For the moment let's ignore distribution models like meritocracy. Suppose a group has decided to divide their money in a certain way. What are the different formulas to measure how even or equal their division is, (irrespective of their personal needs, efforts, etc.), strictly mathematically speaking?
For instance, we could calculate an "index of inequality" as:
- the sum of all the differences in the incomes of people,
- Or as the sum of all differences from the average.
- Or from the median.
In short, there are many ways such an index might be defined, which affects how big a priority it is for the group. What are the main approaches of measuring the rate of equality of allocation of resources in general?