3.4 Data validation and protecting a model
Other people can use your workbook without breaking it.
Before:02. Excel — Formulas & FunctionsUnlocks:05. Excel — Charts & Dashboards
Data validation puts guardrails on cells — dropdown lists, date limits, custom rules — and sheet protection locks the formulas, so a workbook can survive being used by other people. It sits among the analysis topics because a model is only as good as the inputs people are able to type into it. The common confusion is that validation checks values only as they are typed: it does not clean what was already there, and a paste can sail straight past it, which is why protection is taught alongside.
Work through these
Dropdown lists from a range or a table
A dropdown built from a list means people choose rather than type, which removes an entire category of inconsistent data. It is the single highest-value control in this topic.
Number, date and custom validation rules
Rules can require a number in a range, a date within limits, or anything a formula can express. The last kind is what lets you encode a real rule rather than an approximation.
Input and error messages that explain what to do
A message shown before entry and a message shown after a rejection are what make a rule feel helpful rather than obstructive. Without them, users work around the control.
Protecting sheets and locking formula cells
Locking the formula cells and protecting the sheet lets other people enter data without disturbing the machinery. It is what turns a workbook into something you can hand over.
Practice file
- xl-07-dashboard-starter.xlsx
Clean data plus an empty dashboard sheet with the five questions written on it.
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