3.3 Test information by ability

The sum of the item information at each point of the \(D\)-score scale holds the test information for the ability. Figure 3.5 shows the test information for the first set of items. This shows a uniform level of information over the \(D\)-score scale.

The test information for the second set of items is extremely high at 33\(D\). Between a \(D\) of 40 and 50 there is no information in the test and at 65\(D\) there is another peak in information. This shows that the test information for the second set of items is not evenly distributed over the \(D\)-score range.

Figure 3.5: (fig:testinfo1)

Figure 3.6: (fig:testinfo2)