©Cynthia Krebs, ISYS 3270 ©Cynthia Krebs, ISYS 3270 Understanding Charts and Graphs

“Empowered as the new gods of cyberspace, we have been granted the ability to devour megabytes of data at a single gulp, digest it in mere microseconds and spew it forth without further thought as visually stunning color imagery. Gerald E. Jones, How to Lie with Charts

Charts display facts or numerical information in an organized way. Flowcharts, maps, lists, and diagrams are examples of charts. Graphs use numerical information to show relationships, comparisons, or change. The terms charts and graphs are interchangeable. What are charts and graphs?

Benefits of Charts and Graphs Data is more understandable Information is summarized Trends become apparent Numeric relationships are clarified Data is more understandable Information is summarized Trends become apparent Numeric relationships are clarified A picture is worth a thousand words!

Creating a Chart Involves: Examining the data Defining the purpose Choosing the right chart type Entering the data or importing it from other applications Editing the chart data

Examining the Data What type of information are you trying to illustrate? What message do you want to emphasize? Will a chart/graph clarify or cloud your message? Ask:

Basic Chart Elements Title X-Axis Label X-Axis Y-Axis Label Legend

Additional Chart Elements Scale Tick marks Gridlines Data labels Series

Defining Your Purpose What are the variables? Can you make comparisons? Are you showing change over time? Does one event predict another? Is there a relationship in the data?

Choosing the Chart Type Grow, decline, trends Line charts, column charts Ranks or compares Bar charts Percentage, portion, share Pie charts Look for key words:

Tables Show exact numbers or text Arrange data in columns and rows Display data in a small space

Lodging Comparison Lodging# RoomsDiningPoolPets Sleep’n Inn 30   Super 6119  Best Motel133   Valley View200  Use color in a cell, row, or column for emphasis

Column Graphs Show trends or changes over time Display limited number of data points Arrange time data chronologically left to right

Line Graphs Show trends or changes over time Show forecasts and projections Detail many data points Connect data point with trend lines

Area Graphs Show the magnitude of trends or changes over time Display the area below the plot line as a solid object May hide data

Pictographs Illustrate concepts only Use pictures or symbols instead of bars Select pictures that suggest graph subject Shows comparisons

Pie Charts Compare relative parts to the whole Display as a circle broken into segments

Donut Charts Compare the percentages of several different series Resemble a set of concentric, hollowed-out pie charts

XY or Scatter Graphs Compare pairs of values, shows relationships Use two coordinates for each point Display patterns Discrete values where data points coincide along the X and Y axes

Surface Charts Show trends in values across two dimensions Display on a surface that rises and falls to emphasize peaks and valleys

Radar Charts Display data radiating from the center Compare trends and magnitudes relative to a center point

Bubble Charts Show the relationship of sets against time Compare three sets of values Display third value as size of bubble

Stock of Hi/Low/Close Charts Display daily high, low, open,and close values Use the ends of the vertical line to indicate the high and low values Use the horizontal lines to indicate the close values

Mixed Charts Combines two series types for the data.

Interpreting Charts and Graphs Read titles, labels, and legend Look at numerical values Study data Make comparisons Look for relationships Check for trends Draw conclusions Click for USA Today Snapshots

Data charts provide a visual interpretation of data so you can give your audience a clear picture of the point you are communicating.