STA 119 Lecture Notes - Lecture 4: Descriptive Statistics, Standard Deviation
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To calculate mean of data set, simply add up the data and divide by the number of data points. Symbol for mean of data set is x-bar. Doesn"t give much information about the variation (distribution) of data set. If there were no variation, everything would be the same. Without variation, everything in the population is the same and would would only need one piece of data. People are not all the same height. Patients with the same injury don"t recover at the same rate. When rolling 2 die, we don"t always get the same sum. An athlete doesn"t run a mile in the exact same time every day. The average deviation from the data mean. Use s (sample standard deviation) instead of (population standard deviation. The standard deviation divided by the mean that is turned into a percentage. Essentially comparing the sloppiness to what"s actual/exact.