Statistics 1770 Lecture : September 18.docx
Document Summary
Leaf: (usually) last digit: list stems vertically from smallest to largest including stems without leaves, attach each leaf to appropriate stem. Numerical summaries of quantitative data: measures of the centre, mean, the arithimetic average of all the data values, median, the middle value in the data (bigger than the observations and smaller than the observations, mode, the mode is used in two related contexts i) location of the peak in the distribution ii) the observation that occurs most often. Comparing mean, median: mean, uses eery observation, affected by skewness. outliers, nice statistical properties, median, ignore most observations, not generally affected by skewness. outliers, may not be useful if data concentrated on just few valus.
