Totals, unique users and counting traps
Why the same week of data gives different numbers of 'active users', and how to count them right.
Lesson 2 of 32~22 min of learningIncludes ~13 min for questions and tasks
Contents1 of 39 steps
1 of 39 steps
Maya
The board deck is due Friday. I counted everyone in last week's export: 22 active users. Can that go on the slide?
🦉
You
The file has 147 rows, though. Which is the real number?
Alex Tutor
Neither, yet. 147 is the event total: every row, repeats included. 22 is the number of unique users: everyone with at least one row, counted once.
Alex Tutor
Dataset · 147 rows
Halves event log, 1–7 June (147 rows)
Every event from last week, in time order. Times are UTC.
- Columns
- event_time
- When it happened, in UTC
- user_id
- Who: the Halves account
- event
- What happened: app_opened, expense_added or settle_up_recorded
- platform
- Where the event was logged: ios, android or server
- entry_method
- expense_added only: manual, receipt_scan or recurring (created by the server)
- amount_usd
- Amount in US dollars, for expenses and settle-ups
- settlement_id
- settle_up_recorded only: which settlement the row belongs to
Data
| event_time | user_id | event | platform | entry_method | amount_usd | settlement_id |
|---|---|---|---|---|---|---|
| 2026-06-01T06:00:00Z | u001 | expense_added | server | recurring | 420 | |
| 2026-06-01T06:00:00Z | u005 | expense_added | server | recurring | 420 | |
| 2026-06-01T06:00:00Z | u015 | expense_added | server | recurring | 55 | |
| 2026-06-01T06:01:00Z | u001 | expense_added | server | recurring | 38 | |
| 2026-06-01T06:01:00Z | u015 | expense_added | server | recurring | 650 |
Show 142 more rows
| 2026-06-01T06:41:00Z | u008 | app_opened | ios | |||
| 2026-06-01T06:44:00Z | u007 | app_opened | ios | |||
| 2026-06-01T06:46:00Z | u007 | expense_added | ios | receipt_scan | 116 | |
| 2026-06-01T07:29:00Z | u019 | app_opened | ios | |||
| 2026-06-01T07:30:00Z | u019 | expense_added | ios | manual | 1 | |
| 2026-06-01T07:38:00Z | u002 | app_opened | android | |||
| 2026-06-01T07:39:00Z | u002 | expense_added | android | manual | 1 | |
| 2026-06-01T09:39:00Z | u002 | app_opened | android | |||
| 2026-06-01T09:40:00Z | u002 | expense_added | android | receipt_scan | 1 | |
| 2026-06-01T09:43:00Z | u019 | app_opened | ios | |||
| 2026-06-01T09:44:00Z | u019 | expense_added | ios | manual | 1 | |
| 2026-06-01T15:32:00Z | u008 | app_opened | ios | |||
| 2026-06-01T16:36:00Z | u020 | app_opened | android | |||
| 2026-06-01T16:38:00Z | u020 | expense_added | android | manual | 35 | |
| 2026-06-01T22:09:00Z | u009 | app_opened | ios | |||
| 2026-06-01T22:11:00Z | u009 | expense_added | ios | manual | 19 | |
| 2026-06-02T02:39:00Z | u018 | app_opened | ios | |||
| 2026-06-02T07:11:00Z | u002 | app_opened | android | |||
| 2026-06-02T07:12:00Z | u002 | expense_added | android | manual | 1 | |
| 2026-06-02T07:25:00Z | u019 | app_opened | ios | |||
| 2026-06-02T07:26:00Z | u019 | expense_added | ios | manual | 1 | |
| 2026-06-02T08:31:00Z | u016 | app_opened | ios | |||
| 2026-06-02T09:44:00Z | u019 | app_opened | ios | |||
| 2026-06-02T09:45:00Z | u019 | expense_added | ios | receipt_scan | 1 | |
