Monday, May 28, 2007

Faking Precision

#247 Faking Precision

This is really, really cool. You can fake precision using real numbers and no one will much think about your trickery.

Here’s a quote from the label of a waterless hand sanitizer bottle: “Kills 99.99% of Most Common Germs That May Make You Sick.”

Wow, powerful stuff, right? Zaps pretty much everything dangerous. A virtual instant sterilization. Only .01% left when you’re finished.

Maybe.

But look at it closely.

“Kills 99.99% of most common germs…”

“Most” can mean just over half. Say 50.000001% So, really, this stuff can kill about 99% of about half” So, that a more precise rendering would be “kills about half” of “common germs that may make you sick.”

But what is COMMON? And what does “MAY” make you sick mean? If these germs may make you sick, they also may not make you sick.

And while we’re at it, what does “sick” mean? Are we talking about Yellow Fever? Or maybe a little bit of itchiness? Are we talking about cancer? Or maybe a sniffle?

The thing sounds downright scientific. But there are so many variables, the figure means 100.00% of nothing. (or 0% of everything.)

So, here we have an example of hiding behind number-supported imprecision. But it’s only one example.

Here’s another, the famed Dow Jones Industrial Average. This is calculated by taking the closing prices of 30 stocks, adding them together and divided by 30, right? Wrong. The DJIA is “weighted.” Stocks are given values over and above their actual price. That’s why when you add up the stock prices and divide by 30, you get nothing like what Dow reports as the day’s closing figure.

How about your body temperature? It’s 98.6, right? Normal. But not always. Some people are a little higher or a little lower most of the time and they’ve learned not to panic after reading the thermometer.

We won’t get into the way surveys are taken, because that’s too long and complicated for this venue. But suffice it to say asking “are you willing to spend $120 million on a new school building?” will not elicit the same percentage of “yes” answers as “do you want your children to have a good education in better surroundings than they now have?”

And “do you want to win the war on terror?” will not get the same “yes” votes as “should we send more Americans to fight in Iraq?”

This example should ring true: “The temperature is 87 degrees.” Very precise. Except also meaningless, because chances are you can’t feel the difference between 85 and 89.

One well known media company has a complex formula for determining the value of employee bonuses. The formula is used to determine the value of something akin to a stock certificate. But the number of these faux stocks awarded to an individual employee, is decided by whim. So the precise accounting is meaningless and the amount of the bonus dependent not on the value of the paper, but on the mood or attitude of the supervisor.

Numbers are, indeed, precise. What we do with them often is more camouflage than calculation.

(A briefer version of this Wessay was used on my WBLF radio program in May, 2007.)

I'm Wes Richards, my opinions are my own, but you're welcome to them.

(c) 2007 WJR

1 comment:

Suzanna said...

i completely agree with you. that's what i noticed long ago and it has been annoying me a lot. sometimes shoppers can be the way too stupid to understand that the price "from $99.95" does not mean 99.95 but OVER it. it is everywhere. numbers have learned to lie.