Visualising the cancer burden
The cancer burden (cancer diagnosis and excess deaths) in each geographical area is displayed in comparison to the Australian average using gradated colours. Areas that have a diagnosis rate below the Australian average are shades of blue, those above the Australian average are shades of orange/red, with yellow representing those around the Australian average. The darker the colour, the more extreme the estimate is.
The map of Australia can be zoomed in and out, similar to Google Maps.
The Atlas can switch between male only, female only, or persons (combined male and female). It also allows comparisons between cancer types and indicators within one area and between areas.
Regional summary plots
Australia is a very large country, and the national map is dominated by geographically large, sparsely populated rural areas. However, most of the population live in the capital cities. Because of the scale of the national map, it is difficult to see details of geographical differences within those densely-populated capital cities. To overcome this, select the ‘Estimate overview’ button to see a graph showing the distribution of the cancer burden within the eight capital city regions of Australia. Other region groupings are also available.
There are three ways to view these graphs:
Frequency: the number of SA2-specific estimates within each region
Proportion: the percentage of SA2-specific estimates within each region
Distribution: the spread of SA2-specific estimates. These show the median and range of values within each region. The median is shown by the large circle in the middle. The solid white line represents 50% of all estimates, while the faint line represents 80% of all estimates. The full range of estimates is shown by the detached circles.
Corresponding graphs are also available by remoteness, area level socioeconomic disadvantage, and state or territory
Within the cancer selection panel, tree maps show the relative burden of each cancer type in terms of numbers of cancers diagnosed or excess deaths. The larger the block, the greater the cancer burden for that cancer. The importance is shown as the proportion of the block shaded green, with the entire area representing ‘all cancers’
A single number is not enough to understand the cancer burden in an area. As is always the case with statistical estimates, each estimate has a degree of uncertainty, or imprecision, around it. The larger the uncertainty associated with an estimate, the less convincing it is that this is the true value. Conversely, the smaller the uncertainty associated with an estimate, and the further away from the Australian average it is, the more likely it is to reflect a real difference. Areas with smaller populations are generally more likely to have wider uncertainty around them. The level of uncertainty is demonstrated in three ways.
In V plots, the y-axis shows the confidence or probability that the estimate is different to the Australian average. The x-axis shows the value of the estimate in relation to the Australian average. The Australian average is shown at 1 on the bottom axis. Dots to the left of the Australian average are lower, dots to the right of the Australian average are higher. There is greater certainty that the dots closer to the top of the graph are more likely to be real differences, while there is more uncertainty about the true value of the dots nearer to the bottom of the V plot (in the slightly lighter region).
As an example, the dot for Inverell for ‘all cancers combined’ is to the right of the Australian average, with a high probability (inside the darker shaded region) of being different to the Australian average. This suggests that we can confidently interpret this estimate as the diagnosis rate for this cancer is 8% higher than the Australian average and likely to be a real difference.
This interpretation is shown in the panel that pops up when you select an individual SA2 area on the map. The square for diagnoses of ‘all cancers combined’ is orange (meaning higher than the Australian average), with the text showing “8% above the Australian average, likely to be a real difference” under “All cancers”.
The Wave plot indicates the level of uncertainty for the specific estimate for Inverell example. The small white circle in the centre shows the reported estimate, while the horizontal line shows the range in which we are fairly confident the true estimate lies. The height of the shaded curve, or wave, reflects the probability that the true estimate lies in that range.
The transparency of the colours in the maps will show how confident we are that the differences are real differences (no transparency), rather than being due to chance (lots of transparency). The background colour of the maps is yellow (representing the Australian average). This means that if an estimate for an area has a lot of uncertainty about it, then we interpret that estimate as being no different to the Australian average.