| 2026-06-02T09:46:00Z | u002 | app_opened | android | |||
| 2026-06-02T09:47:00Z | u002 | expense_added | android | manual | 1 | |
| 2026-06-02T15:05:00Z | u018 | app_opened | ios | |||
| 2026-06-02T16:07:00Z | u014 | app_opened | ios | |||
| 2026-06-02T16:09:00Z | u014 | expense_added | ios | manual | 31 | |
| 2026-06-02T16:49:00Z | u004 | app_opened | ios | |||
| 2026-06-02T16:51:00Z | u004 | expense_added | ios | manual | 34 | |
| 2026-06-02T18:49:00Z | u014 | app_opened | ios | |||
| 2026-06-02T19:11:00Z | u004 | app_opened | ios | |||
| 2026-06-02T19:13:00Z | u004 | expense_added | ios | manual | 69 | |
| 2026-06-02T20:50:00Z | u020 | app_opened | android | |||
| 2026-06-02T23:10:00Z | u012 | app_opened | android | |||
| 2026-06-02T23:13:00Z | u012 | expense_added | android | manual | 19 | |
| 2026-06-02T23:14:00Z | u010 | app_opened | android | |||
| 2026-06-02T23:16:00Z | u010 | expense_added | android | receipt_scan | 8 | |
| 2026-06-03T02:30:00Z | u011 | app_opened | ios | |||
| 2026-06-03T02:33:00Z | u011 | expense_added | ios | manual | 89 | |
| 2026-06-03T07:14:00Z | u002 | app_opened | android | |||
| 2026-06-03T07:15:00Z | u002 | expense_added | android | manual | 1 | |
| 2026-06-03T07:53:00Z | u019 | app_opened | ios | |||
| 2026-06-03T07:54:00Z | u019 | expense_added | ios | manual | 1 | |
| 2026-06-03T09:19:00Z | u002 | app_opened | android | |||
| 2026-06-03T09:20:00Z | u002 | expense_added | android | manual | 1 | |
| 2026-06-03T09:37:00Z | u019 | app_opened | ios | |||
| 2026-06-03T09:38:00Z | u019 | expense_added | ios | manual | 1 | |
| 2026-06-03T10:02:00Z | u004 | app_opened | ios | |||
| 2026-06-03T10:04:00Z | u004 | expense_added | ios | manual | 105 | |
| 2026-06-03T10:07:00Z | u004 | settle_up_recorded | ios | 152 | s002 | |
| 2026-06-03T15:46:00Z | u018 | app_opened | ios | |||
| 2026-06-03T15:48:00Z | u018 | expense_added | ios | manual | 66 | |
| 2026-06-03T16:39:00Z | u021 | app_opened | ios | |||
| 2026-06-04T01:40:00Z | u017 | app_opened | ios | |||
| 2026-06-04T01:43:00Z | u017 | expense_added | ios | manual | 59 | |
| 2026-06-04T02:31:00Z | u008 | app_opened | ios | |||
| 2026-06-04T02:33:00Z | u008 | expense_added | ios | manual | 49 | |
| 2026-06-04T07:08:00Z | u019 | app_opened | ios | |||
| 2026-06-04T07:09:00Z | u019 | expense_added | ios | manual | 1 | |
| 2026-06-04T07:35:00Z | u002 | app_opened | android | |||
| 2026-06-04T07:36:00Z | u002 | expense_added | android | receipt_scan | 1 | |
| 2026-06-04T09:03:00Z | u002 | app_opened | android | |||
| 2026-06-04T09:04:00Z | u002 | expense_added | android | receipt_scan | 1 | |
| 2026-06-04T09:24:00Z | u019 | app_opened | ios | |||
| 2026-06-04T09:25:00Z | u019 | expense_added | ios | manual | 1 | |
| 2026-06-04T10:35:00Z | u020 | app_opened | android | |||
| 2026-06-04T12:22:00Z | u013 | app_opened | ios | |||
| 2026-06-04T12:27:00Z | u013 | settle_up_recorded | ios | 185 | s004 | |
| 2026-06-04T18:10:00Z | u020 | app_opened | android | |||
| 2026-06-04T18:12:00Z | u020 | expense_added | android | manual | 91 | |
| 2026-06-04T18:15:00Z | u020 | settle_up_recorded | android | 67 | s008 | |
| 2026-06-04T21:19:00Z | u013 | app_opened | ios | |||
| 2026-06-04T21:21:00Z | u014 | app_opened | ios | |||
