The Verto Glossary: Index

As part of our monthly Verto Glossary series, we define an industry- or Verto-specific term, in an effort to make our content and the consumer-centric measurement more useful and easier to understand. In our last post, we discussed multitasking. This month, we turn our attention to indexing, a practice common in statistics and data science.

What is an index, or indexing?

Not to be confused with the Verto Index, an index (or indexing, when used as a verb) is a comparison of one entity against the average user for that entity. Last year, our data analyst Gautam Raj Moktan wrote an explainer about the various types of indexes that are often found across finance and the social science landscapes. Now, we’re taking a closer look at indexes and how they are used when we discuss data.

We’ve recently started to include index numbers in our charts of the week and select Verto Indexes to provide our readers with greater context around our insights. An index of 100 indicates the average for a given entity, while anything above or below 100 indicates an over-indexing or an under-indexing of that entity.

Indexes in the Wild: A Couple Examples from Verto Analytics

For example, in our recent Verto Index: Streaming Music, we examined the demographics (gender and age) of individuals who listened to a particular streaming service over the course of a month. Our data showed that Spotify is especially popular among younger listeners – especially those between the ages of 18-24, who comprise about a quarter of Spotify’s overall user base, but index a whopping 226 for this demographic (meaning that 18-24 year olds are 2.26 times more likely to use Spotify compared to the general population). In other words, when we are indexing against the average 18-24 year old, Spotify over-indexes by 126% in this age group.

Another example is from a recent chart of the week, where we compared the user bases for several popular online news sites. According to this dataset, Fox has a hard time attracting younger audiences: 18-24 year olds comprise less than 6% of its total audience, and index just 51, which means members of this age group are significantly underrepresented among Fox’s audience base when compared to the general population. In fact, Fox’s audience as a whole skews older: nearly half of its entire audience is aged 55 or older, a group that indexes 127, meaning that Fox over-indexes by 27% in this age group, compared to the general population.

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