STAT 201 Chapter 2.1: Book Notes Chapter 2.1
19 Sep 2016
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For some characteristics, we usually see variability among subjects. Other characteristics vary by subject and across time: ex. Amount of time studying can vary by student and also by day. Variable= any characteristic observed in a study. Observations= data values we observe for a variable: can be a number or belong to a category. Categorical if each value belongs to a category. Quantitative if observations take on numerical values that represent different magnitudes: measure how much of something, zip code is numerical, but different zip codes aren"t of different magnitudes, so not quantitative. Key features of variables: quantitative- center and variability (aka spread, categorical- relative number of observations in different categories. Discrete= possible values from a set of separate numbers (0, 1, 2, 3, 4 ) Of discrete: number of pets, number of children: any variable phrased as the number of is discrete. Any variable with a finite number of possible values is discrete.
