IRT analysis

Question 1

Item characteristic curve

Answer 1

You want to check whether an item can identify a characteristic.

The ICC provide info about the likelihood with whcih individuals of any trait level answer an item correctly.

Question 2

Item information

Answer 2

Items value at a particular theta level. You can calculate it by using the theta value to check the prob of answering correctly with that information value.

The higher the value, the greater the quality.

Question 3

Item information curve

Answer 3

By computing information values of a lot of trait (theta) levels, you cna make an IIC. It’s a curve for each item, based on those curves you can check how well the item fits

Question 4

Test information

Answer 4

Combined item info values obtain test info values.

For each trait level it has a test value

Question 5

Test information curve

Answer 5

Graph of all the test info, it illustrates the degree to whcih a test provides diff quality of information at diff trait levels.