4.1 Choosing a Chart Type

Learning Objectives

This section reviews the most commonly used Excel chart types. To demonstrate the variety of chart types available in Excel, it is necessary to use a variety of data sets. This is necessary not only to demonstrate the construction of charts but also to explain how to choose the right type of chart given your data and the idea you intend to communicate.

Choosing A Chart Type

Before we begin, let’s review a few key points you need to consider before creating any chart in Excel.

1. The first is identifying your idea or message. It is important to keep in mind that the primary purpose of a chart is to present quantitative information to an audience. Therefore, you must first decide what message or idea you wish to present. This is critical in helping you select specific data from a worksheet that will be used in a chart. Throughout this chapter, we will reinforce the intended message first before creating each chart.
2. The second key point is selecting the right chart type. The chart type you select will depend on the data you have and the message you intend to communicate.
3. The third key point is identifying the values that should appear on the X and Y axes. One of the ways to identify which values belong on the X and Y axes is to sketch the chart on paper first. If you can visualize what your chart is supposed to look like, you will have an easier time selecting information correctly and using Excel to construct an effective chart that accurately communicates your message. Table 4.1 “Key Steps Before Constructing an Excel Chart” provides a brief summary of these points.

Integrity Check

Carefully Select Data When Creating a Chart

Just because you have data in a worksheet does not mean it must all be placed onto a chart. When creating a chart, it is common for only specific data points to be used. To determine what data should be used when creating a chart, you must first identify the message or idea that you want to communicate to an audience.

Table 4.1 Key Steps before Constructing an Excel Chart

TIMETime SERIESSeries TREND:Trend: LINELine CHARTChart 1

The first chart we will demonstrate is a line chart. Figure 4.1 shows part of the data that will be used to create two line charts. This chart will show the trend of the NASDAQ stock index.

Read more: http://www.investopedia.com/terms/n/nasdaq.asp

This chart will be used to communicate a simple message: to show how the index has performed over a two-year period. We can use this chart in a presentation to show whether stock prices have been increasing, decreasing, or remaining constant over the designated period of time.

Before we create the line chart, it is important to identify why it is an appropriate chart type given the message we wish to communicate and the data we have. When presenting the trend for any data over a designated period of time, the most commonly used chart types are the line chart and the column chart. With the column chart, you are limited to a certain number of bars or data points. As shown below in Figure 4.1,  as the number of bars increases on a column chart, it becomes increasingly difficult to read.  In our first example, there are 24 points of data used to construct the chart. This is generally too many data points to put on a column chart, which is why we are using a line chart.

The following steps explain how to construct this chart:

Download Data file: CH4 Data

 1.  Open data file CH4 Data and save a file to your computer as CH4 Charting.

 2.  Navigate to the Stock Trend worksheet.

 3.  Highlight the range B4:C28 on the Stock Trend worksheet. (Note – you have selected a label in the first row and more labels in column B. Watch where they show up in your completed chart.)

 4.  Click the Insert tab of the ribbon.

 5.  Click the Line button in the Charts group of commands. Click the first option from the list, which is a basic 2D Line Chart (see Figure 4.2). Notice Excel adds, or embeds, the line chart into the worksheet.

Figure 4.2 Selecting the Basic Line Chart

Why?

Line Chart vs. Column Chart

We can use both a line chart and a column chart to illustrate a trend over time. However, a line chart is far more effective when there are many periods of time being measured. For example, if we are measuring fifty-two weeks, a column chart would require fifty-two bars. A general rule of thumb is to use a column chart when twenty bars or less are required. A column chart becomes difficult to read as the number of bars exceeds twenty.

Figure 4.3 shows the embedded line chart in the Stock Trend worksheet. Do you see where your labels showed up on the chart?

Notice that additional tabs, or contextual tabs, are added to the ribbon. We will demonstrate the commands in these tabs throughout this chapter. These tabs appear only when the chart is activated.

As shown in Figure 4.3, the embedded chart is not placed in an ideal location on the worksheet since it is covering several cell locations that contain data. The following steps demonstrate common adjustments that are made when working with embedded charts:

  1. Moving a chart: Click and drag the upper left corner of the chart to the corner of cell B30.

Note: Keep an eye on your pointer. It will change into when you are in the right place to move your chart.

 2.  Resizing a chart: Place the mouse pointer over the bottom lower corner sizing handle, drag and drop to approximately the end of Column I, and Row 45.

