Friendship Paradox

Age 11 to 16

This classroom activity is part of the Disease Dynamics collection

This activity shows that more than just disease dynamics can be gleaned from analysing network structures.

Although networks are vital for understanding disease transmission in a population, they can be used for several other uses beyond public health.  This can include sociology, psychology, criminology, political science, computer science etc.

This activity builds on work by sociologist Scott Feld (Feld S, (1991) Why Your Friends Have More Friends Than You Do, American Journal of Sociology, Vol 96, No 6. (May 1991) pp 1464-1477) to show that on average, your friends have more friends than you.

Resources: Slides (PowerPoint or PDF), Printable Friendship Graph (PowerPoint or PDF)

Curriculum Link

  • Describe, interpret and compare observed distributions of a single variable through graphical representations, as well as mean, median, mode, range and outliers.


  • To establish that you can learn a variety of things from network analysis
  • To revisit averages

Activities (Small Groups)

Start with person 1 and count the number of friends they have.

Count how many friends each of their friends have, and calculate the average number of friends they have.

Complete with all of the people in the network; the chart can be printed out for students to fill in.

Questions for thought

Does this surprise you?

What else could you analyse on a network?