ECON 2B03 Lecture Notes - Lecture 3: Scatter Plot, Categorical Variable
12 Jan 2017
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Document Summary
Cross tabulations are tabular summaries for two variables. The other variable represented by column heads. Information for both variables entered in table cells. Cross tabulations is extremely useful in bivariate (two-variable) analysis. Core graphs: two-dimensional graphs, examples: histograms, scatter diagrams, etc. Specialty graphs: combine elements from core graphs to display data in unique ways, examples: bar graphs, pie charts, etc. 3d graphs: display data of 3 variables with height, width, and depth. Identifies upper and lower limits of data class: vertical axis. Shows number of observations in each class (absolute frequencies) Shows ratio of class frequency to class width (relative frequencies: rectangles. Represent corresponded class frequencies by are or by height (is all class intervals are alike) In r we use the hist () function (hist(,prob=true) for relative frequencies divided by the class width. Class mark = average of two class limits.
