And depending on how far back most of this data was collected, plausibly most of the Berkeley respondents were high school or college students (UC Berkeley alone has over 35,000 students), since for awhile that was the main demographic of Facebook users, and probably for awhile longer that was the main demographic of Facebook users willing to take personality tests.
Douglas_Knight is correct – the average age of users is quite low, at ~26 years old both for the high conscientiousness cities and the low conscientiousness cities.
Glad you liked it :-).
I used R for this analysis. Some resources that you might find relevant:
Practical Data Science with R has very nice introduction to exploratory data analysis.
Advanced R goes into more detail on the language.
The graphs were made using ggplot2.
I used the lme4 package for Bayesian hierarchical modeling. See, e.g. Getting Started with Mixed Effect Models in R.
Kaggle Kernels has some good sample scripts.
Douglas_Knight is correct – the average age of users is quite low, at ~26 years old both for the high conscientiousness cities and the low conscientiousness cities.
Thanks for the links!