[R] [NB] lm problems
Matej Cepl
matej at ceplovi.cz
Tue Nov 26 21:40:14 CET 2002
Hi,
I have probably overlooked something obvious, but could anybody
help me with following, please?
Trying to make regression analysis. I have a huge dataframe with
results from National Opinion Survey on Crime and Justice
(www.abacon.com/fox/) with two variables G5 and N3 which are
imported to R as ordered factors:
> levels(noscj$G5)
[1] "Strongly agree" "Agree" "Neither"
[4] "Disagree" "Strongly disagree"
> levels(noscj$N3)
[1] "Serious problem" "Somewhat problem" "Minor problem" "Not
a problem"
>
(missing values are duly recoded as NA). When I try linear
regression I get a lot of warnings which I have not managed to
parse succesfully:
> lm(G5 ~ N3,data=noscj)
Call:
lm(formula = G5 ~ N3, data = noscj)
Coefficients:
(Intercept) N3.L N3.Q N3.C
3.38087 -0.05821 -0.15364 0.04367
Warning message:
"-" not meaningful for ordered factors in: Ops.ordered(y,
z$residuals)
> summary(lm(G5 ~ N3,data=noscj))
Call:
lm(formula = G5 ~ N3, data = noscj)
Residuals:
[1] <NA> <NA> <NA> <NA> <NA>
Levels: Strongly agree Agree Neither Disagree Strongly disagree
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 3.38087
N3.L -0.05821
N3.Q -0.15364
N3.C 0.04367
Residual standard error: NA on 980 degrees of freedom
Multiple R-Squared: NA, Adjusted R-squared: NA
F-statistic: NA on 3 and 980 DF, p-value: NA
Warning messages:
1: "-" not meaningful for ordered factors in: Ops.ordered(y,
z$residuals)
2: "^" not meaningful for ordered factors in: Ops.ordered(r, 2)
3: ">" not meaningful for factors in: Ops.factor(qs[i], -Inf)
4: "+" not meaningful for factors in: Ops.factor(qs[i],
.minus(x[hi[i]], x[lo[i]]) * (index[i] - lo[i]))
>
Could anybody tell me, what's going on, please? I have no clue
what "^", ">", etc. means.
Thanks a lot (and thanks for your patience)
Matej
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Matej Cepl, matej at ceplovi.cz,
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