Hi guys.

For my research (Master Thesis) I have two control variables on segments: one for the number of business segments and one for the number of geographic segments. Of my sample of 2318 observations, approximately 700 have missing observations for the number of geographic segments.

When I give "1" to these observations (because every firm has at least one segment) I got significant results in the direction that I expected.

Once I run the regression with the 2318-700 sample (thus the observations that do have a value on geographic segments) the coefficient decreases nearly to zero and significance is gone (t-value 0.06).

Does anyone know what I could do best here? I don't know if I can just remove a control variable because it is a control variable that is widely used in this kind of research.

FYI: I'm examining annual report' readability of US firms.