STAT 263 Lecture 9: Chapter 4
22 May 2017
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Genetically we want lots of variability, but when it comes to manufacturing products, we want the smallest variability. Range: difference between the largest value and smallest value in a set of data. We use (n-1) to get rid of a bias in the sample because we are not looking at the entire population. Always state stdv. and variance to at least 3 sig figs. Sample standard deviation: s, the positive square root of the sample variance ((cid:3041)(cid:2879)(cid:2869)) where n is the size of our sample. Deviations from sample mean are (cid:3036) and deviations will always add up to 0. Population variance: (cid:2870)= ((cid:3051)(cid:3284)(cid:2879)(cid:3091)(cid:3365))(cid:3118) ((cid:3015)) of the data that must lie within k standard deviations of the mean is at least 1 (cid:2869)(cid:3038)(cid:3118) There are very few instances you will actually know n. Chebyshev"s theorem: for any set of data (population or sample) and any constant k > 1, the proportion.