Note: keep an eye on your pointer. It will change into when you are in the right place to resize your chart

 3.  Adjusting the chart title: Click the chart title once. Then click in front of the first letter. You should see a blinking cursor in front of the letter. This allows you to modify the title of the chart.

 4.  Type the following in front of the first letter in the chart title: May 2014-2016 Trend for NASDAQ Sales.

 5.  Click anywhere outside of the chart to deactivate it.

 6.  Save your work.

Figure 4.4 shows the line chart after it is moved and resized. Notice that the sizing handles do not appear around the perimeter of the chart. This is because the chart has been deactivated. To activate the chart, click anywhere inside the chart perimeter.

Integrity Check

When using line charts in Excel, keep in mind that anything placed on the X-axis is considered a descriptive label, not a numeric value. This is an example of a category axis. This is important because there will never be a change in the spacing of any items placed on the X-axis of a line chart. If you need to create a chart using numeric data on the category axis, you will have to modify the chart. We will do that later in the chapter.

Skill Refresher

Inserting a Line Chart

ADJUSTING THE Y-AXIS SCALE

After creating an Excel chart, you may find it necessary to adjust the scale of the Y-axis. Excel automatically sets the maximum value for the Y-axis based on the data used to create the chart. The minimum value is usually set to zero. That is usually a good thing. However, depending on the data you are using to create the chart, setting the minimum value to zero can substantially minimize the graphical presentation of a trend. For example, the trend shown in Figure 4.4 appears to be increasing slightly in recent months. The presentation of this trend can be improved if the minimum value started at 500,000. The following steps explain how to make this adjustment to the Y-axis:

 1.  Click anywhere on the Y (value or vertical) axis on the May 2014-2016 Trend for NASDAQ Sales Volume line chart (Stock Trend worksheet).

 2.  Right Click and select Format Axis. The Format Axis Pane should appear, as shown in Figure 4.5.

   Mac Users: Hold down the Control key and click the Y axis. Then choose Format Axis.

 3.  In the Format Axis Pane, click the input box for the “Minimum” axis option and delete the zero. Then type the number 500000 and hit Enter. As soon as you make this change, the Y axis on the chart adjusts.

 4.  Click the X in the upper right corner of the Format Axis pane to close it.

 5.  Save your work.

Figure 4.6 shows the change in the presentation of the trend line. Notice that with the Y axis starting at 500,000, the trend for the NASDAQ is more pronounced. This adjustment makes it easier for the audience to see the magnitude of the trend.

Skill Refresher

Adjusting the Y-Axis Scale

TREND COMPARISONS: LINE CHART 2

We will now create a second line chart using the data in the Stock Trend worksheet. The purpose of this chart is to compare two trends: the change in volume for the NASDAQ and the change in the Closing price.

Before creating the chart to compare the NASDAQ volume and sales price, it is important to review the data in the range B4:D28 on the Stock Trend worksheet. We cannot use the volume of sales and the closing price because the values are not comparable. That is, the closing price is in a range of $45.00 to $115.00, but the data for the volume of Sales is in a range of 684,000 to 3,711,000. If we used these values – without making changes to the chart — we would not be able to see the closing price at all.

The construction of this second line chart will be similar to the first line chart. The X axis will be the months in the range B4:D28.

1. Highlight the range B4:D28 on the Stock Trend worksheet.
2. Click the Insert tab of the ribbon.
3. Click the Line button in the Charts group of commands.
4. Click the first option from the list, which is a basic line chart.

Figure 4.6.5 shows the appearance of the line chart comparing both the volume and the closing price before it is moved and resized. Notice that the line for the closing price (Close) appears as a straight line at the bottom of the chart.

1.  Move the chart so the upper left corner is in the middle of cell M1.

2.  Resize the chart, using the resizing handle so the graph is approximately in the area of M1:U13.

3.  Click in the text box that says “Chart Title.” Delete the text and replace it with the following: 24 Month Trend Comparison.

4.  Adjust the Closing Price axis, by double-clicking the red line across the bottom of the chart that represents the Closing Price.

5.  The Format Data Series dialogue box opens. In the Series Options, select Secondary Axis.

Excel adds the secondary axis.  Format the values on the secondary axis to represent prices.

 1.  Double click the Secondary Vertical Axis. (The vertical axis on the right that goes from 0 to 140.)

 2.  In axis options, scroll down to the Number section.

 Mac Users: If needed, click the Number “expand arrow” 

 3. Use the Symbol list box to add the $.

 4.  Press the Close button to close the Format Axis pane.

 5. Save your work.

Skill Refresher

X and Y-Axis Number Formats

Frequency Distribution: Column Chart 1

A column chart is commonly used to show trends over time, as long as the data are limited to approximately twenty points or less. A common use for column charts is frequency distributions. A frequency distribution shows the number of occurrences by established categories.

