Internationally comparable cost of living data is crucial to forming sustainable expatriate pay policies and monitoring progress. Market exchange rates give misleading comparisons because they do not reflect salary purchasing power differences. Purchasing Power Parity (PPP) accounts for price differences between countries and so measures real quantities.
The purpose of an expatriate pay program is to maintain employee spending power and standard of living irrespective of global location. Salary Purchasing Power Parity (SPPP) is the amount of salary that equalizes the purchasing power of different currencies given the relative cost of the same basket of goods (cost of living) at the exchange rate versus one US Dollar. This means that a given salary, when converted into different currencies at the SPPP rates, will buy the same basket of goods and services in all countries.
Currency exchange rates are highly volatile as they are based on short-term factors and are subject to substantial distortions from speculative movements, economic outlook and government interventions. Currency exchange rates, on their own, do not in our view reflect cost of living changes in the short-term. Exchange rates, even when averaged over a period of time such as a year, are not a good measure of the comparative value of a salary in relation to its comparative international purchasing power. In the short to medium term at least, apparent changes in the comparative level of remuneration between one country and another may be principally a function of changes in the exchange rate as opposed to cost of living.
The basket of goods and services used in SPPP calculations is derived on an International basis and includes certain items often excluded from expatriate cost of living data (most notably housing costs), however any or all of the 13 basket groups can be included or excluded from a calculation. SPPP’s provide a reasonably good picture of the differences in standards of living for individual’s resident and paid in different countries.