In a sign of the rapidly changing demographic profile of South Florida, Miami’s Spanish-lingo Univision affiliate, WLTV, has clinched its second consecutive sweep period as the top-rated TV station in the market.

In the Monday-Sunday total day (7 a.m.-1 a.m.) ranking, Univision O&O WLTV led with a 5.0 household rating and 12 share, followed by ABC affil WPLG (4.7/12); NBC O&O WTVJ (4.5/11); Fox affil WSVN (4.1/10) and CBS O&O WFOR (3.7/9). Univision was also the leader in the early evening news race, a key measure of station strength.

Reliability doubted

But general managers of the English-lingo stations in Miami, the nation’s 16th largest TV market, question the reliability of the Nielsen ratings generated in the just-concluded sweep (April 23-May 20).

The G.M.s say Nielsen Media Research’s local survey sample of about 500 households includes too many Hispanic households where Spanish is the dominant language — the viewers most likely to watch Spanish-lingo TV. In an effort to settle the dispute, the stations have hired accounting giant Ernst & Young to conduct an audit of Nielsen’s Miami operation, which should be completed this summer.