I love numbers. I love the story they can tell. But mostly, I love how they can deceive without lying.
Every day we are bombarded with statistics. Many of us are influence by what we read – me included. Sometimes I am fooled by them, so I have developed some rules to protect myself.
Rule #1: Be Sceptical. When at University in the 80s, I read an article in the Daily Mail that suggested a young boy spent £300 a day (money he stole from his parents) to play Space Invaders at Dudley Zoo. Assuming the boy consistently played the shortest game possible, the zoo would have to open for more than 24 hours a day for this to be possible (I confirmed the game was only available for eight hours). I haven’t read the Daily Mail since – mostly because I spent my grant on Space Invaders.
Rule #2: Don’t believe someone else’s interpretation of the data – verify it yourself. In 2017, several news sites published the headline “being single will kill you faster than being obese”. It won’t. Being young and single is dangerous; being lonely, is more dangerous. So, if you plan to eat too much, do so with friends.
Rule #3: Measure the Significance. I mentioned to Alison, my wife, that a bottle of wine a week increases your risk of cancer. Her response “Do you want to strip all the joy from my life?! Didn’t you do enough when you forced me to marry you!” As it turns out, the study shows drinking modest amounts of alcohol modestly increases your overall lifetime risk of some cancers: statistically significant, but not personally significant. If you are going to quote statistics to your wife, make sure it will help her, not break up your marriage.
Rule #4: Consider the big picture. Back to Alison… if she were to drink one glass of red wine each day (1 1/8 bottles a week), she’d live longer. Supposedly, the protection red wine provides against heart disease and dementia outweighs the increased risk of cancer: although I image this study was sponsored by the wine industry.
Rule #5: Statisticians are humans too. There are good statisticians and bad statisticians and statisticians who are incented to ignore the facts. You don’t now which is which.
I often use statistics to win an argument. I promise to tell the truth, and nothing but the truth (but not the whole truth). I’ll never lie, but if its to my advantage, I may not put them in your context, I’ll conveniently omit key facts and ignore the bigger picture. These things are your responsibility.
P.S. If a statistic supports your argument, don’t look at it too closely. It is depressing to learn you are wrong. And depression can kill you.