If 2012 was Gallup’s only error, I might be more willing to forgive. The fact is that Gallup has only pegged the correct winner in 60% of elections since 1976 – which is not much better than a coin flip. That record drops to 25% since 2000. In four elections since 1976 in which the election margin was less than five points, Gallup has not called the right winner.
The fact is, however, Gallup’s presidential polling miscues are only the tip of the iceberg. After an extended investigation by Mark Blumenthal, into Gallup’s long-standing racial imbalance in its adult sample (which is supposed to reflect the adult population), Gallup claimed it was weighting its sample to the cell and telephone population. Of course, not everyone has a telephone. Gallup said it was making “judgement calls” and, regrettably, stuck by its methods.
It was only by October that Gallup revealed new, “slight” weight changes, when everyone else was showing something different than it was. The fact that Gallup altered its methods in the middle of the campaign, and long after its flaws had been pointed out, had to make even Gallup’s most ardent defenders flinch.