Returns on equity for New Zealand banks are in the middle of the range for the nation's listed companies, says a study released yesterday.The study was released by the New Zealand Bankers' Association but compiled by Palmerston North's Massey University.The NZBA said average bank returns on equity from 2008 to 2012 ranged from 7.5 per cent to 16.3 per cent, well below the top average return for a New Zealand listed company - the 31.7 per cent return registered by Restaurant Brands New Zealand.NZBA chief executive Kirk Hope said the study had been done because "there are a lot of views on bank profitability which we felt were overstated." In June, business news website interest.co.nz claimed that New Zealand's Big Four banks were the world's most profitable, above even their Australian parents. It estimated a 1.39 per cent average pre-tax profit as a percentage of total assets across New Zealand's Big Four (ANZ NZ; CBA's ASB; NAB's Bank of New Zealand; and Westpac NZ). Australian banks recorded a figure of 1.19 per cent.