Table 2.

Pearson Correlation Between Weekly Google-Predicted and Observed Influenza Activity by Location in Latin America, 2011–2014, Using Original and Permuted Google Flu Trends Time Series Data

Location	Original Time Series Data			Permuted Data		AR(1) Modela
	r	95% CI	P Value	r	95% CI	r	95% CI
Argentina	0.61	.52–.69	<.001	0.5	.41–.62	0.95	.93–.96
Bolivia	0.19	.05–.31	.007	0.18	.12–.22	0.79	.73–.84
Brazil	0.34	.22–.46	<.001	0.28	.21–.34	0.71	.63–.77
Chile	0.59	.49–.67	<.001	0.46	.36–.60	0.92	.90–.94
Mexico	0.83	.79–.87	<.001	0.7	.59–.83	0.94	.92–.95
Paraguay	0.18	.04–.31	.01	0.05	−.11–.23	0.8	.75–.85
Peru
All Peru	0.24	.11–.36	<.001	0.25	.22–.29	0.76	.69–.81
Limab	0.23	.09–.36	.002	0.23	.04–.43	0.68	.59–.75
Cuzcob	0.22	.08–.36	.002	0.32	.15–.44	0.79	.74–.85
Uruguay	0.65	.56–.73	<.001	0.56	.45–.65	0.66	.57–.74

Pearson correlation between weekly influenza activity predicted by an AR1 model, and observed influenza activity are shown for comparison. Observed influenza activity determined by weekly influenza-test positivity proportion from FluNet sentinel surveillance laboratories unless otherwise indicated. Weeks with zero sentinel surveillance specimens received for influenza testing coded as missing.

Abbreviation: CI, confidence interval.

^a Autoregressive model using the previous week's observed influenza activity as a predictor of the current week's.

^b Observed influenza activity determined by prospective community-based surveillance cohort, data available from 1 January 2011 to 26 July 2014.