| 2026-06-04T21:22:00Z | u014 | settle_up_recorded | ios | 185 | s004 | |
| 2026-06-04T23:48:00Z | u010 | app_opened | android | |||
| 2026-06-04T23:50:00Z | u010 | expense_added | android | manual | 95 | |
| 2026-06-05T02:13:00Z | u018 | app_opened | ios | |||
| 2026-06-05T02:15:00Z | u018 | expense_added | ios | manual | 36 | |
| 2026-06-05T06:24:00Z | u008 | app_opened | ios | |||
| 2026-06-05T06:26:00Z | u008 | expense_added | ios | manual | 101 | |
| 2026-06-05T07:17:00Z | u019 | app_opened | ios | |||
| 2026-06-05T07:18:00Z | u019 | expense_added | ios | manual | 1 | |
| 2026-06-05T07:21:00Z | u002 | app_opened | android | |||
| 2026-06-05T07:22:00Z | u002 | expense_added | android | receipt_scan | 1 | |
| 2026-06-05T09:11:00Z | u002 | app_opened | android | |||
| 2026-06-05T09:12:00Z | u002 | expense_added | android | manual | 1 | |
| 2026-06-05T09:40:00Z | u019 | app_opened | ios | |||
| 2026-06-05T09:41:00Z | u019 | expense_added | ios | receipt_scan | 1 | |
| 2026-06-05T12:36:00Z | u013 | app_opened | ios | |||
| 2026-06-05T12:37:00Z | u016 | app_opened | ios | |||
| 2026-06-05T12:39:00Z | u016 | expense_added | ios | manual | 40 | |
| 2026-06-05T12:44:00Z | u016 | app_opened | ios | |||
| 2026-06-05T14:27:00Z | u021 | app_opened | ios | |||
| 2026-06-05T14:29:00Z | u021 | expense_added | ios | manual | 11 | |
| 2026-06-05T15:23:00Z | u008 | app_opened | ios | |||
| 2026-06-05T15:25:00Z | u008 | expense_added | ios | receipt_scan | 84 | |
| 2026-06-05T18:05:00Z | u014 | app_opened | ios | |||
| 2026-06-05T18:30:00Z | u014 | app_opened | ios | |||
| 2026-06-05T18:32:00Z | u014 | expense_added | ios | manual | 64 | |
| 2026-06-05T21:03:00Z | u013 | app_opened | ios | |||
| 2026-06-05T21:05:00Z | u013 | expense_added | ios | manual | 17 | |
| 2026-06-06T00:05:00Z | u011 | app_opened | ios | |||
| 2026-06-06T00:08:00Z | u011 | expense_added | ios | manual | 73 | |
| 2026-06-06T05:40:00Z | u012 | app_opened | android | |||
| 2026-06-06T05:43:00Z | u012 | expense_added | android | manual | 21 | |
| 2026-06-06T08:32:00Z | u013 | app_opened | ios | |||
| 2026-06-06T14:21:00Z | u008 | app_opened | ios | |||
| 2026-06-06T14:23:00Z | u008 | expense_added | ios | receipt_scan | 16 | |
| 2026-06-06T16:08:00Z | u006 | app_opened | ios | |||
| 2026-06-06T16:10:00Z | u006 | expense_added | ios | receipt_scan | 41 | |
| 2026-06-06T18:05:00Z | u006 | app_opened | ios | |||
| 2026-06-06T18:07:00Z | u006 | expense_added | ios | receipt_scan | 22 | |
| 2026-06-06T18:10:00Z | u006 | settle_up_recorded | ios | 131 | s003 | |
| 2026-06-06T18:22:00Z | u013 | app_opened | ios | |||
| 2026-06-06T18:24:00Z | u013 | expense_added | ios | manual | 8 | |
| 2026-06-06T18:27:00Z | u013 | settle_up_recorded | ios | 138 | s005 | |
| 2026-06-06T19:01:00Z | u020 | app_opened | android | |||
| 2026-06-06T19:03:00Z | u020 | expense_added | android | manual | 6 | |
| 2026-06-07T02:38:00Z | u018 | app_opened | ios | |||
| 2026-06-07T02:40:00Z | u018 | expense_added | ios | manual | 32 | |
| 2026-06-07T02:43:00Z | u018 | settle_up_recorded | ios | 158 | s007 | |
| 2026-06-07T06:28:00Z | u003 | app_opened | ios | |||
| 2026-06-07T06:37:00Z | u007 | app_opened | ios | |||
| 2026-06-07T06:38:00Z | u007 | settle_up_recorded | ios | 158 | s007 | |
