统计学Lecture_2.pptx

Chapter 2, Part ADescriptive Statistics:Tabular and Graphical Presentations Summarizing Qualitative Data Summarizing Quantitative Data Summarizing Qualitative Data Frequency Distribution Relative Frequency Distribution Percent Frequency Distribution Bar Graphs Pie Charts A frequency distribution is a tabular summary of data showing the frequency (or number) of items in each of several non-overlapping classes. The objective is to provide insights about the data that cannot be quickly obtained by looking only at the original data. Frequency Distribution 频数分布：频数分布是一种数据的表格汇总，表示在几个互不重叠组别中的每一组项目的个数。 Example: Marada Inn Guests staying at Marada Inn were asked to rate the quality of their accommodations as being excellent, above average, average, below average, or poor. The ratings provided by a sample of 20 guests are: Below Average Above Average Above Average Average Above Average Average Above Average Average Above Average Below Average Poor Excellent Above Average Average Above Average Above Average Below Average Poor Above Average Average Frequency Distribution Poor Below Average Average Above Average Excellent 2 3 5 9 1 Total 20 Rating Frequency The relative frequency of a class is the fraction or proportion of the total number of data items belonging to the class. A relative frequency distribution is a tabular summary of a set of data showing the relative frequency for each class. Relative Frequency Distribution 相对频数：是所属组别的项目个数占总数的比例。 相对频数分布：是表示每一组的相对频数数据的表格汇总。 Percent Frequency Distribution The percent frequency of a class is the relative frequency multiplied by 100. A percent frequency distribution is a tabular summary of a set of data showing the percent frequency for each class. 百分数频数：百分比频数是相对频数乘以100。 百分数频数分布：是每一组的百分数频数数据的表格汇总。 Relative Frequency andPercent Frequency Distributions Poor Below Average Average Above Average Excellent