Obtain the test characteristic curve for a test with ten items using the following item difficulty parameters:

b1 D 0:8 b2 D 0:5 b3 D 0:5 b4 D 0:0 b5 D 0:0 b6 D 0:0 b7 D 0:5 b8 D 0:5 b9 D 0:5 b10 D 0:8 The test characteristic curve has a well-defined S-shape much like an item characteristic curve. Only the section near an ability level of zero is linear. The mid true score of 5 corresponds to an ability score of 0:5.