More Visual Displays of Data *** Calculator Skills List Operations and LINK command Section 1.1.2

Starter Here are dotplots of drive lengths (in yards) of two golfers. Write a paragraph that summarizes what you see.

Answer Both golfers average about 200 yards, but golfer A has a much bigger spread. His drives range from 160 yards to 240 yards, so his spread is 80 yards. Golfer B’s spread is from 190 yards to 210 yards, or 20 yards. So golfer B seems to be more consistent in his drives. The shape of both distributions appears uniform. In other words, for each golfer any one outcome is equally likely as any other to occur.

Today’s Objectives Create a manual stemplot of data. Create a manual timeplot of data. Link calculators to send and receive data. Create a calculator histogram and timeplot. California Standard 14.0 Students organize and describe distributions of data by using a number of different methods, including frequency tables, histograms, standard line graphs and bar graphs, stem-and-leaf displays, scatterplots, and box-and- whisker plots.

Creating a Manual Stemplot A stem-and-leaf plot is really just a sideways histogram. –The choice of stems is like choosing bar widths. –Leaves should be arranged from least to greatest on each line. That may mean doing the plot twice: a “draft” and final copy. –Don’t leave out a stem for lack of observations; it’s just like a histogram with a bar that has zero frequency. Look at the data on page 10: Percent of Population Over 65 by State: Create a stem-and-leaf plot of the data. –Data are rounded to 0.1, so use tenths as leaves and whole percents as stems. –Start by drawing your vertical line and filling in stems. Look for “split stems” and “back-to-back” stemplots in the reading and homework.

Percent of Population Over 65 by State Note: 4|9 = 4.9%

Creating a Timeplot A timeplot is just a way of representing changes in one variable over time. –So time becomes a second variable. Always put time on the horizontal axis and the measured variable on the vertical axis. Plot data points as ordered pairs. Connect the dots to form the timeplot.

Example 1.5 (page 21) Here are the data on the rate of deaths (per 100,000 people) from cancer in the U.S. from 1940 to Create a timeplot on paper of these data. –You may come get graph paper if you wish. Write a comment about any trend you see

Here’s the finished timeplot Note the steadily increasing trend of the data Write the trend in context: “In the years 1940 to 1990 the cancer death rate steadily increased from 120 per 100,000 to 200.”

Creating a List on the TI To see lists 1 – 3, tap STAT : Enter –If you see other lists, tap STAT : 5 –Now tap STAT : Enter and you should see lists. –If you don’t see lists 1 – 3, tap STAT : 5 Clear L 1 by putting the cursor at the very top of the column, then tap CLEAR:ENTER Enter the elements of your list at the cursor. –Enter a list now of any three numbers.

Link to Send or Receive Lists Receiving: –2 nd : LINK : Receive –Enter and wait for data –If need to, choose Override to accept –2 nd : Quit and disconnect at “Done” Sending: –2 nd : LINK : Send –Scroll to list(s) and Enter Note the marker by the chosen list name(s) –Right arrow to Transmit –Hit Enter AFTER partner shows “waiting” –2 nd : Quit and disconnect at “Done”

Renaming a List Link up and get L 1 from me now. We use L 1 – L 6 a lot, so give the data a unique name to save them for later use. Enter this command: L 1 → PCT65 –In this case, right arrow means use the “store” key, called STO→, above the ON key. –Use the ALPHA function to get the letters PCT. You now have two copies of the data. –Changing one does not change the other.

Sorting a List Sorting allows you to easily see the minimum and maximum of a list, and to find the median by counting. Sorting also makes creating stemplots easier. Enter this command: STAT : SortA(L 1 ) Look at L 1 now by entering STAT : Edit –You will see the data arranged from least to greatest.

Drawing a Histogram on the TI Here are commands to display a histogram: 1.2 nd : STAT PLOT : 1(chooses plot 1 of 3) 2.Turn it on by tapping ENTER 3.Choose Type: →→ENTER(chooses hist icon) 4.Make Xlist say L 1 5.Make Freq say 1 6.Tap ZOOM : 9 to see the histogram

Modifying a TI Histogram In the histogram you did manually (reading, page 11) of age data, you used a class width of 1% with a minimum of 4% and maximum of 19%. Let’s do it on the TI Tap WINDOW and set –Xmin=4 –Xmax=19 –Xscl=1 Tap GRAPH to see the histogram –How does it compare with the stemplot we did?

Percent of Population Over 65 by State Note: 4|9 = 4.9%

Creating a Timeplot on TI Clear L 1 with these commands –STAT : Edit : ↑(L 1 should be highlighted) –CLEAR : ENTER(L 1 should now be empty) Clear L 2 in the same manner Enter the years in L 1 and the death rates in L 2 –U.S. cancer death rates by year per 100,000 population (Example 1.5, page 21) Tap 2 nd : STAT PLOT : 1 and change Type to a broken- line graph (2 nd icon) Xlist still says L 1 ; make Ylist say L 2 Tap ZOOM 9 to see the graph

Today’s Objectives Create a manual stemplot of data. Create a manual timeplot of data. Link calculators to send and receive data. Create a calculator histogram and timeplot. California Standard 14.0 Students organize and describe distributions of data by using a number of different methods, including frequency tables, histograms, standard line graphs and bar graphs, stem-and-leaf displays, scatterplots, and box-and- whisker plots.

Homework Read pages Do problems 9 – 12 –Note: Problem 11 is based on pulse data we have not collected. Instead, use the data in Table 1.1 on page 10. Do a back-to-back stemplot using Alabama – Missouri as one data set and Montana – Wyoming as the other.