168x Filetype PPTX File size 0.18 MB Source: www.uky.edu
Variables Individuals are the objects described by a set of data; may be people, animals or things Variable is any characteristic of an individual Statistical Data What purpose do the data have? Individuals – Describe? How many? Variables – How many? Definition? Unit of measurement? Types of Variables Categorical variable places an individual into one of several groups or categories Quantitative variable takes numerical values for which arithmetic operations make sense Distribution of a variable tells us what values it takes and how often it takes these values Exploratory Data Analysis Examine each variable by itself… then relationships among the variables Start with graphs… then add numerical summaries of specific aspects of the data Levels of Measurement Nominal Ordinal Interval Ratio It's important to recognize that there is a hierarchy implied in the level of measurement idea. At each level up the hierarchy, the current level includes all of the qualities of the one below it and adds something new. In general, it is desirable to have a higher level of measurement.
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