Often data is not entirely clean. That is, it has problems that need to be corrected before much meaningful analysis can be accomplished. For example, dates may be incorrectly formatted or fields may contain a mix of numeric values and character codes that need to be separated into multiple fields. Calculated fields can often be used to fix these kinds of issues.

We will make use of the sample data introduced at the beginning of this chapter, which contained date values like this:

The original source was Excel and the start date was stored as a text value and the end...