Calculated Fields, Table Calculations, and Statistics
It won’t be too long before you encounter a situation where the data in your underlying data source or database won’t fit your analysis needs exactly. For example, you may need to calculate the result of one or more numeric measures in your data source to determine a desired number you wish to analyze. Or, a dimension in the data source may not be organized precisely in the way you wish to use it.
For these types of situations, Tableau provides calculated fields. A calculated field is a custom calculation (often simply referred to as a formula) that can use combinations of existing ...

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