STA2023 - Chapter 4a (Displaying Quantitative Data)
As mentioned in chapter 3, graphs can reveal important information that a numerical analysis may hide.
such, chapter 4 extends the concept of graphing data – this time for quantitative data.
This chapter also
begins the introduction of numerical analysis of data.
Recall that a quantitative variable can be measured
numerically, with units of measurement.
Histograms and Stemplots (stem-and-leaf displays) are common
graphical methods we will use for quantitative data.
We will be skipping dotplots – they are briefly
discussed on page 52 of the book (if interested).
see pages 49-50 for an example
Used for quantitative data only (not categorical data)
Both axes must be labeled (variable on x-axis, frequency or relative frequency on y-axis)
Must use consistent scaling on each axis (this results in bars of equal width)
No spaces/gaps between the bars (unlike bar charts)
Usually, any observation on the line between two bars goes into the upper bar (see box on page 49)
Can be made on a graphing calculator (change width of the bars by changing the Xscl)
Activity 1 (page 85, #54)
. magazine (www.inc.com) listed its choice “boomtowns” in the United States – larger cities
that are growing rapidly.
Here is the magazine’s top 20, along with their 1-year job growth percentages:
Las Vegas, NV
Fort Lauderdale, FL
West Palm Beach, FL
San Bernadino, CA
Salt Lake City, UT
Putnam County, NY
Northern Virginia, VA
Santa Ana, CA
Camden County, NJ
San Diego, CA
A. Use your graphing calculator to make a
of the given data.
* Click on STAT, click 1 for Edit (your calculator should show six lists: L1 through L6)