The lack of balance is an example of what John F. Harris of Politico has called “centrist bias.” As he has written, “This bias is marked by an instinctual suspicion of anything suggesting ideological zealotry, an admiration for difference-splitting, a conviction that politics should be a tidier and more rational process than it usually is.” –David Leonhardt (NYT)
There are three statistical measures of central tendency: the arithmetic mean, the median and the mode. The harmonic and the geometric means are other alternative ways to measure the mean.
The arithmetic mean can be heavily influenced by extreme values (outliers). That’s why the Census Bureau usually reports median income as a more reliable measure of central tendency to describe the average income in a population.
Is the proclivity to split differences a biased way to estimate the true mean of a population? It certainly is when averaging outliers.
An analogy may serve to discern between centrist bias and a balanced center.
- Centrist bias: tripod with legs of equal length regardless of the surface.
- Balanced center: legs of tripod adjusted in length until the air bubble of the level hits the center for a given surface.