• Description, analysis, and interpretation of biomedical information are guided, in part, by the nature of the observations. Objects or events in categories, ie, nominal data, are simply counted. At a somewhat higher level, observations may have a "more than" character, so they can be ordered or ranked; the increments between the elements may be unknown or not measurable. Interval data have known and fixed increments, but no true zero; ratio scales are interval observations with a true zero. Some relationships between the levels of observation and the presentation and interpretation of biomedical information are discussed.
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