December 6, 2011

Lots of goals, but lots of progress!  Ask Brian about writing me a letter for a JSM travel award.

stud12an

MMSBM – I coded the single network sampler to estimate the Dirichlet hyperparameter and so far things look okay.

***Found a pretty major mistake, so I think the gammas won’t go flying off into space – hooray!***

I have 3 different networks I’m working with, which I’m going to change to 2.  More explanation below.

(1)  membership probabilities generated with c(0.05, 0.05, 0.05) lambda.  With fairly flat priors (\gamma ~ Gamma(1,1) and \xi ~ Dir(1,1,1)), we recovered these nicely and in 5000 iterations.

(2)  membership probs generated with c(0.25, 0.25, 0.25) was much more of a challenge.  For some reason, with \gamma ~ Gamma(1,1), our gamma parameters were just going off into oblivion.  I actually couldn’t tell which was going off first, the \xi or the \gammas, but a prior of Gamma (1,2) was enough to keep things on track.  Oops, spoke too soon.  It keeps things on track about 30% of the time.

**I think the solution might be to bound the gamma, but I’m sure there’s a better explanation***

(3)  I think it doesn’t really make sense to focus on networks generating with anything higher, actually.  But the third network is generated with c(0.5, 0.5, 0.5) and I anticipate the same issue with gamma and xi.    We’ll see if a Gamma(1,2) prior works on this one.

Hopefully Brian and Andrew can help me figure that out tomorrow.

HLSM – results have been put in the final paper.  It’s been proofed and now the only things I need to do are (a) proof read that last section and (b) ready it for submission!!!

And as far as paper writing is concerned, I’ve “started” the MM chapter, but I have a ways to go.  I am going to write the paper in more detail later this week…but I’m having a hard time jumping in to write when I don’t actually have results yet.  But now that things are looking a little better, I think I might be ready to do a bit more.  An introduction will be last, but that’s not too terribly taxing.  I’ll probably need to dig up a few more papers depending on whether I focus on a blockmodel entrance or mm entrance…or something else entirely.

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