This week there's plenty of talk about data. Tuesday 20 October marked World Statistics Day, Saturday 24 October is World Development Information Day, and on Friday 23 October "data visionary" Hans Rosling is giving ODI's data lecture.
So it seems timely to remind ourselves of some of the key issues relating to data and development.
There are huge gaps in what we know about people in many parts of the world - earlier this year the ODI reported that as many as 350 million people worldwide are not covered by household surveys. The absence of such large numbers of the poor and marginalised from national statistics does not just impede knowledge about progress towards ending poverty; it actually impedes tackling poverty.
These so-called "missing millions" include many of the communities with whom Health Poverty Action works in parts of Asia, Africa and Latin America. Communities on the margins - discriminated against, disenfranchised and often missing completely from the national picture of health and poverty.
Many of these communities are indigenous or ethnic minority groups. Data may not be collected centrally about them at all, or it may be collected at an aggregate level but not broken down by factors such as ethnicity which would reveal the inequities faced by such groups.
At the other end of the spectrum, we are in the midst of a global transformation in the amount of data being collected, its availability and use, including the emergence of big data and informal or publically owned sources of data. If these changes can be translated into better knowledge about the poorest and most marginalised people amongst a national population it could enable better targeted services and better outcomes for those groups.
But there are concerns about a potential 'dark side' of the data revolution. Access to vast amounts of information could aid powerful elites rather than the populations they are meant to serve. The need for a rights-based, participatory approach to data capture and use is critical to ensure data is used to challenge discrimination rather than reinforce it.
This picture of more and better data, but still vast gaps in knowledge and capacity, provides the backdrop to the Sustainable Development Goals, which were signed off in New York last month.
The SDGs encapsulate a commitment on the part of the international community to tackle global poverty and inequality sustainably, and specifically commit to 'leave no one behind.' This pledge relies profoundly on the 'data revolution' to ensure the poorest and most marginalised are counted. Indeed this is recognised by the SDGs through a target (number 17.18) to build countries' capacity to collect data and disaggregate it by a range of factors including income, gender, age, race, ethnicity, migratory status, disability and geographic status. The SDGs promise that the follow up and review processes will be informed by data which is disaggregated by these factors, as well as other relevant characteristics determined locally.
So far so good. And yet already the backtracking is clear. The next step for the SDGs is to agree a set of indicators by which to measure progress. But drafts of the indicator document seen by civil society groups show that governments are taking a "pick and mix" approach to data disaggregation, suggesting which goals should be broken down by which factors - and usually just choosing a couple.
Of course there are difficulties - huge ones - to overcome in building national statistical capacity around the world to make disaggregation of data by the full range of factors set out in the SDGs a reality. But if we start with such low aspirations before the Goals even come into force (on 1 January 2016) we set ourselves on a path to failure.
The Inter-agency and Expert Group on SDG Indicators meets from 26-28 October in Bangkok to review the list of indicators so far and discuss burning issues including data disaggregation. It must be ambitious.
The categories listed in Target 17.18 have been deliberately chosen, and agreed internationally, to reflect the most vulnerable groups of people in our world. If governments and inter-governmental bodies now choose exclude them, to not even try to track progress of all the SDGs for all of them, there is no way this new framework can fulfil its stated aim to leave no one behind.