Thought Toys · Chance & inference · Exhibit 87

Your friends really do have more friends than you.

Not on average for you specifically — for almost anyone. Line up every friendship in a network, pick one at random, then pick one of its two people at random: their expected number of friends always beats the network's true average, however evenly or unevenly popularity is spread. Drag the dial to see why — and pick a few random people to watch it happen to them personally.

120 people, drawn as a circle of friendships a hub everyone else

Ask a random friendship who's more popular

Click "pick someone at random" below to see one specific person's story.

your turn — drag the dial, or pick a random person

What you're seeing

Everyone here starts on an equal footing: a ring where each person is friends with their four nearest neighbors, nobody more connected than anyone else. As you raise the dial, a small fixed set of six people — the amber hubs — steadily gain extra friends from across the whole network, while almost everyone else's count barely moves. That's all "popularity" is in this model: most people staying near the baseline while a few pull far ahead.

Now play the sampling game in the panel above: line up every friendship as a pair, grab one at random, and look at one of its two people. You are far more likely to land on a hub than a uniformly random pick of people would suggest — not because hubs are special or lucky, but because every one of a hub's many friendships is a separate ticket in the drawing. A person with 40 friends holds 40 tickets; a person with 4 friends holds 4. Add up everyone's tickets and average the friend-count you land on, and hubs — who by definition have lots of tickets — pull that average up. This is the entire mechanism. No one's friend count changed by being asked about; the sampling just favors well-connected people, every time.

Click "pick someone at random" a few times. Most picks will be an ordinary person whose friends, on average, are more connected than they are — not a trick, just because most of their friends' friendship tickets include a hub somewhere nearby. Every so often you'll land on a hub instead, and see the pattern reverse for that one person. Both outcomes are the same phenomenon, viewed from two different seats at the same table.

The rule, exactly. For any network with people-degrees d1dn and m friendships (m ≥ 1), let μ be the population's true average friend count and let Q be the expected friend count of the person you land on by picking a uniformly random friendship and then a uniformly random one of its two people: μ = (1/n)·Σdi,   Q = Σdi² / (2m) Then, for any degree sequence whatsoever — this is Cauchy–Schwarz applied to the list of friend counts, not a special property of any one network — Q = μ + Var(d)/μ μ with equality only when every single person has exactly the same number of friends, i.e. Var(d)=0. Verified in node (improve/verify/87-friendship-paradox.js, 221 checks, on this exhibit's exact graph-building algorithm): the closed-form formula for Q is checked against an independently-enumerated average over every friendship's two endpoints; a negative control at hub strength 0 confirms the network is exactly regular and Q equals μ to floating-point precision — zero paradox when nobody is unusual; a live Monte Carlo simulation of the literal sampling procedure described above (not just the formula) is confirmed to match the closed-form value within a statistically derived tolerance; the gap Qμ is confirmed non-negative and non-decreasing across the full hub-strength range; and the graph-construction algorithm is confirmed to only ever add friendships as the dial rises, never remove or swap one, so dragging it grows the network rather than reshuffling it. Feld's original 1991 result, applied to any network: acquaintances, coauthors, follower graphs, even airports connected by routes.

Also in Chance & inference: The Galton board →

All 19 in Chance & inference
  1. 05The Galton board
  2. 06The Monty Hall problem
  3. 09Bayes' theorem
  4. 13Buffon's needle
  5. 14The central limit theorem
  6. 28Simpson's paradox
  7. 30Markov chains
  8. 31Averages that never settle
  9. 35The birthday paradox
  10. 38The drunkard's walk
  11. 39Zipf's law
  12. 40Benford's law
  13. 42The coupon collector's problem
  14. 48The wisdom of crowds
  15. 52Genetic drift
  16. 63The gaps are chaos. The count is law.
  17. 76Every bet here has an edge. Some sizes still go broke.
  18. 86Nobody got worse. The luck just didn't show up twice.
  19. 87Your friends really do have more friends than you. — you are here

Thought Toys — a cabinet of explorable explanations. Exhibit 87.