Sample interview questions: Have you worked with any item response theory (IRT) models, such as the three-parameter logistic model or the graded response model?
Sample answer:
Yes, I have extensive experience working with various Item Response Theory (IRT) models, including the three-parameter logistic model (3PLM) and the graded response model (GRM).
Three-Parameter Logistic Model (3PLM):
- Commonly used for dichotomously scored items (e.g., multiple-choice questions)
- Estimates three parameters: item difficulty (b), item discrimination (a), and lower asymptote (c)
- The lower asymptote represents the probability of answering the item correctly by chance
- 3PLM is suitable for items with varying levels of difficulty and discrimination
Graded Response Model (GRM):
- Used for items with multiple response options (e.g., Likert-type scales)
- Estimates a separate threshold parameter for each response category
- Assumes that the probability of selecting a response category is cumulative
- GRM is useful for measuring constructs with multiple levels of severity or intensity