[R] (g)lm ordinal or scaled values?

[Knut Krueger]

Liaw, Andy schrieb:

>Ordinal variables should be stored as ordered factors in R.  See ?ordered.
>
thnk`s for your reply. I tried to store as ordered factors
var <- as.ordered(var2)
but if I am calling the lm(dependent~var) I get a long list of values.
If I call
var <- as.numeric(var2)
lm(dependent~var)

then I get:

Residuals:
     Min       1Q   Median       3Q      Max
-0.93563  0.01378  0.16272  0.25546  0.57862

Coefficients:
            Estimate Std. Error t value Pr(>|t|)   
(Intercept)  1.79513    0.02787  64.412  < 2e-16 ***
mean        -0.28102    0.05993  -4.689 4.66e-06 ***

the SPSS call and Result  is:

SPSS (13)
    Analyse
        General Linear Model
                Univariate
Dependent Variable -> Dependent
Fixed Factors       -> var2

OK
           



Tests of Between-Subjects Effects
Dependent Variable: dependent
 | --------------- | ------------------------- | --- | ------------- | 
-------- | ---- |
 | Source             | Type III Sum of Squares | df  | Mean Square | F 
         | Sig. |
 | --------------- | ------------------------- | --- | ------------- | 
-------- | ---- |
 | Corrected Model | 11,269(a)                   | 41  | ,275           
  | 1,668    | ,012 |
 | --------------- | ------------------------- | --- | ------------- | 
-------- | ---- |
 | Intercept       | 361,340                 | 1   | 361,340     | 
2193,088 | ,000 |
 | --------------- | ----------------------- | --- | ----------- | 
-------- | ---- |
 | var2            | 11,269                  | 41  | ,275        | 
1,668    | ,012 |
 | --------------- | ----------------------- | --- | ----------- | 
-------- | ---- |
 | Error           | 31,964                  | 194 | ,165        
|          |      |
 | --------------- | ----------------------- | --- | ----------- | 
-------- | ---- |
 | Total           | 773,000                 | 236 |             
|          |      |
 | --------------- | ----------------------- | --- | ----------- | 
-------- | ---- |
 | Corrected Total | 43,233                  | 235 |             
|          |      |
 | --------------- | ----------------------- | --- | ----------- | 
-------- | ---- |
a R Squared = ,261 (Adjusted R Squared = ,104)


Maybe anybody is able to show me the difference between SPSS and R calls 
because the P value ic complete different
The url for the Data (if anybody would like to try)

http://biostatistic.de/temp/testr.csv

Regards Knut