1. Reference lines, trend lines, and forecasting
Let's end this chapter by looking at ways to take your visualization to the next level.
2. Enhancing your visualization
There are a couple of things you can do in Tableau to enhance your visualization. These include adding reference lines, trend lines, and forecasting. Let's take a closer look at each of these.
3. Reference lines
A reference line is simply a line that gets drawn on a chart representing another measure or point of reference. Reference lines can be useful in providing context. For example, a line showing the average will visually show the difference of each mark in the chart relative to the average.
4. Trend lines
Trend lines are used to predict the continuation of a certain trend. As you can see in the slide, adding a trendline makes it easy to see that overall this measure is decreasing. Tableau takes a time dimension and a measure field to create a trend line.
5. Forecasting
Forecasting is about predicting the future value of a measure. Mathematical models capture the evolving trend or seasonality of the data and extrapolate them into the future. Once again, Tableau needs a time dimension and a measure field to create a forecast.
6. Business question
The question you will be answering is the following: Is the forecasted number of births in Japan during December 2019 higher than the average over the last five years?
7. Demo time!
Let's first see how to do a similar analysis for Portugal before answering the business question.