Wednesday, January 13, 2010

Numbers are funny things

Now that we’re in the midst of the torrent of numbers justifying or repudiating the proposed health insurance reform, it may be time to give numbers a thought. And not only for this instance but for every instance where numbers are used to support or oppose some proposal. Their format and context is meaningful.

Numbers as absolute value or as percentages can easily misinform or deceive people into accepting or rejecting a fact for what it seems mean. Here are several examples:

If there was one murder in town last year and two this year it can be reported as either a 100% increase in murders or “only two” murders this year. Which one leaves you feeling most unsettled?

If I were lobbying for an increase in the Police Department budget, I’d use the 100% increase. If I were a beleaguered politician under attack for being soft on crime, I’d use the “only two” line.

In another example, voter turnout in an area with a growing population could be reported as the highest turnout (number of voters) ever or possibly as, “ the smallest percentage since …”. One way makes you feel good about the high turnout and the other makes you feel disappointed at the lower percentage turnout. Yet, in both cases, more people voted.

Another example. If there are 9 men in a bar, each making $10,000 and one man who makes one million dollars walks in, the average income in the bar goes from $ 10,000 to $100,000. Does that make those earning $10,000 any richer? Averages are tricky things, especially as to how they’re presented.

In our current discussion about health insurance (not health care), the large number of people without it 37,000,000 seems overwhelming. But the fact that’s only 10% of the population gives a different perspective. One in ten doesn’t seem to be as much as 37 million. And even here there’s a little bias. 37 million doesn’t seem as much to me as 37,000,000.

Know what numbers mean before you use them to make a decision. Think about it a little bit.