商务与经济统计 第14版 Ch02 Descriptive Statistics.ppt

Statistics for Business and Economics (14e)Metric VersionAnderson, Sweeney, Williams, Camm, Cochran, Fry, Ohlmann? 2020 Cengage Learning1 Chapter 2 - Descriptive Statistics: Tabular and Graphical Displays2.1 - Summarizing Data for a Categorical VariableCategorical data use labels or names to identify categories of like items.2.2 - Summarizing Data for a Quantitative VariableQuantitative data are numerical values that indicate how much or how many.2.3 - Summarizing Data for Two Variables Using Tables2.4 - Summarizing Data for Two Variables Using Graphical Displays2.5 - Data Visualization: Best Practices in Creating Effective Graphical Displays2 Summarizing Categorical DataFrequency DistributionRelative Frequency DistributionPercent Frequency DistributionBar ChartPie Chart3 Frequency DistributionA frequency distribution is a tabular summary of data showing the number (frequency) of observations in each of several non-overlapping categories or classes.Example: Marada InnGuests staying at the Marada Inn were asked to rate the quality of their accommodations as being excellent, above average, average, below average, or poor. RatingFrequencyPoor2Below Average3Average5Above Average9Excellent1Total204 Relative Frequency and Percent Frequency Distributions (1 of 2)The relative frequency of a class is the fraction or proportion of the total number of data items belonging to the class.The percent frequency of a class is the relative frequency multiplied by 100.Example: Marada InnRatingRelative FrequencyPercent FrequencyPoor 0.10 10%Below Average 0.15 15%Average 0.25 25%Above Average 0.45 45%Excellent 0.05 5%Total1.00100%5 Bar ChartA bar chart is a graphical display for depicting qualitative data.A frequency, relative frequency, or percent frequency scale can be used for the other axis (usually the vertical axis).Using a bar of fixed width drawn above each class label, we extend the height appropriately.The bars are separated to emphasize the fact that each cl