Your test isn't perfect. Here's what might skew the results:

• Roast date: A fresh arabica will beat a stale robusta, no contest. Check the roast date on the bag.
• Grind size: If you're pre-ground, consistency matters. A bad grind ruins any bean.
• Water quality: Travel water can be funky. That affects taste more than the bean type.
• Your mood: Caffeine can bias you. If you're exhausted, robusta's kick might make it taste better than it is.

Don't let these derail you. Just note them and move on.