| 2026-06-07T10:04:00Z | u016 | app_opened | ios | |||
| 2026-06-07T10:05:00Z | u016 | settle_up_recorded | ios | 131 | s003 | |
| 2026-06-07T12:50:00Z | u021 | app_opened | ios | |||
| 2026-06-07T12:52:00Z | u021 | expense_added | ios | manual | 51 | |
| 2026-06-07T14:25:00Z | u018 | app_opened | ios | |||
| 2026-06-07T14:27:00Z | u018 | expense_added | ios | manual | 69 | |
| 2026-06-07T18:29:00Z | u003 | app_opened | ios | |||
| 2026-06-07T18:31:00Z | u003 | expense_added | ios | manual | 37 | |
| 2026-06-07T18:34:00Z | u003 | settle_up_recorded | ios | 69 | s001 | |
| 2026-06-07T19:14:00Z | u014 | app_opened | ios | |||
| 2026-06-07T19:16:00Z | u014 | app_opened | ios | |||
| 2026-06-07T19:18:00Z | u014 | expense_added | ios | manual | 15 | |
| 2026-06-07T19:21:00Z | u014 | settle_up_recorded | ios | 110 | s006 | |
| 2026-06-07T20:37:00Z | u022 | app_opened | ios | |||
| 2026-06-07T21:17:00Z | u022 | app_opened | ios | |||
| 2026-06-07T21:19:00Z | u022 | expense_added | ios | manual | 39 |
Alex Tutor
Dataset · 22 rows
Halves users in the log (22 rows)
One row per account that appears in the event log.
- Columns
- user_id
- The Halves account
- signup_date
- Date the account was created
- platform
- The user's phone platform: ios or android
- acquisition_channel
- How the user came to Halves: invite, app_store_search, paid_social, referral_link or staff
- timezone
- The user's home time zone
- is_internal
- true for a team account, false for a customer; not always filled in
Data
| user_id | signup_date | platform | acquisition_channel | timezone | is_internal |
|---|---|---|---|---|---|
| u001 | 2026-04-23 | ios | invite | Europe/Kyiv | false |
| u002 | 2026-02-10 | android | staff | Europe/Kyiv | |
| u003 | 2026-05-10 | ios | paid_social | Europe/Kyiv | false |
| u004 | 2026-05-22 | ios | paid_social | Europe/Kyiv | false |
| u005 | 2026-04-20 | android | app_store_search | Europe/Kyiv | false |
Show 17 more rows
| u006 | 2026-05-16 | ios | invite | Europe/Kyiv | false |
| u007 | 2026-05-08 | ios | referral_link | Asia/Bangkok | false |
| u008 | 2026-05-08 | ios | app_store_search | Asia/Bangkok | false |
| u009 | 2026-05-04 | ios | paid_social | Europe/Lisbon | false |
| u010 | 2026-05-29 | android | invite | America/New_York | false |
| u011 | 2026-05-28 | ios | invite | America/New_York | false |
| u012 | 2026-05-30 | android | invite | Asia/Bangkok | false |
| u013 | 2026-05-11 | ios | paid_social | Europe/Lisbon | false |
| u014 | 2026-05-30 | ios | referral_link | Europe/Kyiv | false |
| u015 | 2026-03-13 | android | invite | Europe/Kyiv | false |
| u016 | 2026-05-14 | ios | paid_social | Europe/Lisbon | false |
| u017 | 2026-06-01 | ios | paid_social | America/New_York | false |
| u018 | 2026-05-27 | ios | app_store_search | Asia/Bangkok | false |
| u019 | 2026-02-10 | ios | staff | Europe/Kyiv | true |
| u020 | 2026-05-06 | android | referral_link | Europe/Kyiv | false |
| u021 | 2026-05-12 | ios | app_store_search | Asia/Bangkok | false |
| u022 | 2026-05-11 | ios | app_store_search | Europe/Lisbon | false |
Alex Tutor:
u014 has 12 rows this week, u005 has one. In the total, u014 weighs twelve times more. In unique users, each counts once.
