Table 3.

Within countries comparison of male and female first authors, UK, USA, Australia, 1980, 1990, 2000, 2009

		Year
Country	1980	1990	2000	2009	P value for overall association	P value for trend	P value for 1990, 2000, 2009	P value for trend (1990, 2000, 2009)
UK
Male	35	93	127	200	<0.001	<0.001	<0.001	<0.001
Female	47	237	380	660
USA
Male	14	15	18	14	0.794	0.784	0.317	0.292
Female	109	194	186	214
Australia
Male		2	5	6			0.453	0.452
Female		6	29	34

P value for overall association was estimated using Chi-square test. Fisher's exact test was used where cell frequencies were <5

P value for trend over time was estimated using the Cochran-Armitage test