Also, and possibly more constructively, when you get an error like
> CI.c = predict(mod2, data.frame( `plant-density` = x), interval =
'c') # fail
Error in eval(predvars, data, env) : object 'plant-density' not found
you should check your assumptions. Does "newdata" actually contain a
columnn called "plant-density":
> head(data.frame( `plant-density` = x))
plant.density
1 65.00000
2 65.11912
3 65.23824
4 65.35736
5 65.47648
6 65.59560>
I.e., it doesn't. So check help for data.frame and looking for something
with names.
> On 1 Dec 2023, at 01:47 , Bert Gunter <bgunter.4567 at gmail.com>
wrote:
>
> "Thank you Rui. I didn't know about the check.names = FALSE
argument.
>> Another good reminder to always read help, but I'm not sure I
understood
>> what help to read in this case"
>
> ?data.frame , of course, which says:
>
> "check.names
>
> logical. If TRUE then the names of the variables in the data frame are
> checked to ensure that they are syntactically valid variable names and
> are not duplicated. If necessary they are adjusted (by make.names) so
> that they are. "
>
> -- Bert
>
> ______________________________________________
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--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com