The maps below represent instances of late-stage colorectal cancer in Iowa, broken down by ZIP code, for the years 2004 through 2018.
Risk Probability Persistence, 2004-2018
The above diagram shows the persistence of the standardized incidence ratio (SIR) of late-stage colorectal cancer for people living in each ZIP code in Iowa from 2004 to 2018 on a probability scale from 0.0 to 1.0. The color scale is designed as the probability that your ZIP code is higher than the state average with 0.5 being the state average. ZIP codes in red show areas that have a 12-year late-stage colorectal cancer incidence that is higher than the 15-year average for Iowa as a whole. ZIP codes in blue are lower than the Iowa average and ZIP codes in white are equal to the Iowa average.
Risk Probability by Time Period
The above diagrams are similar to the persistence maps, but break the maps down into smaller year ranges to show changes over time. They show the risk probability of developing late-stage colorectal cancer on a scale of 0.0 to 1.0 for people living in each ZIP code, with the state average being 0.5. A ZIP code with a risk probability greater than 0.5 indicates that an individual in that ZIP code has a higher probability of developing late-stage colorectal cancer compared to the general population in Iowa.
For example, suppose the risk probability of developing late-stage colorectal cancer in a ZIP code is 0.6. This means that the ZIP code has an estimated probability of 60 percent, which indicates individuals in that ZIP code have a probability above the state average of developing late-stage colorectal cancer. The risk probability is calculated by comparing the SIR of developing a type of cancer to a specific threshold (in this case 1.0). When hovering over this same ZIP code, the information may state that the relative risk (equivalent to the SIR explained above) is 1.2, which again means that we estimate the risk of late-stage colorectal cancer for that ZIP code to be 20 percent higher compared to Iowans in general.