If you want to get away with a higher price, it helps to have a game based on an established console IP. The study notes that such titles have an average price of $6.12. It also mentions that the exact method Apple uses to sort apps in the top 100 is shrouded in secrecy, meaning that it's difficult to draw hard conclusions from the data. The actual sales numbers aren't published by Apple either. Thus, it's impossible to tell if a game with a higher price point is earning more than a cheaper game with a higher sales volume.
There's a lot of data to look over in the study and it's definitely worth a look for those interested in the business side of the games industry.