[R] Error of Stepwise Regression with number of rows in use has changed: remove missing values?
Kum-Hoe Hwang
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,
> ############### 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 : phdh...@gmail.com
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Mohamed Lajnef
Hi Kum,
If you look at the code step function ( by typing step in the R
console), the condition (if (length(fit$residuals) != n) ) is not
fulfilled, this explains the error!
i hope this can help
Regards
M
Kum-Hoe Hwang a écrit :
--
Mohamed Lajnef,IE
INSERM U955 eq 15
Pôle de Psychiatrie
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Mohamed...@inserm.fr
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Sec : 01 49 81 32 90
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Peter Ehlers
> 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
--
Peter Ehlers
University of Calgary
Kum-Hoe Hwang
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()
--
Kum-Hoe Hwang, Ph.D.
Phone : 82-31-250-3516
Email : phdh...@gmail.com
[[alternative HTML version deleted]]
Kum-Hoe Hwang
I thank those who helped to solve a error in stepwise regression with
missing values.
A good solution that I have tried was Andreas's advice.
=====================================================================
Try
data<-na.omit(original database) before you run step() or stepAIC()
Kum
On Tue, Feb 16, 2010 at 8:09 PM, Peter Ehlers <ehl...@ucalgary.ca> wrote:
>
Greg Snow
--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg...@imail.org
801.408.8111
> >> --------------------------------------------------------------------
Kum-Hoe Hwang
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