The GPD Index – also known as the Dan Murphy Equation – is one of the prime indicators of stress and/or sanctity in the Perth suburbs.
Other offices measure the average income, crime statistics, or ethnic make-up of the metro area and try to predict where the state and council services will be needed. The Grog Per Day figure is far more accurate and a lot more fun to measure.
Starting with a basic form that asks whether you have had a drink on any given day, and proceeding on through a series of ever more personal question, the GPD survey attempts to elicit who is going to be blind drunk on any particular day, as well as where and when. Given an accurate map of the boozers, the Department of Crime can call round their houses and steal their motor vehicles and the contents of their garden sheds with impunity.
There are factors that need to be taken into account – some people surveyed can hold their liquor better than others – some have no cars and nothing in the garden shed worth stealing. Few vicious guard dogs drink, and this can disrupt the most efficient collection service.
The inclusion of migrants who do not drink has also skewed the findings in the last two decades. Several suburbs are so rife with sobriety that they have been declared a No-Go zone by the department. Fortunately, they may be side-by-side with suburbs that house migrants from largely criminal cultures and the resultant bitter warfare can help to redress the statistical imbalance. In this case no-one really loses, least of all the number crunchers of the state of Western Australia.