Table 1.

Data and model quantities, including notation and a brief description of their meaning. Groups correspond to: quantities measured in both the data and model; empirical quantities; parameters used by the model; and parameters estimated from the data.

quantity	description
data/model quantities
Ra(t), Rt(t)	fraction of all users that adopt/terminate the service in a time window
Rn(t) = Ra(t) − Rt(t)	net rate of adoption
empirical quantities
ta, tt	time of adoption/termination of service for a user
	lifetime of a user account in the service
Δt	time window used to define rates
I	number of Internet users in a country at the end of observation period
Na(t)	number of service users at time t
pa(t), pp(t)	rate of spontaneous/peer-pressure adoption at time t
,	rate of spontaneous/peer-pressure termination at time t
	rate of termination at time t
p(n)	probability that a user adopts, if a fraction n of its neighbours are adopters
prand(n)	value of p(n) after shuffling adoption times
Δp(n) = p(n) − prand(n)	unbiased measure of social influence in adoption
τ	inverse speed of innovation diffusion
model parameters
pa, pp	constant probability of spontaneous/peer-pressure adoption
ps, pr	constant probability of temporary/permanent termination
〈k〉	average degree of network
	peer-pressure adoption probability, weighted by degree
estimated parameters
	estimates of average degree and asymptotic rate of termination
	estimate of temporary termination probability