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Measures of Variation 方差：measures of variation or measures of spread 源于range发现range不足以评估整个set（因为只用到largest and smallest value），所以有了方差 The Sample Stand 阅读全文
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Measures of Center measures of central tendency:the center or most typical value:average Mean:its arithmetic average；受极值影响；可以通过去掉极值减少极值的影响 Median:the 阅读全文
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Distribution Shapes 由直方图到 smooth curve 1.this distribution of heights is bell shaped(or mound shaped), but the smooth curve makes seeing the shape a l 阅读全文
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2.3 Organizing Quantitative Data group quantitative data： To organize quantitative data, we first group the observations into classes (also known as c 阅读全文
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2.2Organizing Qualitative Data The number of times a particular distinct value occurs is called its frequency (or count) Relative-Frequency Distributi 阅读全文