A decline in advocacy, or the "net promotor score", was the fate of three out of four of Australia's major banks over the last year, a research house has found.This decline (see chart) "has been caused by a combination of factors that relate to their reputation, their service levels and pricing strategies", Dhruba Gupta, head of banking research at DBM, said yesterday.DBM, better known for a long-running study of business banking, has widened its research to develop a "consumer atlas" to promote to the local banking industry.Gupta said that "overall 2016 was not the best year for the Big Four banks, with advocacy generally falling for all of them during the year.    "This is a concern because it can make it more difficult for Australia's biggest institutions to realise their full potential.""With the recently announced interest rate rises in March by some of these banks it will be interesting to see how they fare in the coming months as service providers for the community," said Gupta."Despite their recent challenges, the Big Four banks still have the opportunity to regain their advocacy if they get a few things right - the things that are important to a majority of us."The net promoter score among the Big Four banks shows that National Australia Bank retains an edge, and the only bank to advance on the NPS measure over 2016, Gupta said.