Chapter 111 Displaying Distributions with Graphs

Chapter 112 Thought Question 1 Two internet providers are being compared in terms of how long it takes to download large media files. Over a two month period the download times of the same 100 media files (of a specified size) are recorded for each provider. What summary measures of these times for each provider would be necessary to make a useful comparison?

Chapter 113 Thought Question 2 From the roster of a professional football team, the salary of the starting quarterback is an “outlier.” What do you think this means? If the players’ ages were considered, would this same quarterback necessarily have a value that is an “outlier”? Explain.

Chapter 114 Turning Quantitative Data Into Information u Shape of the data u Center of the data u Spread of the data (Variability)

Chapter 115 Weight Data STAT 208 Class Survey -- Spring, Virginia Commonwealth University

Chapter 116 Stemplots (Stem-and-Leaf Plots) u For quantitative variables u Separate each observation into a stem (first part of the number) and a leaf (the remaining part of the number) u Write the stems in a vertical column; draw a vertical line to the right of the stems u Write each leaf in the row to the right of its stem; order leaves if desired

Chapter 117 Weight Data 1212

Chapter 118 Weight Data: Stemplot (Stem & Leaf Plot) Key 20 | 3 means 203 pounds Stems = 10’s Leaves = 1’s

Chapter 119 Weight Data: Stemplot (Stem & Leaf Plot) Key 20 | 3 means 203 pounds Stems = 10’s Leaves = 1’s

Chapter 1110 Weight Data: Frequency Table * Left endpoint is included in the group, right endpoint is not.

Chapter 1111 Weight Data: Histogram Weight * Left endpoint is included in the group, right endpoint is not.

Chapter 1112 Shape of the Data u Symmetric –bell shaped –other symmetric shapes u Asymmetric –skewed to the right –skewed to the left u Unimodal, bimodal

Chapter 1113 Symmetric Distributions Bell-Shaped

Chapter 1114 Symmetric Distributions Mound-Shaped

Chapter 1115 Symmetric Distributions Uniform

Chapter 1116 Asymmetric Distributions Skewed to the Left

Chapter 1117 Asymmetric Distributions Skewed to the Right

Chapter 1118 Outliers u Extreme values, far from the rest of the data. u May occur naturally u May occur due to error in recording u May occur due to error in measuring u Observational unit may be fundamentally different

Chapter 1119 Number of Books Read for Pleasure

Chapter 1120 Key Concepts u Displays (Stemplots & Histograms) u Graph Shapes –Symmetric –Skewed to the Right –Skewed to the Left u Outliers