Tuesday, July 3, 2012

Polling Mishaps

Diego Valle-Jones discusses the polling failures ahead of Sunday's election here:
Measuring the euclidian distance from the normalized "quick count" to the voting preferences, the most accurate pollsters were:  SDP Noticias-Covarrubias, Grupo Reforma, Ipsos-Bimsa, and UNO TV-María de las Hera. The worst performing pollsters were Milenio-GEA ISA and Indemerc.
In some of the cases, the problem would seem to be motivated by a bias for Peña Nieto--Milenio's largely fawning coverage of Peña Nieto squared with its polling that vastly overstated his popularity. Although I also wonder if there's a frontrunner bias in Mexican polls--AMLO fell short of the polls giving him a wide margin in 2006, and, if I remember correctly, I believe there was a similar dynamic in the governor's races in 2010.

Update: The polls actually weren't so far off in 2006. Most leaned toward AMLO in the weeks leading up to the election, but nothing like what just happened this time around.


Mexfiles said...

I'd have to go into the wayback machine, but in several state elections the 2010 polls had the numbers just about backwards. Us hippy lefty types have been saying for years not to trust the polling numbers... based too much on landlines (biased towards conservative voters) and those with the time and inclination to chat with strangers. And, not taking into account the general Mexican unwillingness to give the answer the questioner wants to hear. It'd be nice, too, if there was some way of polling voters as to their willingness to sell their vote, but that's asking the impossible.

pc said...

Actually Mexico has a lot of face to face polls, but no question that the polling is imperfect. 2010 was definitely pretty bad too.


Puebla can be excused a bit, because of the Marín tapes with the 17-year-old, but there was an almost across the board edge toward the PRI. Between 2010 and 2012, you could argue that it was an anti-left bias, but then 2006 flies in the face of that.

In 2009, María de las Heras was overly harsh toward the PRI, while Gabiente de Comunicación Estratégica almost nailed it. Make of that what you will.