Parameter estimates for obesity between exams 6 and 7 (1995–2001) using the SISa model framework.

The ‘average lifetime’ of a state is the average length of time an individual spends in this state before recovering. The ‘influence’ of a state is the cumulative probability that the infection will be passed from an infected to a susceptible connection before the infected individual recovers. The ‘cycle length’ is the average length of time between spontaneous infections. The basic reproductive ratio is calculated by setting . However this calculation is an approximation since it does not factor in fixed network structure. Since , the obesity epidemic would not be self-sustaining based on transmission alone.