Wednesday, September 21, 2016

lies damned lies and statistics; riding motor bicycles in the night

The term was popularised  by Mark Twain , who attributed it to the British Prime Minister Benjamin Disraeli: "There are three kinds ofliesliesdamned lies, and statistics".

Statistics can be manipulated wittingly or unwittingly. I recently saw two instances of perhaps unwitting variety in our newspapers .

One was a a statement by a doctor, although I don't remember the name and the designation of the doctor, I remember it was a lady doctor and something to do with child health. The learned doctor has said that most of the children who suffer injuries, serious enough to receive treatment at hospitals, suffer those injuries when they are with their parents.
she may have arrived at this conclusion by comparing number of injuries  taking place  whilst child was with parents compared to home alone cases. so far her calculations have  no  weaknesses. but there is one factor that has not been taken into consideration. That is the fact that children in Srilanka most of the time stay with parents, at least one parent. And the other places where children stay long without parents, like schools or day care centers have been designed with many safety features and do not allow children to stray away from the premises. homes on the other hand allow much freedom and children move around freely in the neighborhood
Apart from all the other factors child staying with parents for 15 hours compared to 10 hours away has a greater probability to suffer injuries whilst with parents because the time spent with them is longer than time spent otherwise.

The other instance is a statement by police recently, by some police media guy . I cannot recall which police media since there are many media appendages in the police now. Anyway the statement was that most of the motor bike accidents happen in the daytime. Of course , it is obvious, because most of the motor bikes are ridden in the day time. probably 90% of the rides. 
And reason for more accidents to happen in day time is not that darkness makes it safer to ride but probability of accident taking place in daytime is much greater because number of people riding in daytime is much more than number in the night.

Disraeli is being proven correct more than 100 years after his death.


  1. This is called confounding in statistics. The famous example is the association between eating ice cream and drowning. One looked at sale of ice cream and number of cases of drowning over a period and concluded eating ice cream is related to drowning. But the real reason is sunny days. In sunny days eating ice cream is increase as well as number of people go for bathing in sea, rivers etc.


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