Variables that differ based on quality (not quantity) and categorize people. Can be unrepresentative of differences and everyone else"s is very very small. Ex: grades on a midterm, finishing a race: you could be first in a class, but the differences between your grade. Equal intervals between variables but no absolute zero. Ex: weight, time, money in your bank account, kelvin. Qualitative, nonmetric, dichotomous (cid:523)it"s either one way or another(cid:524) Quantitative, metric, continuous: nominal, ordinal, interval, ratio. You want the most precise and effective form of measurement. Measurement determines the type of statistic that can be used. Ratio is most precise and offers most statistical possibilities. Is the measure fitting and suitable: you don"t use the same fitness test for 4 year olds and 98 year olds, don"t push people with parkinson"s who are predisposed to falling. )s the test doing what it"s supposed to do: 2 measurements: over.