Table 1.

Summary of CCM results for whether influenza drives environmental variables, and vice versa, in different countries

			No. significant of 104		No. significant of 104 (lag test)
Flu surrogate	Environment surrogate	Log-flu	Flu → environment	Environment → flu	Flu → environment	Environment → flu
	X		14	27	8	14
X			53	14	25	6
X	X		56	22	27	10
	X	X	17	31	11	15
X		X	55	29	25	13
X	X	X	52	34	23	15

Tests used surrogates for influenza and/or environmental variables, and either untransformed or log-transformed influenza incidence. Results are shown with and without the requirement that the maximum cross-correlation occur in the correct temporal direction. Surrogates were constructed using splines, and analysis was restricted to periods when influenza was present. Numbers are out of a total of 104 tests (26 countries, four tests each).