“We pledge that no one will be left behind” — this is what countries declared when adopting the 2030 Agenda for Sustainable Development. They vowed to reach the furthest behind first.

Members of minority groups are often disadvantaged and discriminated against; in short, they are often the furthest behind. But they are also poorly understood due to a lack of data. Leaving no-one behind means ensuring that data are gathered, so that policymakers know the size and nature of minority groups, such as gender minorities.

There have been very few attempts to estimate how many people identify as transgender in any UNECE country. One estimate, from the United States in 2016, puts the figure at around 0.6% of US adults, or around 1.4 million people. A very tentative estimate from the UK in 2018 suggests there might be 200-500 thousand people identifying as transgender. But these estimates are very approximate, because no clear methods yet exist to measure these groups.

The pressing need for statistical measurement of gender minorities was debated recently by the Bureau of the Conference of European Statisticians (CES), guided by an in-depth review of current practice conducted for UNECE by the statistical offices of Canada and the United Kingdom.

These two countries, along with a small number of other frontrunners—notably the United States, Australia and New Zealand—have already invested a great deal of effort in investigating the statistical needs and implications of the changing gender identity environment. This is a landscape that is constantly changing, often politically sensitive, and associated with very deeply-held viewpoints.

The in-depth review examines the range of social and legal forces that create a need for data on the gender minority population: those whose gender identity does not correspond to their sex given at birth. For instance, if a country alters its laws to allow people to legally change their sex or gender in official documents such as birth certificates or passports, this affects the data that statistical offices gather.

The review also explores user demand and possible practical uses for data on gender identity, and looks at the many challenges in gathering such data.

One obvious challenge is simply figuring out what we are trying to measure. Even an apparently simple word such as ‘gender’ is not used and understood in the same way by everyone. Many people use the terms sex and gender interchangeably. For the majority of people, for whom their gender matches their biological sex (a group referred to as the ‘cisgender’ population), this mixing of terms might not be a problem. But treating them as synonyms becomes problematic if we are talking about people who do not self-identify in a way that matches their biological sex at birth. If the two are different, statisticians have to ask which they really need to know. For health statistics, for example, biological sex would usually be the important variable, while for statistics about labour market discrimination, gender would be more relevant. To gather data on the size of the transgender or gender non-conforming population, it may be necessary to ask two questions, one about sex and one about gender, to pinpoint those where the two do not match.

Even after settling on concepts and terms, data gatherers need to decide how to word questions — and where to put those questions — so that they get the data they need. They must balance the need for correct and detailed information on gender identity with the overarching need to minimize the burden on all respondents, to protect privacy and confidentiality, and to avoid disrupting the collection of data from the cisgender majority.

Discussing these and many other challenges raised in the in-depth review, the CES bureau called for UNECE to coordinate among countries to ensure that the findings and experiences of the pioneer countries are shared, with a view to eventually providing guidance to help other countries embarking on the same journey. The Bureau recognized the difficulty of getting this right, but it remains indispensable to try, by engaging with the communities in question and listening to their needs and concerns, so that we get closer to fulfilling the promise of leaving no one behind.

The in-depth review paper is available at: http://www.unece.org/statistics/working-paper-series-on-statistics.html