The Global Gender Gap Report 2018 (GGGR), p. 5, Construction of the Index, § 2. Data truncation at equality benchmark: As a second step, these ratios are truncated at the "equality benchmark”. For all indicators, except the two health indicators, this equality benchmark is considered to be 1, meaning equal numbers of women and men. GGGR 2018, p. 42, Country Score Card: … To calculate the Index, all ratios were truncated at the parity benchmark of 1 and thus the highest score possible is 1.
Ricardo Hausmann; Laura D. Tyson; Saadia Zahidi, eds. (2012). The Global Gender Gap Report 2012(PDF) (Report). World Economic Forum, Geneva, Switzerland. Retrieved 2012-10-26.