The maps below represent instances of breast cancer mortality 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 mortality ratio (SMR) of breast 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 breast cancer mortality rate 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 dying from breast 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 dying from breast cancer compared to the general population in Iowa.

For example, suppose the risk probability of dying from breast 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 dying from breast cancer. The risk probability is calculated by comparing the SMR 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 SMR explained above) is 1.2, which again means that we estimate the risk of dying from breast cancer for that ZIP code to be 20 percent higher compared to Iowans in general.