Net Power Parity = Purchasing Power parity - Earning Power Parity

The Purchasing Power Parity (PPP) is an economic technique used when attempting to determine the relative values of two currencies,It is a theory of long-term equilibrium exchange rates based on relative price levels of two countries. The idea originated with the School of Salamanca in the 16th century and was developed in its modern form by Gustav Cassel in 1918.The concept is founded on the law of one price; the idea that in absence of transaction costs, identical goods will have the same price in different markets.

The theory states that,in an ideally efficient market, identical goods should have only one price, uses the long-term equilibrium exchange rate of two currencies to equalize their purchasing power.

This purchasing power exchange rate equalizes the purchasing power of different currencies in their home countries for a given basket of goods.

Above Definition and technique of Purchasing Power Parity is a traditional definition and explanation, which focus only on spending side of Purchasing Power parity and not the earning or Income side of Purchasing Power Parity.

Purchasing Power of the currency is based on two main factors like two sides of the same coin.

First factor would be:
What can a same basket of goods cost in two countries with a same unit of currency?
If a basket of goods consist of 20 food items

Second Factor would be:
How many hours an individual has to work in order to earn enough to buy same basket of goods in both countries?