MANILA - As it faced criticism over surveys showing a decline in President Rodrigo Duterte's net satisfaction rating, the Social Weather Stations (SWS) has defended its methodology and assured the public that it is faithful to data and does not exaggerate.

In an opinion piece published Saturday on the Philippine Daily Inquirer, SWS president Mahar Mangahas stressed that he is confident in the research firm's methodology.

"We focus on what seems to have happened over time, according to our measurements. Being confident about our methodology, we do not worry about comparing our measurements with those of other people," he said.

It was an apparent reference to divergent results of SWS and Pulse Asia survey results taken in September: while SWS showed a dip in the President's ratings, Pulse Asia's showed that Duterte has retained "big majority" approval and trust ratings

Mangahas chided those who erroneously use SWS data to give weight to their opinion.

For one, calling Duterte's ratings decline a "free fall" or a "plunge" is exaggerated, he said.

"Exaggeration is anyone’s right to do; it’s part of free speech. But it detracts from the quality of applied science. SWS tries hard to avoid it," he said.

He also explained that any report tackling satisfaction in the general performance of an administration is correlated but not identical to satisfaction with the personal performance of the President.

These also depend on the subject matter, be it hunger, recovery of the "hidden wealth" of the late strongman Ferdinand Marcos and his cronies, and the traffic problem, among others.

"Taking careful account of the dynamics of public opinion on various subjects is a tool for rendering better service to the citizenry. Muddling the accounts by exaggerations is a disservice to the people," he said.

In a separate poll released earlier this week, the SWS said the net satisfaction rating of Duterte’s administration remains "very good" but declined in Luzon and among the country’s poorest.

The SWS survey, done on Sept. 23 to 27, found 71 percent of adult Filipinos satisfied, 16 percent neither satisfied nor dissatisfied, and 13 percent dissatisfied with the general performance of the national administration.