Actual data helps improve interface design

We’re guilty of using guesses/gut feelings when putting a site together. Nielsen reminds us that even a few data points can help make better design decisions.

Guesses vs. Data as Basis for Design Recommendations (Jakob Nielsen’s Alertbox)

The general guideline is to use relative font sizes that let users resize (if they know how), but to display big and legible text as the default. This conclusion is based on numerous observations that show that many older users don’t have the skills to resize fonts.