MATH 10041 Chapter Notes - Chapter 3: Random Variable, Standard Deviation, Unimodality
12 Feb 2019
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3. 1: summaries for symmetric distributions: symmetric distributions are those in which the left-hand side of the graph of the distribution is roughly a mirror image of the right-hand side. Deviation: the distance each observation is from the mean. Standard deviation: a number that measures how far away the typical observation is from the mean: the standard deviation of a sample, a numerical summary, measures the spread of a distribution of a sample of data. It measures the typical distance of observations from the mean: to measure the amount. Variance: variance is the expectation of the squared deviation of a random variable from its mean. The empirical rule: if the distribution is unimodal and symmetric then: approx. 68% of the observations will be within one standard deviation of the mean: approx. 95% of the observations will be within two standard deviations of the mean: nearly all observations will be within two standard deviations of the mean.
