understanding difficulties

[Faruque Sunny]

Hello,
I am a new STATA user and I have tried to anyalyze my data using fixed effect (within) IV regression.

xtivreg yieldkg age edu experience (soiltest = information),fe
here,
yieldkg is my dependent variable

soiltest is treatment variable and information is IV.

But after seeing the results, I am unable to figure out why the value of “age, edu and experience" is zero.

I will be really grateful if anyone kindly explain to me about this problem.

Thank you very much in advance.

Sincerely,
Faruque.

[Carlo Lazzaro]

Faruque:
the explanation rests on the -fe- machinery, no matter the instrumental variable approach.
As reported in any decent panel data econometrics textbook, -fe- estimator gets rid of time-invariant predictors. If age, education and experience do not vary across the data waves, Stata returns exactly what should be expected.

[Faruque Sunny]

Dear Carlo,
Thank you very much for your reply. Do you think its better to remove these variables from regression?
Thanks in advance.

Sincerely,
Faruque.

[Carlo Lazzaro]

Faruque:
not quite.
The right approach is to investigate via -hausman- which specification (-fe- or -re-) fits your data better.

[Faruque Sunny]

Thank you so much Carlo.

[Faruque Sunny]

Hello Mr. Carlo,

I am trying to run DID regression to find out the impact of a decision support tool on farmers yield productivity.

I have total sample of 168 farmers which is divided into 2 farmers group (group A and B), each group conatins 84 farmers. In Group A, 42 farmers are from region "a" and other 42 from region 'b". For Group B the farmers and their regions segmented similarly. The data set also contains before (2016) and after (2017) condition of the respondents.

In 2016 none of the farmers from Group A and B used this facility. But In 2017 "Group A" farmers have adopted but "Group B" farmers did not.

I kindly request you to please suggest me how to create treatment and control condition for this study.

Thank you very much in advance.

Sincerely,
Faruque

[Eric de Souza]

Differences-in-Differences (using Stata)

https://dss.princeton.edu/training/DID101.pdf

[Faruque Sunny]

Thank you so much Eric.