"Year is not regularly spaced" r(198)

[Flynn Davies]

Hi All,

I am analysing unbalanced panel data with firm fundamental information by year over the period 1987 - 2023. Naturally firms IPO at later dates or cease trading at various stages over this period.

I am running the following code;

logit DivPayer idiosyncratic_volatility M2B Asset_Growth Profitability SIZE

estimates store logit_model
estimates table logit_model, eform
xtset gvkey stata_date

newey DivPayer Legislation_Dummy idiosyncratic_volatility M2B Asset_Growth sqrt_profitability SIZE, lag(2)

However I get a

"year is not regularly spaced
r(198);"

error when attempting to run the code. Any idea how to resolve this issue?

Cheers,
Flynn