Publication months and award cycles

I’ve been wondering how release dates affect awards with annual qualification windows (which is pretty much all of them except the Nebula, I think). In other words, is there a bias toward work released early in a given year, presumably because that book or story had a chance to percolate through the readership and through the review and critical apparatus of our field?

I don’t have the time right now to do the research myself, but I suspect someone’s already covered this in exhaustive detail and I’m simply unaware of it yet. If I were to run this down myself, obvious factors to consider include normalizing for the nomination/judging lead time. For example, the Dick award finalists were just announced for an April award, while preliminary Hugo balloting will go on into the spring for a summer award, while the World Fantasy Award finalists won’t even be announced til sometime this summer. Does that mean that late-year releases have a better shot at the WFA than they do at the Hugo or the PKD? Or by the same token, do early-year releases fall off the radar too soon?

Intuitively, I suspect a slight bias toward early- and mid-year releases, but I know better than to trust my intuition when it comes to statistical questions. Any thoughts? Any evidence, either circumstantial or substantial?

Note: It doesn’t actually matter to me what the answer is. The psychology and market value of awards are completely different topics, that I’ve mentioned before and will probably tackle again. (Feel free to take them up in comments if you so desire, however.) This is me with intellectual curiosity about the process of awards. Neepery, not strategy, in other words.