The geography and carbon footprint of mobile phone use in Cote d’Ivoire

EPJ Data Science

Table 1 Regression of call intensity versus population

Grid	Intensity	Small population		Large population
Grid	Intensity	a	95% CI	a	95% CI
5 km × 5 km	number of calls	0.05	[−0.04,0.13]	0.87	[0.70,1.03]
5 km × 5 km	duration of calls	0.06	[−0.02,0.14]	0.86	[0.70,1.02]
10 km × 10 km	number of calls	0.06	[−0.05,0.17]	1.00	[0.77,1.23]
10 km × 10 km	duration of calls	0.08	[−0.03,0.18]	1.01	[0.78,1.23]
20 km × 20 km	number of calls	0.27	[0.11,0.43]	1.24	[0.91,1.57]
20 km × 20 km	duration of calls	0.28	[0.12,0.43]	1.27	[0.93,1.60]

Results of regression to log(intensity)=a log(population)+b. The cutoff between small and large populations is 10,000 for the 5 km × 5 km grid, 20,000 for the 10 km × 10 km grid and 40,000 for the 20 km × 20 km grid. The cutoffs were chosen so that the number of data points in the large population regime are approximately equal (105, 74 and 80 respectively).