Chapter 1: Exploring Data Section 1: Displaying Data with Graphs

Variables Individuals Variables Categorical and quantitative

Pie Chart

Bar Graph

Graph Types

Dotplot

Dotplot with outliers removed

Histograms The following are ages in months of 15 AP Stat students

Histogram (zoom 9) See your neighbors

Histogram (Xmin at 189)

Things to look for Center Shape Spread Outliers Cautions: Pancake and skyscraper effect

Stemplots A stem consists of all but the rightmost digit. The leaf is the final digit. 1. Write the stems vertically, from smallest to largest. Draw a vertical line to separate the stems from the leaves. 2. Go through the data and write each leaf next to the appropriate stem. 3. Re-write the data, rearranging the leaves from smallest to largest. 4. You should indicate the units for the stems and leaves somewhere in the display.

Stemplots A stemplot is a sideways histogram. BUT, a stemplot contains the actual data. Sometimes it may be necessary to round data or split stems. For n>100, use a histogram. A back to back stemplot contains stems with leaves on both sides. This is useful to separate the data into two classes (boys and girls,...). Smaller leaves should be close to the stem.

Time Plots Place the time on the x axis. Time is the explanatory variable. Place the observations on the y axis. The observations represent the response variable.