Chapter 7 Model-data Fit Evaluation

To make valid inference, we need to assess whether model can fit data adequately. Model-data fit can be assessed at either test level or item level in either relative or absolute sense.

• Absolute fit

  • whether a set of models fits the data
  • whether a model fits the data of an item

• Relative fit

  • whether model A fits data better than model B for the whole test
  • whether model A fits data better than model B for an item