See lwuf
for more information, but I'll copy-paste it here
too.
The letter published by Carter and Smith (2020) contains more information
as to what these thetas refer. The "M1" theta is a variation of the standard
Rasch model from the boilerplate information in the LEAD data. The authors
consider this to be "theoretically relevant" or "risk-related" as these all
refer to conflict or risk-taking. The "M2" theta expands on "M1" by
including political orientation and psychological characteristics. "M3" and
"M4" expand on "M1" and "M2" by considering all 36 variables in the LEAD
data.
The authors construct and include all these measures, though their analyses
suggest "M2" is the best-performing measure. You should probably consider
using theta2_mean
as your default estimate of leader willingness
to use force in leader-year analyses.