what is response theory in research what is irt what is itt why is it called item response theory what is irt? what is itt what is item response theory what is the purpose of the item response theory what is object response theory (irt) called which method is used to model a problem in a linear model what is itt? what is itt define it theory of continuous response what is itt why is itt called continuous response what is the itt theory what is the word word for continuous response? what is itt what is the itt in the study what is an item response concept