Our society increasingly has more quantitative, probabilistic and dynamic facets. Therefore, it is increasingly important that journalists have a scientific culture in general and mathematics in particular.
Mathematics often suggests clarification or an alternative point of view.
Let’s start with a very simple example.
When Rudolph Giuliani, republican and white, won the mayor’s office in front of David Dinkins, democrat and black, the newspapers said that the vote of black people is more influenced by racial reasons than that of white people.
The evidence invoked was that 95% of blacks gave their vote to candidate Dinkins while only 75% of whites gave their vote to winning candidate Giuliani.
This table illustrates the above:
The estimate did not take into account that many black voters prefer to vote for any democratic candidate regardless of their skin color. While white voters have their most divided vote between democratic and republican candidates.
Putting the previous statement in numbers, we can make a table like the following, in which we can read that 80% of blacks vote for democratic candidates while they are only voted by 50% of whites.
We can quickly see that in the specific case of the election to the mayor of NY, the vote of black people for David Dinkins, democrat and black, was 15% higher than the usual 80% of the vote of black people who go for democrat candidates, which would indicate that 15% of black people voted Dinkins for racial reasons.
But let’s see now what happened with the white people’s vote. Their vote for Rudolph Giuliani, white and republican, was 25% higher than the usual 50% vote of white people for republican candidates, which would indicate that 25% of white people voted Giuliani for racial reasons.