PSY 295 Lecture Notes - Lecture 7: Level Of Measurement, Birth Order
Document Summary
Nominal scale: a set of categories that have different names. Measurements on a nominal scale label and categorize observations, but do not make any quantitative distinctions between observations. Ordinal scale: a set of categories that are organized in an ordered sequence. Measurements on an ordinal scale rank observations in terms of size or magnitude. First is better than second, but the scale has no information about how much better. Interval scale: ordered categories that are all intervals of exactly the same size. Equal differences between numbers on the scale reflect equal differences in magnitude. However, the zero point on an interval scale is arbitrary and does not indicate a zero amount of the variable being measured. The difference between 90 and 100 degrees is the same as the difference between 30 and 40 degrees. But zero degrees does not imply a lower bound. Ratio scale: an interval scale with the additional feature of an absolute zero point.
