Slides-02 - ECON1203/ECON2292 Business and Economic...

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Click to edit Master subtitle style ECON1203/ECON2292 Business and Economic Statistics Week 2
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22 Week 2 topics l Measures of central tendency or location l Measures of dispersion or spread l Measures of association l Introduction to linear regression l Key references l Keller Chapter 4, especially 4.1-4.4
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33 Numerical summaries of key features l Previously used graphical methods to summarize data l Can also use numerical summaries of sample or population data l Key features of a single variable l Location, spread, relative standing, skewness l Key feature of two variables l Measures of (linear) association
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Measures of location l A parameter describes key feature of a population l A statistic describes key feature of a sample l A natural measure of location is the arithmetic mean l Other variants l Weighted mean (WAM) l Geometric mean 44
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55 Measures of location… l Median is middle value of ordered observations l When n is odd median will be unique l When n is even average middle two values l Median depends on ranks of observations l Doubling largest observation will not change median
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66 Measures of location… l Mode is most frequently occurring value(s) l Modal class previously defined in context of unimodal histograms l Mean, median & mode all provide different notions of “representative” or “typical” central values l For quantitative data mode usually not a very useful measure of location l What about mean vs. median? Depends l For symmetric distributions mean=median l When positively (negatively) skewed mean > (<) median l Median may be preferred when outliers appear in data
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Outlier. ..s l A Malaysian man was speechless when he received a $218 trillion phone bill and was ordered to pay up within 10 days or face prosecution. .. It wasn't clear whether the bill was a mistake. .. Associated Press
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This note was uploaded on 07/28/2011 for the course ECON 1203 taught by Professor Denzilgfiebig during the Three '11 term at University of New South Wales.

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Slides-02 - ECON1203/ECON2292 Business and Economic...

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