The central government has responded to criticism it miscalculates inflation by excluding property prices from the consumer price index, saying such purchases are investments, not consumption, the South China Morning Post reported. Some media and chat-room contributors have cast doubt on the index's credibility, arguing that housing costs represent a large portion of people's spending. Since last year, academics have been calling for property purchases to be included in the index, along with the costs of education and medical services. Shenzhen property activist Zou Tao said the global practice of disregarding property prices in the consumer price index should not be applied on the mainland because property has become a main part of people's spending, accounting for 50 to 60% of their incomes. But an unnamed spokesman from the National Bureau of Statistics defended the practice. "Based on statistical accounts, more people are buying properties to transfer their current assets to fixed ones, and thus the purchase of commercial-residential buildings usually fall into the category of investment, not an act of consumption," the spokesman said.