Data Visualization-Creating Multiple Line Graphs,8


the answer in 8. Deciding How to Present the Data separates the four U.S. populations in two different graph. can anyone explain what might be the reason for doing that, since this visualization can be improved by plotting each populations life expectancy over time on the same axis instead of on two separate ones.


Hi @zong. Good question. In this case I think it comes down to the question being asked, and the discretion/preference of the analyst. In this example we are only dealing with four separate groups, so it might work well to have all four plotted together on the same axis.

In the case of the answer code, separating the population into two groups by Race might make it easier for the reader to compare black and white Americans’ life expectancy because that is the focus of the separate plots. With this layout the reader can see that for each Sex, life expectancy for white Americans tends to be higher than that of black Americans.

With all four plotted together, the reader needs to decipher four distinct line-styles and then study the graph to determine which is which. This, arguably, could require more work from the reader. Ultimately, it comes to the question being asked and how the analyst speaks to the plot so in this case I think either approach could work.