Dear all,
I have a panel data set with economic and political variables for
country-years. I want to estimate 2 slightly different models and compare
the results. One Model includes Var1 and some controls, the second includes
a break-down of Var1 into its components, and the same (!) controls. I
claim that Var1 can better explain the outcome when broken down into its
components. More concretely, I compare the effects of total FDI with
effects of FDI broken down into business sectors.
Model 1 is:
Y = Var1 + Controls
Model 2 is:
Y = Var1a + Var1b + Var1c + Controls
Ideally I would run an imputation that includes all variables (in model 1
and 2), and then estimate the models. However, my problem is: For Model 2 I
have very bad data availability for a bulk of country-years in Var1a,
Var1b, Var1c.
Solution 1: I could kick out country-years with >80% missingness from the
complete panel data set and run one overall imputation. I would then
estimate Model 1 and 2 with the same imputed data set(s) and the estimates
would remain comparable. However, this means that Model 1 would be
estimated with less country-years than originally possible, just because I
want to compare it with Model 2 which has high missingness in its
variables.
Solution 2: I am also thinking of building subsets of my master table to
run 2 separate imputations. Subset 1 for Model 1 would include all years
and countries - but not Var1a + Var1b + Var1c from model 2. Subest 2 for
Model 2 would include all variables; but I would cut out 5 years and 20
countries which have >80% missingness. Var1a + Var1b + Var1c would
obviously remain in the subset. I am hesitating because there is an overlap
in the variables in the two models (controls are the same, Var1 is broken
down into its components), and I want to compare the results.
What do you think conceptually and from the imputation point of view about
the trade-off between comparability and preservation of data points for
Model 1?
Thank you very much in advance!
Best,
Nicole
-
Nicole Janz
Doctoral Researcher
University of Cambridge
Politics and International Studies
www.nicolejanz.de | nj248(a)cam.ac.uk | +44 (0) 7905 70 1 69 4
Skype: nicole.janz