An error bar chart

Before running the analysis of variance, you graph the means and standard errors.

  1. To create an error bar chart, from the menus choose:

    Graphs > Chart Builder...

  2. Select the Gallery tab, and select Bar from the list of chart types.
  3. Drag and drop the Simple Error Bar icon onto the canvas area.
  4. Drag and drop Score on training exam onto the y axis.
  5. Right-click Sales training group and select Nominal for the measurement level.
  6. Drag and drop Sales training group onto the x axis.
    Figure 1. Simple error bar in Chart Builder
    Simple error bar chart shown on the Chart Builder canvas
  7. Click the Element Properties tab.
  8. In the Error Bars Represent group, click Standard Error.
    Figure 2. Chart Builder, Element Properties
    Element Properties for a simple error bar chart in Chart Builder
  9. Click OK in the Chart Builder to create the error bar chart.
Figure 3. An error bar chart of performance scores by training group
An error bar chart of performance scores by training group

Average performance clearly increases with added training days, but variation in performance decreases at the same time. ANOVA assumes equality of variance across groups; that assumption may not hold for these data.

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