Item Response Theory (IRT) has proven useful in physics education research to examine the validity of concept tests (e.g., Refs. 1-3) and online homework (e.g. Refs. 4-6), yet as a tool for the improvement of physics instruction (particularly exams), it is oftentimes perceived as a) mysterious, b) unjustified, and c) impractical. This article aims to debunk some of those prejudices and provide a quick-and-dirty guide; it does not do any justice to the associated psychometric theories (see for example the classic Ref. 7).

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