The success or failure of the Sustainable Development Goals (SDGs) will depend, very largely, on sound statistics. It is obvious that we’ll need quality data to track progress towards the goals from their launch in 2015 to their 2030 deadline. But we’ll also need it throughout the journey to tell us whether we’re going the right way or need to change direction. We’ll need comparable data to show policymakers what is working (and what is not), to keep them motivated and, whenever necessary, to hold them to account.

When assessing whether children can read, we should remember why reading is so critical, and why we should be concerned when children miss out on this critical skill. Everyone reading this blog had a moment in childhood when meaningless swirls on a page began to make sense. As adults, our ability to read benefits us in a multitude of ways, every single day. There is no doubt that our lives would have been diminished and constrained without it.

The fourth Sustainable Development Goal (SDG) is not only about quality education – it is about inclusion and equity. These two words define the very substance of the quality education that we want for the world’s children. None of the targets related to SDG 4 can be achieved without them (indeed, target 4.5 is dedicated entirely to equity). So they have to be reflected in the indicators.

What a difference a year makes. Last week in Nairobi, when we woke to find a grey blanket of fog wrapped around our conference centre, it was hard to believe that only a year ago, the founding directors of our citizen-led assessment movement set up the People’s Action for Learning (PAL) Network. The Network is a south-south partnership whose member countries carry out sample-based, citizen-led assessments to measure the learning levels of all children in their own homes, regardless of their age, gender, or whether they go to school or not.

We have known for years that there are far too many primary-age children out of school: the stagnating numbers have been there for all to see. Far less has been known about the numbers of secondary-age adolescents and youth out of school, and in particular those of upper secondary school age who are – or should be – on the brink of a productive adult life. The numbers are out today, and they are every bit as alarming as we feared they would be.