This document discusses measurement and scaling techniques used in research. It defines measurement as observing and recording observations according to rules, while scaling is assigning objects to numbers or categories by rule. There are four levels of measurement: nominal, ordinal, interval, and ratio scales. Nominal scales use numbers as labels, ordinal scales show ranking, interval scales have equal distances between numbers, and ratio scales have a true zero point. Comparative scales like paired comparisons or ranking ask respondents to directly compare objects, while non-comparative scales like Likert or semantic differential scales rate single objects independently. The appropriate scale depends on the research problem and data type.