Ordinal variables should be stored as ordered factors in R. See ?ordered. Andy
From: Knut Krueger > > There is a difference in the p- value from 0.000 and 0.012 > when I am > using SPSS. > 0.000 when I am using the independent variable as scaled > 0.012 if I am using the variable as ordinal. > > The independent variable is ordinal but it seems that R is > using the variable as an scaled, because the P- Value is > computed with 4.66e-06 > > > so I am not sure which description I am misunderstanding: > SPSS;: > Covariates. Scale predictors > <javascript:popup(N2C5F1_term,N2C5F1_def);> > should be selected as covariates > <javascript:popup(N2B079_term,N2B079_def);> in the model. Within > combinations of factor levels (or cells > <javascript:popup(N2AE3F_term,N2AE3F_def);>), values of > covariates are > assumed to be linearly correlated with values of the > dependent variables. > (A variable can be treated as scale when its values represent ordered > categories with a meaningful metric, so that distance comparisons > between values are appropriate. Examples of scale variables > include age > in years and income in thousands of dollars.) > > Factors. Categorical <javascript:popup(N2AD73_term,N2AD73_def);> > predictors should be selected as factors > <javascript:popup(N2B481_term,N2B481_def);> in the model. Each level > <javascript:popup(N2B937_term,N2B937_def);> of a factor can have a > different linear effect on the value of the dependent variable.(A > variable with a discrete number of values; an ordinal or nominal > variable. Categorical variables are often used as grouping > variables or > factors.) > > The data : http://biostatistic.de/temp/testr.csv > > lm.data<-lm( dependent ~ var2,family = gaussian) > > I don't know whether anybody could explain me the difference between > SPSS and R results but if there are different results then > one of them > is wrong :-( > And I do not know which of them. > I hope I explained the problem understandable > > Regards Knut > > ______________________________________________ > R-help@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 > > ______________________________________________ R-help@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
