Charts in EXCEL

Editor's Notes

• #3: Excel offers many chart type options, however there are four types that are most commonly used. Column / bar charts, Pie charts, Line charts, and Scatter charts. Column and Bar charts are the same except that the axes are flipped. In fact, Excel’s Column charts are what people typically call “Bar” charts. In this presentation I group them together as “Column / Bar”.
• #4: Column / Bar charts are use to represent numerical data for individual data points, data categories, or for time periods. The numerical data represents either a tally or a specific value. Observe the illustrated examples.
• #5: Pie charts display data as what proportion each item is to the whole. This can be shown as either a numerical value or as a percent. In this example The pie slices represent the portion of the class with the corresponding hair color.
• #6: Line charts can be used wherever column / bar charts are used. However, in many cases they are not as effective. Perhaps the best application of line charts is in showing numerical values for different time periods. In this example, US Population is plotted against the year for each ten year interval since 1900.
• #7: Scatter charts appear similar to line charts, but they are different. A scatter chart plots a relationship between two variables. Values on the Y axis (vertical) are a function of the variable numbers on the x axis (horizontal). The example shown plots measured plant growth in inches (Y axis) as a function of the number of hours per day that the plant received light (x axis). Both axes contain numerical values. By contrast, in a line chart (or bar chart) the X axis always represents a non-numerical value / description.
• #8: Let’s try this exercise. What chart should you use to plot these examples? The average height of a various tree types in North America? (Column/Bar) The monthly rainfall for 2009? (Line or Column/Bar) % of class who prefer pizza, hot dogs, burger, or salad for lunch? (Pie) Daily calorie consumption vs. weight? (Scatter)
• #9: Let’s create some charts. Let’s consider a simple example of class hair color. Here is the data. 16 students have brown hair; 4 have black hair; 6 have blonde; 1 has red; 1 has another color.
• #10: Type the data in EXCEL in 2 columns as shown – hair color in column 1, corresponding student count in column 2. To create a chart, you must first Select / Highlight the data. Second, Click INSERT from the menu bar and Select CHART. Alternately, you can select the Chart Button in the Standard Toolbar.
• #11: Select the appropriate chart type. Column type, which is the vertical bar chart is the default selection. There are 7 varieties of these. Since we only have one series of data, we are not interested in the composite (stacked) charts. We will select from the 3 choices in the first column. I will pick the 2-D chart. Click Next and Next again (step 2).
• #12: Type in your chart title. I leave the X axis label blank, since it is obvious from the data. I label the Y axis “number of students.” Click Finish.
• #13: The Key (labeled “Series 1”) is superfluous since we only have one series of data. Click on it and press Delete.
• #14: You can change colors and add fill effects to all or any of the bars, to the plot area, the chart area, and the gridlines. Click to select the bar(s) or area. Right click and select Format (Data Series, Data Point, Plot Area, Chart Area, or Gridlines). Here is an example of how to change a bar color. In this example I changed each bar color individually. Then I changed the color of the Plot Area. To review: Whatever area color you want to change, first select it, then right click and select Format from the popup menu.
• #15: You can also change the font face and color of any of he Text blocks in the chart, i.e., the Title, or axes labels. Highlight them and select a new text color or font type or size from the formatting toolbar. You can also edit the wording.
• #16: We have created a Column/Bar chart to depict our survey graphically. Are there other options that would work? Remember that we said you can always use a line chart wherever you can use a bar chart.
• #17: Let’s change it to a Line Chart. Click on “Chart” in the main menu and select Chart Type from the drop-down menu.
• #18: As with the bar charts, we only need look at the 3 choices in the left column. For line graphs, the middle choice is usually best, since it shows the line and the dots and is less confusing than the 3-D choice. You can change the color of the individual data points as well as their shape. Here is the resulting line graph.
• #19: Both graphs are satisfactory illustrations of the data. I feel the column/bar chart is more effective in this situation. It is more colorful and clear and there is really no reason to connect the discrete data points.
• #20: Let’s consider another example. The example is population growth in the US since 1900. Let’s plot Population over time.
• #21: We type the data in EXCEL in 2 columns as before – the year in column 1, the corresponding population in column 2. Include the column headings. Select / Highlight the data. Click on Insert / Chart. Then, let’s just click Finish.
• #22: Creating the 3 chart types from the population data yields interesting results. Both the bar and line charts generate two sets of data. This is because any column of numerical values is viewed as a series to plot. This is why for these types of charts the first column of data must be alphnumeric descriptions, not numbers. Since they were input as numbers, only the Scatter chart interprets the data properly.
• #23: To obtain a bar or line chart of the population data, we simply enter the years as non-numeric values. Reenter each year, placing an apostrophe before each number.
• #24: Now, take a look at the charts. When we enter the years as non-numeric fields, the column/bar and line charts are appropriate and the Scatter graph is not.
• #25: Let’s do one more example – a Pie chart. Let’s look back at the Class Hair Color data.
• #26: We select the data again as before and select a Pie chart. I like to stick with the 4 types in the first 2 columns. I’ll select the first choice and Finish. Take a look at the chart. It needs some formatting, don’t you think?
• #27: Let’s look at other formatting options that we have for a Pie Chart. Also since I neglected to give it a title, let’s do that now too. Click on the Chart, then select Chart / Chart Options.
• #28: We click on the Title tab to enter our title. Then we click on the Data Labels tab to check off whether we want the graph to display labels on the pie pieces – value, percentage, category name or any combination. After selecting our choices, we click OK. Let’s also change the colors of each piece in the same way we changed the bar colors in a past example.
• #29: Notice the charts with various data labels. When we check off that we’d like to view categories, then the key is not necessary, so it was deleted.