Traffic
Monthly active users
Also called MAU.
Monthly active users is the number of distinct identifiers that sent a hit in a 28- or 30-day window. It is the broadest of the active-user counts.
How it is measured
Count distinct identifiers over the chosen window and report the window length with the figure. A rolling window changes every day; a calendar month is fixed. Both de-duplicate across days.
Tarsier keeps nothing across days, so a monthly figure is built from daily counts and cannot remove people who came on several days. Use it for direction. For an exact 30-day headcount you would need a login or a persistent cookie.
Worked example
A local news site reports 62,000 monthly active users in March and 71,000 in April. April has an election and a flood story. Weekly actives were 24,000 to 28,000 in most weeks but 39,000 in the flood week.
A publisher reading only the month would think growth was broad. The weekly pattern shows two news peaks.
How it differs
Monthly active users pools a month. Weekly active users pools seven days. Daily active users pools one. Dividing daily by monthly gives stickiness. MAU alone says nothing about frequency.
Common errors
Reporting MAU as paying customers. Comparing a 28-day window to a calendar month. Ignoring seasonality. Counting the same person on phone and laptop twice. Using MAU to size a market.
In practice
Pick a 28-day rolling window for trend and a calendar month for reports. Always pair it with the weekly figure, so a spike does not pass as growth.