Distribution of samples and sampling methods in the survey of opinions regarding GM plants and foods in China.

1 The Yellow River Basin, Yangtze River Basin and the Xinjiang region are the three largest cotton-producing areas in China. Farmers began planting Bt cotton in 1997–1998 in the Yellow River and Yangtze River Basins and approximately 5 years later in Xinjiang.2 The Chinese Academy of Sciences and Chinese Academy of Engineering consisted of 719 and 699 members in 2008, and 745 and 804 in 2014, respectively. The members represent the highest level of scientific and engineering technology research in China.3 These 18 provinces were included in the first sample of 25 provinces in 2007–2008. These provinces are typical representatives of the four administrative regions. The sampling locations in these 18 provinces were similar to the 2007–2008 sample, and the respondents in these areas increased in 2007–2008.Data are from the study survey.