Ph.D. >> >> Phone : 82-31-250-3516 >> Email : phdhw...@gmail.com >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@r-project.org 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. > -- Kum-Hoe Hwang, Ph.D. Phone : 82-31-250-3516 Email : phdhw...@gmail.com ______________________________________________ R-help@r-project.org 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.