For example, a common frequency distribution used in most academic institutions is a grade distribution. A grade distribution shows the number of students that achieve each level of a typical grading scale (A, A−, B+, B, etc.). The Grade Distribution worksheet contains final grades for some hypothetical Excel classes.

To show the grade frequency distribution for all the Excel classes in that year, the Numbers of Students appear on the Y-axis and the Grade Categories appear on the X-axis. In this situation, notice we do not select the Total row.  The totals are a representation of all data and would skew the graph. Essentially you would be graphing the information twice.  If you want to display the totals in a chart, the best approach is to create a separate chart that only displays the total values.

The following steps to create the column chart:

 1.  Select the Grade Distribution worksheet.

 2.  In Row3, replace the red text at states [Insert Current Year] and replace it with the actual current academic term and year.

 3.  Select two non-adjacent columns by selecting A3:A8.

 4.  Press, and hold down the Crtl key.

 Mac Users: Hold down the Command key instead.

 5. Without letting go of the Ctrl key, select C3:C8

 6. From the ribbon click the Insert tab. Choose the Column button.

 7. Select the Clustered Column format. (First option listed.)

 8. Click and drag the chart so the upper left corner is in the middle of cell H2.  Resize the graph to fit in the area of H2: O13.

 9. Click any cell location on the Grade Distribution worksheet to deactivate the chart.

 10. Save your work.

Figure 4.10 shows the completed grade frequency distribution chart. By looking at the chart, you can immediately see that the greatest number of students earned a final grade in the B+ to B− range.

Why?

Column Chart vs. Bar Chart

When using charts to show frequency distributions, the difference between a column chart and a bar chart is really a matter of preference. Both are very effective in showing frequency distributions. However, if you are showing a trend over a period of time, a column chart is preferred over a bar chart. This is because a period of time is typically shown horizontally, with the oldest date on the far left and the newest date on the far right. Therefore, the descriptive categories for the chart would have to fall on the horizontal – or category axis, which is the configuration of a column chart. On a bar chart, the descriptive categories are displayed on the vertical axis.

CREATING A CHART SHEET

Figure 4.11 Move Chart

Figure 4.12 shows the Final Grades for all the Excel Classes column chart is in a separate chart sheet. Notice the new worksheet tab added to the workbook matches the New sheet name entered into the Move Chart dialog box. Since the chart is moved to a separate chart sheet, it no longer is displayed in the Grade Distribution worksheet.

Frequency Comparison: Column Chart 2

We will create a second column chart to show a comparison between two frequency distributions. Column B on the Grade Distribution worksheet contains data showing the number of students who received grades within each category for the  Current Excel Class Class. We will use a column chart to compare the grade distribution for the current class (Column B) with the overall grade distribution for Excel courses for the whole year (Column C).

However, since the number of students in the term is significantly different from the total number of students in the year, we must calculate percentages in order to make an effective comparison. The following steps explain how to calculate the percentages:

 1.  Highlight the range B4:C9 on the Grade Distribution worksheet.

 2.  Click the AutoSum button in the Editing group of commands on the Home tab of the ribbon. This automatically sums the values in the selected range.

 3.  Select cell E4. Enter a formula that divides the value in cell B4 by the total in cell B9. Add an absolute reference to cell B9 in the formula =B4/$B$9.  Autofill the formula down to cell E8.

 4.  Select cell F4 . Enter a formula that divides the value in cell C4 by the total in cell C9. Add an absolute reference to cell C9 in the formula =C4/$C$9.

 5.  Autofill the down to F8.

 6.  Select A3:A8, press and hold down the Ctrl key and select E3:F8.

 Mac Users: Hold down the Command key

 7.  Click the Insert tab of the ribbon.

 8.  Select the Column button.  Select the first option from the drop-down list of chart formats, which is the Clustered Column.

 9.  Click and drag the chart so the upper left corner is in the middle of cell H2.

 10.  Resize the chart to the approximate area of H2:N12.

 11.  Change the chart title to Grade Distribution Comparison. If you do not have a chart title, you can add one. On the Design tab, select Add Chart Element. Find the Chart Title. Select the Above Chart option from the drop-down list.

 12.  Save your work.