Hi, I am new here and fairly new to stata and all of statistics. As I am currently writing my master thesis, I have to use stata to analyze a conducted field experiment. During the experiment, I implemented a treatment in one treatment group and had one control group to account for the difference. Now I have a panel data set consisting of 137 individuums divided up into 2 groups and have four entries for four different time stamps (in my case I tracked performance in one task on a monthly basis meaning that I have the performance of each individuum in that task over a time horizon of 4 months).
I used xtset ID Month for setting up my panel data in stata (ID is describes all 147 individuums and Month goes from 1 to 4 for the four months)
I then used the xtdidregress functions for panel data with fixed effects. To use that function I created a dummy variable for all observations that occurred in month 4 (because that's when the treatment was implemented) and that was part of the treatment group. Meaning all observations that were treated and that occurred in month 4 are assigned with a one, and all other observations are assigned with a 0.
I then ran the command:
xtdidregres (Invoicing) (Treated Dummy), group(TreatmentGroup) time(Month)
With Invoicing being the name of the variable that I tried to affect with my treatment, TreatedDummy being the described dummy variable for all observations in month 4 that were treated and TreatmentGroup being the variable that describes whether the observation was part of the control group (=1) or the treatment group (=2). Month is my time variable that has values between 1 and 4.
I then tried to run a granger test with:
estat granger
The result I got is;
Granger causality test
H0: No effect in anticipation of treatment
F(0, 1) = .
Prob > F = .
Can anybody explain what this is supposed to mean? Why do I not get any results but no error code? I get the same result when I try doing parallel trend analysis with estat ptrends.
from what I have I have written here, can anybody tell if my dif-in-dif command is wrong so that the test can not be done? The estat trendplots command worked without any problems and looks correct.
Thank you for any help!
Cheers
Felix
I used xtset ID Month for setting up my panel data in stata (ID is describes all 147 individuums and Month goes from 1 to 4 for the four months)
I then used the xtdidregress functions for panel data with fixed effects. To use that function I created a dummy variable for all observations that occurred in month 4 (because that's when the treatment was implemented) and that was part of the treatment group. Meaning all observations that were treated and that occurred in month 4 are assigned with a one, and all other observations are assigned with a 0.
I then ran the command:
xtdidregres (Invoicing) (Treated Dummy), group(TreatmentGroup) time(Month)
With Invoicing being the name of the variable that I tried to affect with my treatment, TreatedDummy being the described dummy variable for all observations in month 4 that were treated and TreatmentGroup being the variable that describes whether the observation was part of the control group (=1) or the treatment group (=2). Month is my time variable that has values between 1 and 4.
I then tried to run a granger test with:
estat granger
The result I got is;
Granger causality test
H0: No effect in anticipation of treatment
F(0, 1) = .
Prob > F = .
Can anybody explain what this is supposed to mean? Why do I not get any results but no error code? I get the same result when I try doing parallel trend analysis with estat ptrends.
from what I have I have written here, can anybody tell if my dif-in-dif command is wrong so that the test can not be done? The estat trendplots command worked without any problems and looks correct.
Thank you for any help!
Cheers
Felix
