Psychometrics and Item Response Theory (IRT, Rasch)

Item quality, test reliability and fairness checks for exams and questionnaires

What you get:
- Basic: Classical item analysis (difficulty, discrimination); Reliability coefficients
- Standard: everything in Basic plus Rasch or 2PL model with item-fit statistics; Person-item map
- Premium: everything in Standard plus Differential item functioning (DIF); Revision advice per item and methods write-up

Scope limits:
- Basic: up to 30 items
- Standard: up to 60 items
- Premium: up to 120 items

What to provide when ordering:
- Response matrix (items by respondents)
- Test purpose and scoring key
- Group variables for DIF

Limits and responsibilities:
- All references, figures and facts must be verified by you before use
- Large data and heavy jobs must be run and verified on your own computer or server
- Remove personally identifying information from data before submitting
- Work beyond these limits or extra revisions is quoted separately

After ordering, submit the required details and files in the My Services section of your account. Delivery files appear there when the work is done, and you can request revisions if needed.

• Delivery on time
• Direct messaging
• Confidentiality assured