How to build graphs, charts and plots

For Categorical data

• If the data is nominal, then:• Few values: Pie

Chart• Many Values:

Pareto Chart (order of bars determined by frequency)

• If the data is ordinal, then:• Bar Graph (order

of bars determined by order of the ranking variable)

For Numerical Data

• Value classes are contiguous intervals that cover all possible data values

• Frequency counts can be made one class at a time (non-cumulative), or one more class every row (cumulative).

• Frequency counts can also be absolute or relative

Graphs for numerical data

Graph HorizontalAxis

Vertical Axis

HistogramBar Graph

Class Midpoints

Non-cumulative Frequency

F or %

PolygonLine Chart

Class Midpoints

Non-cumulative Frequency

F or %

OgiveLine Chart

Upper Class Limits

Cumulative Frequency

F or %

Other graphs for numerical data

• Time Series plot• Use the scatter plot graph type from

Excel’s Chart wizard

• Stem-Leaf plot• PhStat • Descriptive Statistics• Stem-Leaf Plot …

Other graphs for numerical data

• Run Chart• Use the scatter plot graph type from

Excel’s Chart wizard

• Box-Whisker plot (chapter 3)• PhStat • Descriptive Statistics• Box-Whisker Plot …

Histogram and Polygons in PhStat

• To let PhStat graph frequency distributions of the data use the command sequence:→PhStat

→Descriptive Statistics→Histogram & Polygons…

Histogram and Polygons in PhStat

• Then, you input the proper cell ranges in the dialog box for the procedure:• Variable cell range: range of cells for data.• Bins cell range: class limits for classifying

data into tables.• Midpoints cell range to then have PhStat

plot histograms and polygon charts of your choosing.

• Let’s draw the frequency distribution charts for 2.12 using PhStat in Excel during class …