Regular readers of the Mule will know that I am a bit of a data-mining junkie. Whenever I come across an interesting chart I start Googling for the underlying data. But, even with well-honed Google skills, it’s not always possible to find the data. Sometimes it is simply not publically available. I ran into just this problem recently. The recent Australian Federal budget triggered countless alarmist opinion pieces despairing that Australia would be “mired in debt” and this prompted me to do some research of my own. In the process, I came across a handy primer on the subject entitled “A history of public debt in Australia”. Written by a number of Australian Treasury employees in the Budget Policy Division, it included the chart below which shows the history of net Government debt (combining Commonwealth and State debt) over almost 40 years. The chart also includes forecasts for the next few years.
Australian Government Net Debt to Gross Domestic Product
While the paper is clearly quite recent (it has no publication date), the forecasts pre-date those included in the May budget, so I was interested in updating the chart with the latest Treasury forecasts. The underlying data does not appear to be published online and, since I do not work with the authors in the Budget Policy Division, I had to resort to special measures. I turned to a handy (and free, open source) little piece of software I have used a number of times to pinch data from charts. The software is called Engauge Digitizer and it allows you to import an image of a chart and extract the underlying data.
Engauge Digitizer Screenshot
For charts with points or curve segments, Engauge generally does a great job of automatically finding the data. For a column chart like the one I had found, the process is a little bit more manual, but with a bit of clicking on the tips of each of the columns in the image, I had my data. The chart below shows the data I obtained. One indication of the accuracy of the results is that the authors of the history paper noted that net debt had averaged 5.7% of gross domestic product (GDP) since 1970. Satisfyingly, the average of my extracted data over this period was also 5.7%.
Australian Government Net Debt to GDP (imported data)
Having obtained the data, I was then able to replace the forecasts with the more recent Treasury figures included in Budget Paper No. 1.
Australian Government Net Debt to GDP (updated forecasts)
For the alarmists who are worried about this growing debt, it is useful to put these forecasts in a global perspective. The chart below puts these Treasury forecasts alongside IMF forecasts for a number of other developed countries.
Global Debt to GDP Forecasts
Compared to the rest of the developed world, the global financial crisis is still not looking quite so scary for Australia. When it comes to the United Kingdom, rating agency Standard and Poor’s is even more pessimistic than the IMF and is concerned that their net debt could reach 100% of GDP and have accordingly changed the credit rating outlook for the UK to negative.
UPDATE: For anyone interested in getting hold of the data without resorting to scraping it from the images, I have uploaded it to Swivel. This dataset includes the most recent Treasury forecasts.