Any of you guys know how to calculate gini coefficients?

Question

I'm gonna give you an example:

income distribution:

100 for 50 people ; 200 for 25 people ; 300 for 75 ; 400 for 25;

Hence:

total income = 1000, total number of people = 175.

calculate the gini coefficient..

Answer 1

order them by ave income and calculate the cumulative income curve and the area under curve

people 50   have 100  ave=2    p *** =50 i ***=100

people  75  have 300  ave=4   p ***=125 i ***=400

people 25   have 200  ave=8   p ***= 150 i ***=600

people  25  have  400 ave=16  p ***=175 i ***=1000

then look at def  in http://en.wikipedia.org/wiki/Gini_coeffi...

Note: Yahoo think my abbreviation for cumulative is a dirty work so put in ***

Answer 2

total income is not 1000

TI=100*50+200*25+300*75+400*25

TI=43.100

Gini = real difference of income - apsolute equality of income * 2

apsolute equality of income is 43.100/175= 246

I don't know how to calculate real difference of income cause in your example there are 4 separate groups.