Where Punxsutawney Phil got it more right than wrong, 1984-2014
Even though Phil’s predictions proved correct for some areas of the country, the difference in average temperatures between years he predicted an early spring (times he did not see his shadow) and years he did not (times he saw his shadow) varied by no more than a few degrees.
Phil’s predictions were more correct in these areas
Phil’s predictions were less correct in these areas
We all knew it was true, but it needs to be said: a groundhog is just a groundhog.
That said, we wanted to explore the relationship between Punxsutawney Phil’s predictions and a region’s temperature fluctuations during the six weeks after Groundhog Day (February 2) in each year. We assumed that years in which Phil saw his shadow would be colder than non-shadow years because, in shadow years, Phil predicts six more weeks of winter rather than an early spring.
For the past 30 years, we calculated the average daily temperatures during the six weeks after Groundhog Day for years in which Phil saw his shadow and compared them to temperatures of non-shadow years. With these averages we calculated something called a t-statistic, which takes into account the variations in temperatures within each region, and also indicates the statistical significance of our findings. These t-statistics determined whether Phil’s predictions were more or less correct in a given area as indicated in the color code in the map above.
The results show that while Phil was technically right more times than not in some cities (it’s bound to happen in some areas because temperatures across the country do not rise and fall uniformly), the average temperatures between shadow and non-shadow years were slight at best. So, much like how you won your last coin toss, Phil is “right” in these regions because of chance.
Some cities just happened to be warmer than others during a few weeks in February and March in years he didn’t see his shadow, but on average by only a very small margin, and certainly nothing that would constitute an early spring.
An outlier to this is Oklahoma City, Okla., which experienced shadow-seeing years that were 8.5 degrees cooler than non-shadow-seeing years. Conversely, Phil was exceptionally wrong with St. Petersburg, Fla., in which shadow years, on average, were 13.9 degrees warmer than non-shadow years.
SOURCE: National Oceanic and Atmospheric Administration, Wunderground.com, Stormfax.com. Published Jan. 30, 2015.