ECO220Y1 Lecture Notes - Lecture 2: Multimodal Distribution, Bar Chart, Unimodality
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ECO220Y1 Full Course Notes
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Document Summary
Like a bar chart, except bars are connected. Range of data divided into non-overlapping and equal width bins. Each bar represents a bin (a group of values) Generally, number of bins corresponds to log2n, where n is the number of observations. Graphically describes how single variable containing interval data is distributed. Gives overview of variable with a single picture. Can make informed inferences about shape of population. Frequency histogram: bar height is number of observations in bin. Relative frequency histogram: bar height is fraction of observations in bin. Density histogram: bar area measures fraction of observations in bin. Sturges formula: number of bins = 1 + 3. 3 log (n) Use stems (first digit) to name bins, use next digit of number to make leaves. Perfect bell curves do not exist in real life. Mode is applied to histogram (most frequently occurring bin) instead of to raw data. Skewed if one tail stretches farther than the other.
