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Unformatted text preview: Week 2: Probability Distributions ChE, BioE, EnvE 213 Prof. Milo Koretsky Population vs. Sample Population. Collection of all similar items about which we want to make a decision. Sample. The portion of a population or process that we actually measure. The smallest sample size is 1, the largest sample consists of the entire population (100% sample). Statistic. A summary value calculated from a sample of observations. Usually a statistic is an estimator of some population parameter. Random Sample. A sample selected from a population in which every sample had an equal chance of being selected. Usually we try to obtain random samples. Population Sample Mean μ x Standard deviation σ s Dirtribution Probability Distribution. A set of values (or ranges of values) with their corresponding probabilities that describe a population or a sample . There are three basic characteristics of a distribution: location (average), spread (deviation), shape. Attribute variable: Variables which take on discrete values (coin flips, gender, defects) Continuous variable. Variables which can take any, continuous numerical value such as temperature. Many phenomena with continuous variables follow a normal distribution. Say we have the following data (This is real data): ChE 312 Data Exam 1 94 Exam 1 95 86 90 84 90 50 89 84 89 50 74 55 73 87 83 63 80 100 88 38 89 88 88 43 93 83 67 84 82 63 62 65 80 55 74 79 67 100 43 62 70 63 64 70 55 30 50 75 41 60 66 71 37 81 60 67 64 85 64 58 71 56 13 50 44 63 65 68 63 64 62 80 48 58 93 Histograms.Histograms....
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This note was uploaded on 04/17/2010 for the course CHE 213 taught by Professor Staff during the Winter '08 term at Oregon State.
 Winter '08
 Staff

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