My R value is a period?

[Sophie Anderberg]

Hello,

I am deeply sorry if this has been answered somewhere and I just not have found the right keywords to answer it. I am working in Stata on an assignment for school about instrumental variables. The point of this question is to use a "bad" instrumental variable. I ran the regression and it came back with a period for the R-squared value. Can anyone tell me what this means?

I've included some of the code because most people seem to use it but I'm not sure how useful it will be without the dataset (I am using data from Kathryn Graddy's research on the Fulton Fish market.

ivregress 2sls qty badweather (price = day1 day2 day3 day4)

Thank you for any help!

[Carlo Lazzaro]

Sophie:
welcome to this forum.
As per FAQ, your chances of getting helpful reply are conditional on posting what you typed and what Stata gave you back (within CODE delimiters, please). Thanks.

[Karl Tjensvoll]

Hi Sophie

One should always be careful when using R2 to evaluate wether a model is "good" or "bad", as it says nothing about the consistency of your mode. As you noticed, when using ivregress you may get missing for R2, most likely because it becomes negative. You can read in more detail here: https://www.stata.com/support/faqs/s...least-squares/ .