[R] Print out progress reports of add1()

[Duncan Murdoch]

You are using add1 on an "lm" object, and add1.lm doesn't have a trace 
parameter.

Duncan Murdoch

On 18/01/2021 10:55 a.m., Chao Liu wrote:
> I have a few questions about using add1(). First of all, according to the R
> document of add1(), the trace = TRUE function prints out progress reports
> but my attempts to do this have failed several times. So how do we print
> out the progress reports of adding terms to the model so as to test for
> improved fit (or not)? Also, why the LRT (likelihood-ratio test) value is
> not in the output? Any help is greatly appreciated! Example as follows:
> 
> require(graphics); require(utils)
> lm1 <- lm(Fertility ~ ., data = swiss)
> add1(lm1, scope = .~. + .^2, test="Chisq", trace = TRUE)
> 
> #It seems that no progress report has been printed. Also `LRT` is missing
> Single term additions
> 
> Model:
> Fertility ~ Agriculture + Examination + Education + Catholic +
>      Infant.Mortality
>                               Df Sum of Sq  RSS AIC Pr(>Chi)
> <none>                                    2105 191
> Agriculture:Examination       1      10.7 2094 192   0.6251
> Agriculture:Education         1       1.8 2103 193   0.8399
> Agriculture:Catholic          1      75.0 2030 191   0.1915
> Agriculture:Infant.Mortality  1       4.4 2101 193   0.7528
> Examination:Education         1      48.7 2056 192   0.2943
> Examination:Catholic          1      40.8 2064 192   0.3378
> Examination:Infant.Mortality  1      65.9 2039 191   0.2216
> Education:Catholic            1     278.2 1827 186   0.0099 **
> Education:Infant.Mortality    1      93.0 2012 191   0.1451
> Catholic:Infant.Mortality     1       2.4 2103 193   0.8184
> ---
> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> 
> Best,
> 
> Chao
> 
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