Research+and+testing.

=Research and testing. = = =

Scales.
There are **__four types__** of [|data scale].
 * **Nominal scale.** || This classifies objects into discrete categories. Food, wood, plastic etc. These scales are very weak, they tell you no more than one object is different from another. ||
 * **Ordinal scale.** || Labels used in ordinal scales can be words, symbols, letters or numerals. When numerals are used they only show sequence. ||
 * **Interval scale.** || Interval scales are more powerful, the intervals between points on the scale are equal, measurements on this scale can be used for quantitive analysis. ||
 * **Ratio scale.** || The difference between a ratio scale and an interval scale is that the 0 on a ratio is an absolute O, (0 grams is an absolute 0) not something arbitrarily decided by commitee. ||
 * Nominal scale. || Ordinal scale. || Interval Scale. || Ratio scale. ||
 * [[image:http://faculty.washington.edu/chudler/gif/colscale.gif align="center"]] || [[image:http://faculty.washington.edu/chudler/gif/hotscale.jpg width="206" height="121" align="center"]] || [[image:http://faculty.washington.edu/chudler/gif/temscale.gif align="center"]] || [[image:http://faculty.washington.edu/chudler/gif/racscale.gif align="center"]] ||