What does psychometrics study?

Psychometrics primarily focuses on the measurement of psychological variables such as intelligence, personality, and attitudes. It involves the development of theoretical and practical tools that quantify mental processes and behaviors. This field uses various statistical methods to analyze cognitive abilities and emotions.

The other choices pertain to distinct areas that do not relate to psychometrics. The study of the science of air and water at atmospheric conditions relates to thermodynamics and fluid mechanics, while mathematical calculations for heat of compression are associated with engineering and thermodynamic processes. Charts for heat absorption and release in refrigeration systems fall under thermodynamic analysis and refrigeration principles. Lastly, while the mental state of personnel could encompass an aspect of psychometric evaluation, the choice does not accurately capture the broader scope of psychometrics itself.