The prices presented are average prices based on what's known as a seven-day rolling average. A seven-day rolling average price is the average of the current day’s price and the prices on the six previous days. In the case of retail prices it is the average of calendar days but in the case of Singapore Mogas 95 Unleaded it is the average of working days . A seven-day rolling average is used to smooth out the effect of the regular petrol price cycles in the larger metropolitan cities. Oil companies use a rolling average price for Singapore Mogas 95 Unleaded when determining their wholesale prices.
Lagged prices
Singapore Mogas 95 Unleaded prices are lagged by ten days as there is generally around a one to two week-time lag between changes in international prices and changes in retail prices in the five largest metropolitan cities because of the averaging formula used by refiners in Australia when setting their wholesale prices. The lag may be longer during times of significant price volatility.
There is a time delay between changes in international prices and changes in Australian wholesale prices. ACCC analysis indicates that the lag between changes in the Singapore Mogas 95 Unleaded price and in average daily wholesale prices in the five largest metropolitan cities is around five days. As such, average daily wholesale prices in the five largest metropolitan cities have been lagged by five days. There is a further lag of around five days between changes in average daily wholesale prices and changes in average daily retail prices in the five largest metropolitan cities.
How Singapore Mogas 95 Unleaded prices are calculated
The seven-day rolling average Singapore Mogas 95 Unleaded prices in Australian cents per litre (lagged by ten days) have been calculated using:
Singapore Mogas 95 Unleaded prices (only available on working days, ie Monday to Friday);
a seven day rolling average based on seven working days; and
an exchange rate from the Reserve Bank of Australia to determine the US dollar value of Singapore Mogas 95 Unleaded prices in Australian cents per litre.
It is important to note that factors other than international refined petrol prices and the Australian/United States dollar exchange rate affect domestic retail petrol prices. These other factors include the intensity of competition in local markets and changes in shipping freight rates.
