Each January, your OMERS pension increases by 100% of the increase in the Canadian Consumer Price Index (CPI), up to a maximum of 6%. If the CPI is greater than 6%, the excess is carried over for use in future years.
The CPI measures approximate changes in the cost of living based on the price of a basket of goods that an average Canadian household buys. The basket includes food, housing, transportation, energy, furniture, clothing and recreation. More about the CPI is at Statistics Canada's website