Thursday, October 4, 2012

Don't Count Your Chickens Before They Hatch

So with last night's debate the political bickering has reached a new high. I truly hope that voters will go in to this election well informed and truly vote their conscience, rather than buying the party line. I also hope that people learn to read and understand statistics before they use them to back or refute points that make them look silly.

This is not a statement one way or the other on the veracity of this specific information. My opinion on the following numerical information is immaterial, I am using it as an illustration.

The following I took off of FB. The original poster, and those who agreed, were discussing disproportionate US military spending in comparison to the rest of the world.

First, increasing military spending by $2 million is an inconsequential argument, when you are talking about Trillions. It is negligible to the point of being a virtual standstill. At this point rounding the number one way or the other could account for most of that. Be aware of the statistics in context of the whole.

Second, when talking about the spending in terms of real dollars, yes the USA is spending much more, but taken as a percentage of GDP, suddenly the gap is not nearly as large. Realize what the statistics say and what they don't. Be aware of which statistics people are comparing and which they are ignoring. This will often open your eyes.

Third, know when/where the numbers come from. When someone throws a pretty chart out in front of you demand sources. Some of the numbers on this wikipedia page are current as of 1996, others 1999, others throughout the first decade of this century, etc. When and where the statistics come from can greatly manipulate "fact".

Other important points:
Be aware of trends and sudden changes. I have seen crime rates jump or drop drastically based on how the statistics are counted. Are we counting the number reported, convicted, estimated, etc.? If something doesn't match be extra careful in your research.

Margins of error are important. Always check how accurate the people who put the numbers together in the first place think they are.

Numbers can be used to inform, numbers can be manipulated, sometimes use numbers to outright lie. Ask for sources, do research, and take numbers with a grain of salt. A statistician I respect often asks, "Does it pass the 'eyeball check'?" Meaning knowing what you know, are the statistics reasonable and do they seem to match your gut? As an example of this principle: If you are doing NBA analysis and your numbers don't tell you that Lebron, and Durrant are in the top several offensive players in the game, your stats might be flawed.

So when your favorite politician/party/talking head/social media spammer starts throwing out stats take a minute to think about what the numbers REALLY say.

Finally, remember 85% of statistics are made up on the spot. =)