In previous blog posts, we examined the regional distribution of the donors and some properties of the data itself (steps, resting heart rate). This time we are reporting on the demographics of the donors, including age, gender, height and weight, which can be specified in the app.
A subset of donors (about 10%) provide voluntary information on age, gender, body size and weight in addition to their daily heart rate and step count. This data is not required for our work on COVID-19 but yields important information about how significantly the donor community deviates from a representative sample.
Around 60% of the donors who shared their demographic information are female, which means that there are three women for every two men. We also found that women donate 60% of all heart rate data, and 52% of the step count data.
The age distribution in our data is consistent with the age distribution of the total population, with a few deviations. The average age in Germany is 48 years, while the donor average is around 3.6 years older. This is due to an under-representation of young adults (age 20-35) combined with an over-representation of middle-aged adults (age 45-60). One possible reason for this disproportionate participation is age-related differences in risk perception. Young people may view themselves as less at risk of COVID-19 infection than people over age 45 or may not view the risk as severely. Another explanation may involve differential income distribution. Fitness tracking devices can be expensive, which may mean that they are more likely to be used by middle-aged adults who have a higher probability of higher income than young adults.
If we look at regional age distribution, we see that, not only is our overall donor population slightly older than the national average, but this same trend is exhibited by the individual federal states. Interestingly we see systematic differences between federal states.
Age and gender groups
A combined analysis of gender and age shows that women in our donor population are slightly younger than the national average, while male donors are slightly older. The average age among men is 50.2 years, which is about 4 years older than the average age for women (46.4 years).
As previously mentioned in the post Step by Step, we also examined the relationship between the number of steps and resting heart rate, which we then extended to different demographic groups. The results of this analysis await you in the next post.