Private equity: returns and size

Is there a paper looking at the return to private equity funds compared to the size? Is the data available?

FT.com / Lex - Lex: Private equity: "Interestingly, in the US, it is not clear that size confers much of an advantage. According to data from Private Equity Intelligence, of a sample 77 US funds that were in the top quartile by size between 1988 and 2003, only a tiny majority beat the median internal rate of return hardly a head start. Intriguingly, large European funds did a little better relative to the benchmark. One factor that might explain this difference is the higher degree of competition in the US. "