Sensitivity, specificity, and the agreement index

Teacher with students

What are they, and why do they matter when choosing a developmental screener?

The extent to which a test performs accurately in a screening situation can be determined by the three indices of a test’s validity: Sensitivity, Specificity, and the Agreement Index. Here’s a brief explanation of each and how they relate to a test’s validity:

  • Sensitivity relates to the proportion of the children at the extreme end of the continuum (Potential Delay category) who were identified as such in the screening process.
  • Specificity refers to the proportion of those children in the OK category who were identified as OK in the screening process.
  • Agreement Index refers to the percentage of children for whom the screening decision was correct, whether at the extreme or in the “OK” range.

These three indices are the best way to determine the extent to which a screening test is doing what it is supposed to do: separating children at the extreme end (potential learning delays) from children who perform in a more typical manner. Having these factors at play when identifying the children who may need further testing can help get them the support they need... sooner.

ESI-3 takes all three indices into account!

If you need to take a closer look at overall abilities to determine where additional support may be necessary, the Early Screening Inventory, Third Edition will give you the tools you need to individually screen kids ages 3:0–5:11 in several areas of development.  

Read the previous articles in this series.

For more information on developmental screening with the ESI-3, visit