Chapter 5 Create plots
5.1 Create a line chart
To create a plot of the logarithm of UK GDP, select the “year” and “lnGDPPC” column, go to “Insert” and click on “Recommended charts”. Select the plot which has “year” on x-axis and “lnGDPPC” on the y-axis among the options proposed.
Note: you may be tempted to select fancy layouts using the “Quick Layout” tab. Although it may be helpful in some cases, it is more likely to add unnecessary detail and therefore be more confusing to read. Better to invest in learning how the chart elements can be modified to serve the purpose of each individual graph.
5.2 Titles
To add or remove a char title, click on the chart and go to “Chart Design”, then “Add Chart Element”.
- Select “Chart title” to add or remove a plot title.
- Select “Axis Titles” to add titles to the horizontal and vertical axis.
Note: depending on the plot, adding titles may not add much information. For example, in the case of the plot of the logarithm of UK GDP per capita, adding axis titles do not add much information as it is clear already that the horizontal axis represents dates and the plot title already explains what it represents. In other cases, it may be impossible to understand what is represented without axis titles.
5.3 Format axes
Formatting axes properly may go a long way to produce a graph that is informative and immediately understandable.
- To format the horizontal axis: right click on the dates on the chart and select “Format axis”. To have the dates displayed only every 10 years, use the “Label” option.
- To format the vertical axis: right click on the vertical axis and select “Format axis”. To modify the range of the vertical axis so that it better fits the range in the data, change the minimum or the maximum in the “Bounds” tab. To reduce/increase the number of ticks, change “Major” in the “Units tab. To reduce the number of decimal points, go to the”Number” option and specify your preferred number of decimal points (eg 1).
5.4 Logarithimc (ratio) scale
Instead of plotting the logarithm of GDP per capita, you may want to represent GDP per capita on a ratio scale. Here is how the “Format axis” panel can be used to plot the logarithm base 2 of GDP per capita, so that each tick mark represents a doubling of GDP per capita.
5.5 Add trend lines
To add a trend line, click on the chart and go to “Chart Design” and “Add Chart Element”. Then go to “Trendline” and select the shape of trend line that is the most relevant for your plot (here a linear trend because we plot the logarithm of GDP).