Nunnally Pdf | Psychometric Theory

A significant portion of the text is dedicated to Classical Test Theory (CTT). Nunnally decomposes an observed score ($X$) into two components: $$X = T + E$$ Where $T$ is the True Score and $E$ is the Error.

Nunnally defined psychometrics as the science of constructing models that link (like intelligence or anxiety) with observables (like test scores or survey responses). His work standardized how we determine if a test is actually measuring what it claims to measure. Core Pillars of Psychometric Theory psychometric theory nunnally pdf