From time-to-time I share some analytics from my YouTube channel with my students (begging their forgiveness in advance for my self-indulgence). Many are fascinated (as I am) about things like number of views, demographics, and earnings. In the Demographics section I usually display the age profile of viewers over the lifetime of the channel, and comment that the biggest group are males in the 45-54 category (to which I belong myself). See these data below:
One of the most common questions I get is how does Google/YouTube know the age of someone who is viewing the video? If you are not logged on, or say you are using a public computer - how do they know? In the chart above there is no "Age unknown" category. One YouTube insider has told me that they "take a look at the viewers that are logged in and estimate what the total distribution is from there, taking into account some demographics are more likely to log in than others". Another told me that if "3 out of 10 people have the information available, the information will be extrapolated to the 7 with less fine manner".
One thing you can do is check out the analytics for subscribers only, as this is likely to be more accurate assuming people don't lie about their age when they create a YouTube account. When I do this a completely different picture emerges:
I would have expected both charts to be similar. However, in the second chart above you can see that the age profile is a lot younger than I had previously thought, with the 25-34 age category dominant, while the 45-54 category accounts for a much smaller number. I am mindful that younger people are possibly more likely to subscribe. While Google are getting better at profiling people, clearly there is some way to go to really have accuracy in this field.