We took 1,300 randomly selected undergraduates, we had them nominate their friends, and we followed both the random students and their friends daily in time to see whether or not they had the flu epidemic.
We namen 1300 willekeurige studenten die we hun vrienden lieten voordragen en we volgden zowel de studenten als hun vrienden elke dag om te zien of de griep bij ze rondging.