Heatmaps, another way to spot seasonality
This post owes a lot to a recent (at time of publication) talk by Andy Congreve at the London Tableau User Group. Time has become a subject where more often than not we default to a particular chart type when it is not always the most appropriate for example, if i was told to trends in sales over time I might produce a graph that looks a little like this:
This is fine, it show the general trend of sales over time as an increasing trend but its not very good at showing the seasonality of sales. One way to show this seasonality would be with a heat map, to do this simply place the date field you wish to use on either the rows or columns. Duplicate this field and place the copy on the other shelf.
I prefer to use Month on columns and day on rows but you might prefer to set it up the other way round or to use different date parts entirely.
Once the date has been set up we can place our values onto the view, simply drag and drop the measure you want to explore onto the colours shelf.
There you have it, one heatmap, and now you can see clearly the seasonality(if it exists) in the data, I find that I often use heat maps to conduct an initial exploration of my data to try and pick out some sort of trend or pattern.
Heat maps are also the basis of that most oft requested feature, tables with conditional formatting, simply duplicate your measure and place it on the label shelf and then change the mark type to square, this will give you a table with cells formatted conditionally.
Hope you have found todays top tip useful and once again big shout out to Andy Congreve for the basis of this tip.