“Median age” does NOT mean the average age, it means the midpoint age where half of the viewers are older than that age and half of the viewers are younger.
But how do they know how old the people watching were!?
Nielsen’s national ratings panel includes around 40,000 homes and 100,000 people. Nielsen’s goal is to match its panel proportionately to the overall population. But to do this, they have to know who their panelists are. They do know who their panelists are! They know their names, where the live, how old they are, what race they are, what kind of job they have, whether they have cats and dogs, own their own home, are in the market for a 2nd mortgage or a new truck. They know all that stuff and more.
But how do they know who in the household was watching?
TL;DR: People Meter technology. Household members all have their own codes to distinguish the individual household members.
Does median age really matter?
I vote yes! But some of you wind up thinking you can play the median age logic out in ways that aren’t actually logical.
Example, the median age of World Series Game 7 last year was 50.5 which was lower than the 53.5 for game 6 but much higher than the 43.1 median age for game 5 of the NBA Finals in June.
So based only on the sentence above, which had more young adults 18-34? Game 7 of the World Series or Game 5 of the NBA finals?
Correct Answer: I don’t know and it’s not possible to tell from that data alone!
It isn’t possible. But, fortunately there’s more data. Game 7 of the World Series averaged 7.3 million adults 18-34 and game 5 of the NBA Finals averaged 5.7 million.
So although NBA Finals game 5 had a considerably younger median age, World Series game 7 had considerably more young adults. How can it be so? You can make it up in volume! Game 7 of the World Series averaged 40 million viewers and Game 5 of the NBA finals “only” averaged 24.5 million.
So both of these things can be (and are!) true: NBA Finals game 5 had a lower median age than game 7 of the World Series, but game 7 of the World Series still had more young adult viewers.
How is median age useful?
It is pretty useful for showing aging trends. Both broadly, across all of TV (where things have been graying for some time) and specifically for various properties and leagues, where, ultimately, the leagues are having a very hard time escaping the broader graying of TV trend.
You should read the above chart from Sports Business Journal as “holy #^%! in 2006 UFC’s median age was 34! Now it’s 49!” If the topic still interests you Sports Business Journal has done some great work on this front.