Last
Thursday the Wall Street Journal ran
an article about the Irish abortion vote, saying that it was expected to be
close and included these polling results in support of that statement.
Per
the footnotes, the poll was fielded by the Irish Times and Ipsos MRBI, both
reputable companies. The sample size was
1,200, a fairly decent size that should have yielded a statistically significant
result. And the margin of error was
3%. So at best, support for “Yes” should
have been 47%. (Hannon & Rocca, 208)
And
yet, when the votes were counted 66.4% voted “Yes.” (McDonald, Graham-Harrison
& Baker, 2018)
So what
went wrong here?
For starters,
the poll was taken on May 16, a week and a half before the actual vote. If all the undecideds voted “Yes,” that brings
the total to 61% - 64% if you include the margin of error. That’s closer. But what are the odds that all the undecideds
voted “Yes?”
More
likely the problem was the same thing that went wrong with the polls for Brexit
and the U.S. Presidential election. Our
polling techniques are broken.
They
rely on companies being able to get a reliable sample from calling people on
landlines. But these days when you rely
on landlines, you get a disproportionate amount of older, poorer, less educated
voters. They are anything but a random
sample.
Adding
online surveys to the mix can help capture younger voters, but here too, the
people who respond are not necessarily representative of the whole. And, deciding how to merge the data from the
different sources presents problems as well. (Knutson, 2016)
So,
where does that leave us?
When looking at research, pay
attention to sample size, sponsoring companies, and dates. But even if all those criteria look good, it’s
probably better not to rely on poll results anymore. They could be just more Fake News.
Hannon,
P. & Rocca, F. (2018, May 23) Catholic
Church Takes a Background Role Ahead of Ireland’s Abortion Vote. wsj.com. Retrieved May 29, 2018, from
McDonald,
H., Graham-Harrison, E., Baker, S. (2018, May 26) Ireland votes by landslide to legalise
abortion. theguardian.com. Retrieved May
29, 2018, from
Knutson,
R. (2016, October 27) Pollsters Scramble
As Fewer People Take Their Phone Calls. wsj.com Retrieved May 29, 2018, from https://www.wsj.com/articles/pollsters-scramble-as-fewer-people-take-their-phone-calls-1477577832