Biology 2244A/B Lecture Notes - Lecture 2: Confounding, Interquartile Range, Statistical Inference
2 Jan 2017
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Individuals: objects described by a set of data. Variable: any characteristic of an individual: some variables place individuals into categories; others take numerical values. Important: do not confuse numerical summaries (average, count, proportion) with the variables themselves. Categorical variable: places individual into one of several groups/categories. Ordinal variables are not true quantitative variables because intervals between. Quantitative data can also be described as an interval or ratio consecutive ranks are often not identical: e. g. temperature is interval data makes sense to say that 20 degrees is 10 degrees more than. 10 degrees, but not to say that 20 degrees is t(cid:449)i(cid:272)e as (cid:862)hot(cid:863) as (cid:1005)(cid:1004) degrees: eg. Height can be both interval and ratio data makes sense to say that a 10ft tree is 5ft taller than a 5ft tree, and also that it is twice as tall as a 5ft tree. Symmetry: whether a histogram looks like a mirror image left to right.
