I'd recommend checking out this blog post from Jonathan Drummey:
There's a sample workbook published to Tableau Public at the bottom of the post. Hope this helps!
Hi Dan - I've reviewed this tutorial before and it was helpful for me to compute a different monthly view for comparing monthly forecast/monthly revenue actuals in the bars & variance % to forecast in the lines. Where it was lacking was time-series data with different years to compare.
But I was able to find a solution after reviewing the article you posted again.
1. Like in the tutorial, transform the current date values to +/- set amount of days so the bars can be grouped on an exact date axis. Called this calc'd field: Period Transformation
WHEN 2014 THEN DATETRUNC('month',[Period]) - 8
WHEN 2015 THEN DATETRUNC('month',[Period]) + 8
2. The using the DATEADD function pushed all date values into 2015. If year < 2015, add 12 months, if 2015 keep the current date.
IF YEAR([Period Transformation]) < 2015 THEN DATEADD('month',12,[Period Transformation]) ELSE [Period Transformation] END
3. Dropped this on an exact date axis and now we're set!