[R] Error of Stepwise Regression with number of rows in use has changed: remove missing values?

[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 :
> 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,
>
>
>   
>> ############### 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 : phdhwang at gmail.com
>
> ______________________________________________
> R-help at 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.
>
>   


-- 


Mohamed Lajnef,IE 
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