This is the second week of this Thursday Threads experiment and already we have a bonus edition. Two other items crossed my browser today that were just too good to pass up: how statistical techniques are improving the aggregation of political polling and a visual representation of lifespan versus income over time.
Aggregating Political Polls for a Better View of Reality
This is the fourth article in a series on the accuracy of polls and polling averages. In the first two installments, we demonstrated that polls have been extremely accurate at forecasting the winners of governors’ and Senate races in recent years — much more so than you might expect based on intuition alone.
However, the fact that polls have been strong predictors in the past does not necessarily imply they will continue to be so in the future. In Part III, we took up one type of critique that I encounter frequently — that 2010 is an unusual political cycle, and that its idiosyncrasies may render the polling less accurate. While this is not an unreasonable hypothesis, we found it does not have any grounding in the evidence: the polls have done no worse in “unusual” political cycles like 1992, nor in “wave” years like 1994 and 2006, than in routine-seeming ones like 1996 and 1998.
There is another type of argument, however, that is potentially more troubling. It could be that, irrespective of the character of this political cycle, polling itself is in decline. This is a widely held view among political elites and many polling professionals — and quite a few of the readers of this blog, I might add.
There are some sound theoretical reasons to think that this is indeed the case. We’ll take these up today, in Part IV of the series.
Nate Silver crashed the political scene two and a half years ago using techniques applied from his background in statistics and a clear writing style that made the application of statistics readable. (Prior to becoming a political commentator, Nate used his skills on Major League Baseball statistics.) After the runaway success deriving predictions from the wealth of polling data plus some special sauce in the 2008 election cycle, he was picked up by the New York Times earlier this year. To understand more about his technique of weighting and averaging polling data, check out this four-part series called "The Uncanny Accuracy of Polling Averages":
- Why You Can't Trust Your Gut
- What the Numbers Say
- This Time, It's Different?
- Are the Polls Getting Worse?
200 Years that Changed the World
Looking for a five-minute primer on the last 200 years of global economic development and public-health improvements? Done:
The Planet Money blog at National Public Radio called attention this week to this 2009 video done by Hans Rosling that relates a rise in life span with a rise in personal income. If you have not seen Hans' interpretation of global statistics in his custom-built Gapminder application, you should take the next five minutes to be wowed by his visual presentation of what is arguably really dry statistics.