STATS 250 Lecture Notes - Lecture 1: Descriptive Statistics, Standard Deviation, Statistical Inference
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STATS 250 Full Course Notes
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Statistics numbers measured for a purpose collection of procedures/principles for gathering data and analyzing information in order to help people make decisions when faced with uncertainty help us make decisions. Sample data = subset of larger population -> use sample statistics to estimate population parameters. Describing a variable: categorical = groups *if there is order/ranking ordinal variable, quantitative (aka. Measurement or numerical) = numerical values: discrete, continuous. [ = includes number ( = does not include. Interpretation: shape (bell-shaped, uni-modal, symmetry, skew ) **bimodal could be 2 subset of population identify shape for both e. g. males & females. Standard deviation (use for reasonably symmetric sensitive to extreme observations) Standardized score = (cid:3042)(cid:3029)(cid:3046)(cid:3032)(cid:3045)(cid:3049)(cid:3032)(cid:3031) (cid:3049)(cid:3028)(cid:3039)(cid:3048)(cid:3032) (cid:3040)(cid:3032)(cid:3028)(cid:3041) (cid:3046)(cid:3047)(cid:3028)(cid:3041)(cid:3031)(cid:3028)(cid:3045)(cid:3031) (cid:3031)(cid:3032)(cid:3049)(cid:3028)(cid:3047)(cid:3042)(cid:3041) where n = size of pop. Variance = squared sd but units are also squared. For bell shaped curves 68% of values fall within 1 sd in either direction, 95% within 2 sd and 99. 7 in 3.
