CTT vs. IRT: What is the Difference?

QuantFish instructor Dr. Christian Geiser explains the key difference between classical test theory (CTT) and item response theory (IRT).
#Mplus #statistics #CTT #IRT #geiser #statisticstutorials #quantfish #mplusforbeginners #psychometrics
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[@haopakkeli6555]

Lang and Tay 2021 is a great summary for those who want to learn more.

[@Horangcha]

Great discussion! I just had to make the speed 1.25x😂

[@kesikisamuel4404]

You are spot on thank you

[@Dr.YusufShogbesan]

Great

[@preston748159263]

Could you help me understand how SEM is a different framework than IRT/CTT, or is SEM a subclass of IRT/CTT?

[@QuantFish]

SEM is the more general framework of latent variable modeling. Both IRT and CTT models are special cases of SEM. CTT models imply single-factor (and mostly restricted) confirmatory factor models. IRT models can be seen as special factor models where the link function between factors and their indicators (items) is based on logistic rather than linear regression.
Bengt Muthen's latent variable modeling framework and his Mplus software allow you to specify IRT & CTT models as special cases of factor (SEM) models.
Best, Christian Geiser