Class 13, October 15, 2015 Lessons 2.7 & 2.8

 By the end of this lesson, you should understand that: ◦ Each statistic—the mean, median, and mode—is a different summary of numerical data ◦ Conclusions derived from statistical summaries are subject to error ◦ Measures of central tendency can be used to make decisions

 By the end of this lesson, you should be able to: ◦ Make good decision using information about data ◦ Interpret the mean, median, or mode in terms of the context of the problem ◦ Match data sets with appropriate statistics

 Main idea: ◦ It is important to ask questions about quantitative information  Main idea: ◦ Additive change maintains absolute differences. Multiplicative change does not

 By the end of this lesson, you should understand: ◦ Ratios provide a way of measuring the relative increase or decrease of two variables ◦ Index numbers are a way of comparing the relative size of a variable over time

 By the end of this lesson, you should be able to: ◦ Calculate changes in the purchasing power of the minimum wage over time ◦ Use the Consumer Price Index (CPI) to compare the real cost of products at different times

 Main idea: ◦ Ratios (specifically in this lesson, percentages) are used for comparisons in a variety of contexts  The CPI is an example of an index number that is a percentage. (Not all index numbers are percentages.) This index is a percentage because it measures change relative to a base. Reflect upon the many forms and contexts in which comparisons have been made in this course.