I'm not sure what data it is you're referring to. If they came in well below average, then they probably came into nursery mostly working within 22-36 months? Firstly, you need to show clear evidence of this attainment on entry and what percentage of children were working within this band. You then need to analyse the percentage of pupils who scored 6+ in the 13 areas and compare them with the national figures. This will tell you, and any inspectors how much progress they made in each area of learning. If you can also give a figure to the number of pupils who were at 3 points on entry to reception (3 points being about right for the start of reception) then this will help to track progress in nursery.