Statistical Sciences 2244A/B Lecture Notes - Lecture 6: Probability Distribution, Standard Normal Deviate, Standard Deviation
12 Feb 2018
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Normal distributions sample space: interval of numbers density curves: models for continuous distributions; any curve has area exactly 1 underneath it, corresponding to total probability 1. It is always on or above the horizontal axis and describes the overall distribution pattern. Area under the curve and above any range of values on the horizontal axis is the proportion of all observations that fall in that range. No set of real data is exactly described by a density curve. Right-skewed: mean is greater than the median. Left-skewed: median is greater than the mean. Assign probability 0 to any individual outcome. Changing the mean without changing the standard deviation just changes the location of the curve but not the spread. Any particular normal distribution is completely speci c by its mean and standard deviation. Q-q plot: (quantile-quantile plot) compare observed quantiles from the sample to the expected quantiles if the the observations came from a normal population normal distribution (n()): 68-95-99. 7 rule.
