Death data scrutinised

THE question if the mine fire increased the mortality rate was further examined at an additional hearing of the Hazelwood Mine Fire Inquiry yesterday.

A joint report from six witnesses with expertise in biostatistics, epidemiology and public health in relation to fire agreed there was an increase in deaths during the 45 day mine fire last year, but challenged a “99 per cent probability” analysis.

The report was commissioned by the inquiry board tasked by the State Government to investigate the blaze.

Lead by the honourable Bernard Teague, the hearing in Melbourne considered new analysis by University of Queensland statistician Adrian Barnett, who first presented his research to the board in September.

Dr Barnett’s latest report said there was a 99 per cent probability of an increase in deaths during the fire, with an estimated 23 deaths.

The figure was larger than the 79 per cent to 89 per cent probability and 10 to 14 additional deaths in previous analyses.

The Registry Births Deaths and Marriages data was first gathered by mine fire advocacy group Voices of the Valley in the four postcodes surrounding the Hazelwood mine.

Dr Barnett said the increase in deaths occurred because the analysis used daily data whereas the previous analyses used monthly data.

“The monthly data was a crude estimate of exposure… moving from monthly to daily data reduces measure for error,” he said.

However, new witness McCloud Consulting Group director and principal statistician Dr Phillip McCloud said the increased number of deaths was within the boundaries of random variation.

Dr McCloud said in fields such as medical science, clinical trials, public health and time series of death statistics, the task of understanding causality was “clouded” because of random variation.

“It is well understood that unexpected peaks or troughs in time series of data are often the result of random variation,” he said.

GDF SUEZ queens council Anthony Neal cross examined Dr McCloud’s findings of Mr Barnett’s data, which also critiqued the absence of direct evidence such as death certificates that report death was caused by smoke, carbon monoxide or other pollutants emanating from the mine fire.

“In my opinion the numbers alone are not adequate to justify a conclusion that the pollution from the mine fire caused the increase in deaths compared to previous years,” Mr McCloud said.

Check for updates and full coverage in Monday’s Express