For instance, knowing that a horse finished second is an ordinal datum. Notice that just knowing that second place finish does not tell you anything about how close or how distant that place was. Interval Interval data do provide information about the distance between data points. A scale is a very common way that social scientists provide interval data. Good physical examples are the common temperature scales, centigrade and fahrenheit.
All interval data assumes equal divisions between data points.
Note how the examples above do that. But, IQ tests and many other scales lose that property at their extremes. With interval data you may perform a wide variety of statistical tests including means, deviations, correlations, and tests of significance. Ratio Ratio data have equal distances between units and an absolute zero point that is not arbitrary. Experimenters select their IVs, hence their name.