Importance of Reference Lines and Bands

Reference Lines

A reference line is a visual indicator used to highlight a certain threshold or key values like average, median, percentile etc. They help in creating more meaningful visualizations and are an integral part of Quality control charts where you have an upper and lower control limit. By adding reference lines, we can compare data points with either static value or aggregate values like average of the measure.

Consider an example, wherein a Manger would like to review his Sales Reps performance. With the help of the reference line, the Manager can easily understand that Mary and Patricia are the only 2 who haven’t met their Sales Target for the current quarter.

The above chart has been created in SAP Lumira Designer using VBX. Using VBX one is not only limited to Bar and Column chart to create reference lines. Following visualization also support reference lines

Box plot
Fixed Column Chart
Line chart
Stacked charts (Bar / Column / Area)
Dual Axis / Multi Axis Chart
Scatterplot / Bubble chart
Bullet chart
Advanced Gauge

Reference Bands

Reference bands or Plot bands as they are popularly called are shaded plot area between two reference lines used to highlight values which lie under a certain range. One can have reference bands both on X and Y axis depending on the use case.

Y Axis

For example, you may want to highlight values beyond the current month as forecasted values.

X Axis

Consider an example, where you want to highlight the Warehouse, whose stock for a particular product is below the set threshold value.

Variable limits

Instead of having static limits, plot bands can also have variable limits. They are mainly used in cases where the upper and lower limit vary according to the data point. Example – Confidence bands, Bollinger Bands, variable QC limits etc.

The following use case have been developed using VBX – Dual Axis Chart

Stock price – high, low and closing price

In the following chart, one can easily visualize the highs and lows of the day along with the closing price of the stock.