The South African Police Service may have overstated the drop in the ratio of serious crimes and understated an increase in others, according to the Institute for Security Studies.
The discrepancy in the data for the year through March 2013 was due to the police failing to revise crime ratios in the previous year to take account of new population statistics, the Pretoria-based ISS said in an e-mailed statement today. Police spokesman Solomon Makgale said in an e-mail that the figures for the actual number of crimes committed are accurate and there was no reason to revise the prior year’s ratios.
Official data published on Sept. 19 showed South Africa’s murder rate rose for the first time in six years to 31.3 per 100,000 people from 30.9 a year earlier. According to the ISS, while the police figures show a 0.5 percent drop in the murder rate in Western Cape province, where Cape Town is located, the calculation based on latest population statistics indicate a 10.1 percent increase.
“The statistical error means crime trends between the last two years as reported in September are wrong in every category,” the ISS said.
The 2011-12 crime statistics is based on a population estimate of 50.6 million. Data from the 2011 census, which was published in October 2012, put the population at 51.8 million.
There are no discrepancies with the total number of crimes published by the police and the ISS’s argument “only serves to confuse members of the public,” Makgale said.