How many sessions do you need?

With three sessions, a 67% completion rate doesn’t mean much: one person more or less moves it by 33 points. That’s why DASHUND flags fragile results.

The “Small sample” label

Any metric calculated on fewer than 30 sessions carries the “Small sample” label. It’s still shown: the first sessions often already tell a lot, but read them as clues, not as proof.

What a few sessions can tell you

• A clear blocker: a screen where almost everyone stops, a button nobody finds.
• Clicks outside the planned areas, revealing an expectation the design doesn’t meet.
• Unexpected paths, to replay session by session.

When to aim for more sessions

• To compare two versions or two audiences: at least 30 sessions on each side.
• For a small difference (a few points of completion): many more, and over the same period.