Do iPhone Ratings Matter?

I was very happy to discover the following image when I checked on Pocket Trivia: US History today:

Woohoo!  The US History Trivia game now has enough ratings (that number is five) to get an actual star ranking - with four five-star and one one-star rating, we have an average of a four star rating.  This is big news, because it now gives people something by which to evaluate the game.

This got me thinking - do these ratings actually affect downloads?  Traditional wisdom would indicate yes.  When it comes to customer reviews, people are willing to pay between 20-99% more for a five-star product than a four-star product. 78% of customers trust peer recommendations, but only 14% trust advertisements.

I went looking for some information - and found none.  Hmm.  So, as best I can tell, there is no empirical research our there that would indicate whether or not a high rating affects App downloads.  I tend to think it does, but I'd be curious to know the actual affect.

Anyone out there have any ideas?