With the announcement of a Talent Corporation to bring home Malaysians who've gone overseas, this research — Plugging the Brain Drain — seems relevant. The findings are quite accessible to the layperson, but if you have a little statistical background, you'll definitely get a chance to grapple with some of the most extensive publicly-available analysis of our brain drain (that I know of, at any rate).
It has its flaws, especially with regard to data collection (full disclosure: Kian Ming and I helped the author with some of the statistical analysis), but it is of course only an initial foray into studying the reasons behind why Malaysians leave — or come home. If you have any comments, do post them here or contact the author, Evelyn Wong, directly. Also do share if you know of any similar studies, or scholars working on this topic!