Note: The Gini coefficient is defined as one minus twice the area under the cumulative probability distribution (CPD). The Ginis computed here do not have the properties of a “true” Gini coefficient. For example, a true Gini must lie between zero and one. The Ginis calculated here could be negative if low-income individuals had a higher ownership rate than high- income individuals.
Using percent ownership. The percent ownership rates by decile are transformed into a discrete probability distribution. The formula is: pi = ri /3ri the sum is over i = 1 to 10 where pi is the fraction of all households that own the durable good who are in income decile i or ri is the actual ownership rate for the ith decile.