7.3 Country-level estimations
Using the definition from the previous section, we can calculate the percentage of children that are developmentally on track. Table 7.1 summarises this statistic by country. At a cut-off value of -2 SD, we expect that about 97.7% of the children will be on track. The actual country estimates fall into the range 93.9 - 99.9 and are thus near the theoretical value. This close correspondence shows that the definition and estimation procedure work as expected.
Bear in mind that the measurements leading up to these estimates come from different instruments. It is gratifying to see how well we can do with historical data, thanks to the robust underlying measurement model. Of course, comparability only gets better if all countries would use the same instrument. However, using the same tool everywhere is not a requirement.