1) How to determine the q-order polynomials: The software allows one to specify between 0-3. Since I am mostly interested in cross-section shifts, setting it to 0 is not an option. But how would I determine to which order I'd set them to? Also: in the Honacker and King (2006) article on missing values LOESS or spline basis functions are recommended. Does Amelia II offer insights about these two techniques as well?

2) How to set the case prior efficiently: I have 135 developing countries in my data and would like to use a case prior to identify existing similarities/differences between countries. Theoretically it makes sense to group the countries by region/sub-region in terms of their similarity. Is it possible to identify countries' similarities by regions/sub-regions rather than making pairwise assessments? Also: the above-mentioned Honacker and King (2006) article talks about observational priors but does not discuss the advantages/drawbacks of case priors. Could you help me out here?