When we share data insights in the U.S., we often look at DMAs, or designated market areas. There are 210 DMAs that make up the country, many based around big cities. These are sometimes referred to as “metro areas” as well. While we are thoughtful of viewership throughout the country, when we want a high-level look at the areas driving the highest rate of viewership compared to the country overall, we typically focus on the 25 largest of the DMAs.
Fun fact: the 25 largest DMAs represent almost exactly half (49.7%) of the U.S. population. Outside of the U.S., we similarly break out viewership by region. For example, in the U.K., we look at BBC regions, in Germany we look at German States, and in Australia we look at AU TAM regions.
When we say a specific location “over-indexes,” it simply means households in that area watched a particular program at a higher rate when compared to the country overall. And “under-index” would be the opposite – watching at a lower rate when compared to the country overall.
What does it mean when a city over- or under-indexes?
