1. Age is a ratio level variable. Age has a true zero point (birth represents "zero years"), and the differences between ages are equal. It is also meaningful to say that someone who is 40 is twice as old as someone who is 20. 2. Height is also a ratio level variable because it has a true zero point (zero height means the absence of height), and the numbers represent equal intervals. We can say someone is twice as tall as someone else, which is only possible with ratio data. For example, someone who is 180 cm is twice as tall as someone who is 90 cm. Therefore, height is measured at the ratio level. 3. Race is a nominal level variable because it represents categories with no numerical value or order. The categories cannot be ranked or meaningfully compared; the labels simply distinguish groups, and no category is higher or lower than another, so this variable is measured at the nominal level. 4. Number of Jobs You've Ever Had is ratio level. This variable is a count with a true zero point (zero jobs means the absence of jobs). The intervals are equal and ratios make sense, for example