On 11/05/2017 9:37 AM, Tobias Christoph wrote:
Hey,
I just have trouble adding a object specific time trend with the
plm-package. I recieve the following error:
*
**"Error in model.frame.default(terms(formula, lhs = lhs, rhs = rhs,
data = data, : invalid type for the variable 'time' "*
I used the formula:
/ FE_trend<- plm(log(revenue) ~ log(supply)+ city*time,
data=R_Test_log_Neu, model="within", effect = "twoways") //
/
Do you have an idea how to fix it?
I don't know that package and you didn't supply a reproducible example,
so there are at least these two possibilities:
1. Your dataframe R_Test_log_Neu contains no column named "time".
(Remember that "Time" and "time" are different.) Fix: use the correct
column name.
2. The plm package isn't doing lookup of symbols from the formula first
in your dataframe. This would need to be fixed in the package. A
workaround might be to name the columns with unique names that won't be
found anywhere else, e.g. name your column "NeuTime" instead of "time".
Duncan Murdoch
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