Terminology : charts, graphs, plots, tables, diagrams


The physiognomy of a chart.

By physiognomy we mean the appearance of the chart. In order to know how to adjust and fine tune the graphic presentation of data we need to know what the different graphical components are called. This will vary from application to application. These terms apply to Microsoft Office chart tools.

  • Ten components of a generic chart.
    • Chart area and plot area.
    • Chart title, axis titles, legend, data labels, axis labels.
    • Tick marks and grid lines.
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  • In addition to these
    • Plot fill and border
    • Chart fill and border
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Excel: the anatomy of a chart

By anatomy we mean what's behind the scenes. The first thing is the data range being visualized. This is called the data range. A data range is named with the coordinates of its upper left and lower right cells. Here we have the range A1:C9. Note that for charts we generally include the column heading cells.

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This data range contains three columns. The "cases" are in rows and the variables in columns — each "case" is a range of age. Make sure you understand what that means before continuing.

The data set contains two data series — column B is count of women in each age category and column C is a count of men in each age category.

To create a chart

  1. Select the data range
  2. Insert…
  3. Chart type
  4. Chart subtype
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Now we can look at the guts of the chart. Point at the chart and right click to bring up the context menu and then click"Select Data."

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This brings up the "Select Data Source" dialog box. It has three parts. The top field shows the data range for this chart. Note that the name of the worksheet is incorporated into the name of the range followed by an exclamation point.

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On the lower right is a list of the data series in this chart. In this case we have two. Excel is clever enough to have used the column headings to name the series.

Finally, on the right we have information about the horizontal dimension (aka "X axis" or "category axis") of this chart.

The data series box gives us three options: we can add another data series, edit one of the existing data series, or delete a data series.

We'll select the female data series and then click on edit.

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In this dialog box we see the components of this data series — there are two: the name of the series and the data values. We can see where "female" came from as the data series name — cell B1.

Now we click in the Series Values box and note that the data range is highlighted in the worksheet.

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We won't make any changes. Just click OK until we get back to the chart itself.

Now use the mouse to click on one of the bars for male to select this data series. Then, right click and select "Edit Data Series."

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The Format Data Series dialog box allows us to tweak a number of things; here we will mention only two: series overlap and gap width. The former refers to whether the bars representing different data series are separated by a gap, next to one another, or overlapping.

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IN GENERAL, non-overlapping and non-separated is best - it shows what data goes together so that the two dimensions (here sex and age) are easily visualized. Only add features like overlap when there is a compelling visual communication reason for doing so!

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Gap width is the space between bars in the chart. The default is 150% — one and a half times the bar width. It's frequently attractive to lower this somewhat to give the bars representing the data a little more visual gravity.

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Next we add chart and axis titles.

Then data labels.

Then tweak colors.

OK onto exercise 2.

School Data Project