William Vambenepe's blog

Another off-topic entry to add to the CrazyStats category. Today’s NPR’s “All Things Considered” included a report called “States Fret at Easing of Border Security Plan” which talked about “Operation Jump Start”, so described:

“For about a year, National Guard troops have been rotating in and out of outposts along the [US-Mexico] border. Soldiers stayed visible under blue tents right on the border to deter illegal crossers while scanning the landscape, reporting anyone who did cross.”

It then goes on:

“The deterrent worked. The number of crossers apprehended by the Border Patrol since last October is down by about one-third, while drug seizures are up.”

The implication seems to be that would-be illegal immigrants were deterred by the presence of the troops and that drug traffickers were not deterred but were more often caught thanks to the help of the troops (who presumably either directly caught drug carriers or freed up Border Patrol resources to go after them). Success! But what if the result had been the exact opposite? More crossers apprehended and fewer drug seizures. Couldn’t that just as easily be interpreted to mean that the troops helped in catching more crossers while providing reinforcements that deterred drug traffickers? When opposite results can be interpreted to both mean success the test is suspicious.

After the 12% temperature rise, I recently ran into another creative use of percentages. Since I expect to run into many more of these (based on how many I’ve noticed in the past) and since they’re fun to point out I’ve created a new CrazyStats category.

This instance comes from a print advertisement for Samsung TVs, stating that their TVs with a 16:10 aspect ratio offer 30% more viewing surface than a 4:3 TV. Sorry, I don’t have a link but this advertisement (for computer monitors instead of TVs) repeats the “larger than 4:3 monitor” claim several times, albeit without quantifying it. This comparison makes no sense until you fix one dimension. And obviously it is to the advantage of the 16:10 screens to fix the height as being common between the two screens and then compare the surface (but even then, you only get a 20% advantage for the 16:10 compared to the 4:3, I don’t know how they came up with 30%). But if you fix the width as being the same then it’s the 4:3 that offers 20% more viewing surface…

Not that I don’t agree that 16:10 is a more useful aspect ratio (that’s what I bought for my monitor at home). But the “larger than 4:3″ claim is meaningless. Next thing you know, people will start marketing 4:3 monitors as “16:12″ to make them seem “bigger” than 16:10 monitors.

Here is another one to file in the “lies, damn lies and statistics” category: an article dated yesterday titled “Dutch bask in warmest autumn in three centuries” that starts with “The autumn of 2006 has been the warmest in the Netherlands for over 300 years, 12.5 percent hotter than the previous year which was already a record, meteorologists said.” We find out later where this 12.5% comes from: “The average temperature for the months leading up to November 17 was up to 13.5 degrees (56 degrees F), as compared to 12 degrees last year.” Except that such percentages don’t make much sense when applied to units that have an arbitrary zero. The same calculation using Fahrenheit degrees results in only a 5% temperature rise. Use the Kelvin scale and you’re down to a paltry 0.5% rise. Now imagine that a city has a 0.5C average one year and 1.5C average the next year. That’s a 200% increase in temperature! And if you live in a place that at some point gets a 0 degree temperature average, I would recommend moving out before the next year because you’re very likely to experience a terrifying *infinite* rise (or decrease) in temperature the following year!

This article comes from Agence France-Presse. And the French education system is criticized for putting too much emphasis on Mathematics…