Excel Data Validation: Ensuring Accurate and Consistent Data Entry

With the number of people who pass spreadsheets off to one another, mistakes are bound to happen. That's where Data Validation comes in to save the day (hopefully).

Data validation in Excel is a feature that allows you to define rules that restrict the type of data or the values that can be entered into a cell. This helps to prevent errors and ensures that the data entered meets specific criteria. Basically, it's a protective measure against fat-fingering.

Why Use Data Validation?

Accuracy: Prevents incorrect data entry.

Consistency: Ensures data entered follows a consistent format or set of rules.

Efficiency: Reduces the need for data cleaning and corrections later.

Guidance: Provides users with clear instructions on what data is acceptable.

How to Set Up Data Validation

Setting up data validation in Excel is straightforward. Here's a step-by-step guide:

1. Select the Cell(s) or Range

Click on the cell or select the range of cells where you want to apply data validation.

2. Open Data Validation Dialog Box (Alt,A,V,V)

Go to the Data tab on the Ribbon.

Click on Data Validation in the Data Tools group.

In the drop-down menu, select Data Validation.

3. Define Validation Criteria

In the Data Validation dialog box, go to the Settings tab.

Choose the type of validation criteria you want to apply from the Allow drop-down list (e.g., Whole Number, Decimal, List, Date, Time, Text Length, Custom).

Specify the conditions based on your selected criteria.

I'm going with a List in this example.

Optional: Error Alert

You have three options for how your data validation works. Stop is the default. You can also customize an error message to the users.

Stop – hard no; prevents invalid data from being entered

Warning – soft no; warns users that the data entered is not valid

Information – softer no; informs users that the data entered is not valid… semantics

4. Click OK to apply the data validation rules to the selected cell(s).

The cell dropdowns are then available when you choose list.

Data Validation Use Cases

Restricting to Whole Numbers. Useful for things like inventory control when fractional units are not allowed.

Restricting Numeric Range. Maybe your employees are hand keying transactions and you know you'll never have a transaction exceeding $10,000. You can cap it so they can't accidentally put $100,000.

Drop-down Lists are useful for anything where restricting the options is helpful for data standardization. Maybe you have some people inputting "HR" and others as "Human Resources" and that causes data aggregation problems. Forcing a selection from a list is very useful. Bonus: you can also use a range for lists, which can then make it easier to add new values.

Restricting Dates. If you've ever had a transaction from the early 1900s in any of your spreadsheets, you understand the need for this.

Ensuring product codes are exactly 10 characters long.

Tips for Effective Data Validation

Be Clear with Messages. Use clear and concise input and error messages to guide users.

Combine Criteria. Use multiple validation criteria to create comprehensive rules.

Test Your Validation. Test your data validation rules to ensure they work as expected.

Document Your Rules. Document the validation rules for future reference and maintenance.

As always with FML tips, this is primarily for exposure to what's possible. There are advanced ways to use Data Validation with formulas and ranges, but we're going with the basics for now.