A single trend is a trend chart that shows a single unit and a single item. The chart is typically used in visualizing MI to compare actual and forecast performance against budget, target or prior year.
Here are some examples, starting with a simple single trend bar chart.
- Time is the horizontal axis, as it always should be
- The bars start at a baseline of 0, as they always should in this type of chart
- Axes are labelled, where appropriate with the unit of measure
- All relevant dimensions of data in the chart are labelled, so the reader knows what is being shown
- Note the faint gridlines and clear, consistent font (PT Sans)
- The background is clean and light
- The legend has no border and is less prominent than the data objects it labels
- The bars have no border or fill pattern
- The bars do not overlap
- White space between bars = bar width +/- 50%
- The dashed vertical line indicates the current period up to which we have reported actuals
We now add a new data series to the chart: monthly budget values.
- The budget bars act as the key comparator for the actuals
- The lack of white space between the budget bars removes the ‘fringing’ effect we would otherwise experience, which is distracting to the brain
- The important ability to easily compare an actual value against its corresponding budget is preserved
The year to date variance of actual vs budget is now added.
- The variance for the year to date is shown as a negative value because actual sales have been lower than budget for each month so far (see the discussion in this post concerning the variance indicator)
- The cumulative variance of actual vs budget for the year to date is $61.5 million adverse
We now add the current management forecast for the remainder of the year, phased by month.
- The colours of each element work well together and are easy on the eye
We can now extend the year to date variance of actual vs budget to include the variance of forecast vs budget for the rest of the year.
- The cumulative variance at the end of the financial year indicates that the current management forecast for sales is lower than the budget by $58 million
We can now overlay the corresponding sales values for last year as marker bars.
- The heavier part of the marker bar line is the data measure, connected by thin vertical lines
Alternatively, we can calculate a Moving Annual Average (MAA) and overlay this on the chart to show the underlying trend.
We can now extend the time trend back by two further years.
- Note that the MAA line starts at the beginning of the second year, since we have collected no further year of historical actuals
In this version of the chart, we have replaced the MAA line by a best fit line through the actuals, which also highlights the underlying trend.
To summarise, the single trend bar chart is a very versatile chart that enables the trend of actuals and forecasts to be evaluated over any reasonable time span.