研究生统计学课件--第2章描述统计学(E).ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 第2章 统计描述 * M F 0 EXP π A y2 π A ) ( x2 π A 1/x x→y n 2ndF π A DRG DRG F→E TAB DP OFF ON/C STATA hyp archyp sin Sin-1 cos Cos-1 tan Tan-1 CE n! AC π A DEG →DMS ln ex log 10x a →rθ b →xy → CPLX = x→M RM s ο M+ DATA 第2章 统计描述 * = x→M RM s ο M+ DATA 0 · ÷ +/- 5 1 8 4 7 6 8 3 2 × — + 第2章 统计描述 * M F 0 EXP π A y2 π A ) ( x2 π A 1/x x→y n 2ndF π A DRG DRG F→E TAB DP OFF ON/C STATA hyp archyp sin Sin-1 cos Cos-1 tan Tan-1 CE n! AC π A DEG →DMS ln ex log 10x a →rθ b →xy → CPLX = x→M RM s ο M+ DATA 第2章 统计描述 * Best Wishes to All of You! Thank You for Listening 结 束 语 * * * * * * * * * * * * * * * * * * * * * * * * * * * * 第2章 统计描述 * Inter-Quartile Range (IQR) （四分位数间距） P1 P25 P50 P75 P100 IQR=Q3-Q1 第2章 统计描述 * VARIANCE方差（mean square deviation均方差） The variance and its related measure,the standard deviation,are arguably the most important statistics. They are used to measure variability, but as you will discover they play a vital role in almost all statistical inference procedures. 第2章 统计描述 * The population variance总体方差 is represented表示 by σ2(Greek letter sigma squared). In both the population and sample variances样本方差 the numerator(分子) measures the sum of squared deviations from mean. The variance can be used to compare two sets of data; the larger the variance,the greater the spread.If measure units are hours, the variance units are hours2. Fortunately this problem can easily be remedied by creating another statistic,the standard deviation. 第2章 统计描述 * 总体方差 Population variance 样本方差 Sample variance ? ? 第2章 统计描述 * The standard deviation标准差 is the square root平方根 of the variance.The sample variance is showed by s2.The standard deviation by s. The standard deviation has two advantages over the varianc