Dear all,

For my thesis, I need to run the following regression:

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In a paper, where I base my thesis on, it states: Instrumental variables estimation is still required because perf(it) is used to calculate both delta(perf(it+1)) and delta(perf(it)).
I used the following command to estimate this regression:

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The performance measure is OperatingIncome. The rest of the variables are slightly different from the specification above.
A part of the corresponding output is:
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As you can see, the tests are okay.
Neverhteless, I am worried about the signs: Revlag, which is the lagged version of log(total revenues) and RevGrwlag, which is the lagged version of revenue growth are negative in predicting the operating income.
I was wondering if I made a mistake in my model specification. The options were added to deal with heteroscedasticity and autocorrelation.

Thanks in advance


Thanks in advance