3.4 Test information by age

Figure 3.7 shows the test information for the first set of items by age. This shows that this first set of items provides information over the entire age range (between 3 months and 36 months). The test information for the second set of items, shown in Figure 3.8, shows a high and small peak of information at 5 months. This means that the test is highly informative for 5 month-olds, but does not provide much information in the ages prior or after. Between 8 and 12 months there is a gap with no test information. For the second and third year, the test has information.

Figure 3.7: Test information by age for a set of 10 items evenly distributed over the \(D\)-score scale.

Figure 3.8: Test information by age for a set of 10 items not evenly distributed over the \(D\)-score scale.