I noticed there are two different types of calculations in Watson Analytics, Member Calculations and Simple Calculations. What is the difference between the two?
There are two types of calculations that can be created within Watson Analytics – simple calculations and member calculations. Calculations are important for solving problems and help immensely in making the right decisions based on the data available.
This type of calculation is referred to simply as ‘Calculation’ within the Watson Analytics user interface. This can be created in Refine, Discover and Display.
When created in Refine, the calculated field is added as a column in your dataset which can be added to any visualization. They help you define relationships between items of interest. For example, creating calculations such as ‘variance’ in a cost-benefit analysis will help you compare costs to revenues and actual sales to projected sales across products.
When a calculation is created in Discover or Display, it is added as a column in the data tray and can only be used in the visualizations with the same Discovery set or Display. This calculated column is not stored with the data, as seen in Refine. If you would like calculations based on aggregated data, creating them in Discover enables you to do that. For example, if you are looking to create weighted average across the sum of all values within the column, then you would create a calculation in Discover.
Member calculations can only be created in Discover or Display. This should be used when the new calculated item needs to depend upon the values of other items in a column. For example, a member calculation can be used to get the difference between two successive years and then show this over ‘product group’. These item based calculations are only available in the discovery set where you created them and will not be stored with the data as seen in Refine.
We encourage you to stay tuned to our blog for upcoming posts which will specifically discuss various functions which can be used to create Simple and Member calculations in Watson Analytics.
Please review the available documentation regarding Calculations for a more in depth discussion of the functions available, and how to effectively use them.