Tuesday, February 1, 2011

Editor's Math Skills Decline Faster Than Teen's Alcohol Use

Today's Charlotte Sun editorial repeats errors and miscalculations made by staff writer Greg Martin in his Jan. 26 article about a statistical decline in self-reported drug and alcohol use among area middle- and high school students.

Both the news article and editorial trumpet good news: Self-reported substance use among school-attending teens is in a fairly steady downward trend in Charlotte County, according to the survey. And so are the grown-ups' math skills. Here are the editorial writer's claims, repeating the reporter's flawed grasp of FCAT math:

According to the 2010 report, the percentage of county middle and high school students who said they had used alcohol within the past 30 days has decreased 16.7 percent from 2002. Binge drinking decreased 7.2 percent and tobacco use decreased 8.9 percent.

Not even close. First-year journalism students know percentages and percentage points are quite different. Consider this example: Suppose a report says 10 percent of Easter Islanders got tattoos last year, but this year only 8 percent got inked. Reporters would correctly report a 2-point difference -- representing a 20-percent decrease from last year.

Here's what the local writers might have correctly reported:

The survey says 42.2 percent of the surveyed students in 2002 reported using alcohol in the last 30 days compared to 27.6 percent in 2010. That is a 14.6-point difference, representing a 34.5-percent decline.
In 2002, some 23.8 percent of the surveyed reported binge drinking in the last 30 days compared to 15.1 percent in 2010. That's a 8.7-point difference, representing a 36.5-percent decline.
In 2002, some 20.7 percent of the surveyed reported using tobacco compared to 13.8-percent in 2010. That's a 6.9-point decline, representing a 33-percent decline.
The first error by both reporter and editor is not doing the math -- not even a round-number estimate in their heads (OWW's first red flag). The second error is not comparing what they wrote with what they read.

Which brings OWW to the next question: Where the heck did the reporter get his numbers? Looking Table 5, we see these percentages -- none of which substract out to 16.7, 7.2 or 8.9:

Substance _ _ 2002 -- 2010
Alcohol .............. 42.2 -- 27.6
Binge Drinking ... 23.8 -- 15.1
Cigarettes .......... 20.7 -- 13.8

The closest OWW can come to tracking down this error is at least some of the reporter's misinterpreted data comes from Table 4, which reports "lifetime trends," and not Table 5, which reports 30-day past usage.

The news is good but the math is awful -- as with another headline story in a sister paper, The Journal of Lake Placid ....where Editor George Duncan claims via cliche that time travels faster when there's a crafts fair on the horizon. But, the last time we checked, every day lasts 24 hours and every hour lasts 60 minutes.

1 comment:

  1. They don't read their own paper when the AP says the DOW declined by 13 POINTS, not 13 percent? Hard to believe ...