🦉
You
So “how many people” means unique users. Then 22 is right?
Alex Tutor
It counts people with any row. Before calling them active, look at who they are.
Alex Tutor
Question 1
u014 already opened Halves this week. Next week the same person opens it 10 more times than usual. True or false: both the event total and the number of unique users go up.
Alex Tutor
Some of the 22 have only one kind of row: an expense at 06:00 UTC on Monday,
platform = server, entry_method = recurring.Alex Tutor:
Those are server-side events: Halves added their monthly bills, like rent, automatically. These people never opened the app all week.
Maya
They pay for Plus, though. Don't they count?
Alex Tutor
As subscribers, yes. As active users, no. “Active” should mean the person did something. For Halves, let's say: opened the app at least once that week.
Alex Tutor
Question 2
Use the event log. How many unique users opened the app (app_opened) at least once during the week?
Units: users
🦉
You
Two accounts stand out: 20 rows each, and every expense is exactly $1.
Alex Tutor
A classic QA pattern: testers add tiny expenses to check that the app works. That's internal traffic, and it doesn't belong in product metrics.
Maya
Easy, there's an
is_internal flag. Filter it out.Alex Tutor
Try it: the flag catches one account. The other has an empty
is_internal, because someone forgot to set it. Another column in the users file gives it away.Alex Tutor:
Treat any flag set by hand as incomplete until you've checked it.
Alex Tutor
Question 3
Now remove every staff account, flagged or not. How many real users opened the app at least once during the week?
Units: users
Theo
For the store page I want “expenses added last week”. The file has 60
expense_added rows. Can I use 60?Alex Tutor
Same traps, now in an event count. Some of those rows were created by the server, and some were typed by the two QA accounts.
🦉
You
So I drop
recurring rows and both staff accounts, then count rows?Alex Tutor
Yes. Here counting rows is right, because each expense is exactly one event. What's wrong is the rows that no person added.
Alex Tutor
Question 4
Theo needs “expenses added by people last week”. Of the 60 expense_added rows, how many were added by real users in the app, without recurring bills and staff accounts?
Units: expenses
🦉
You
And settle-ups? There are 11
settle_up_recorded rows.Alex Tutor
Here rows overcount. The payer logs a settle-up, and the receiver's phone logs it again on confirmation. To count payments, count distinct
settlement_id.Maya
And “settle-ups per user”? Do I credit the payer or the receiver?
Alex Tutor
Depends on the question. Payments settled: count ids. People who settled up: count users on either side. Write down which one you mean.
Alex Tutor
Question 5
The log has 11 settle_up_recorded rows. How many settle-ups (payments) do they describe?
Units: settle-ups
Alex Tutor
Put it together. The same week gives four different “user” numbers, depending on what you filter out.
Alex Tutor
Maya
So the slide says 17? That looks worse than 22.
Alex Tutor
It's the number that survives when someone checks it. And put the definition under it, so everyone who recounts gets 17.
🦉
You
Weekly active users: real people, not staff, who opened the app at least once during the week.
Alex Tutor
Question 6Short answer · AI-checked task
Write to Maya in 2–3 sentences: why “22 active users” is wrong for last week and what number should go on the slide instead, with its definition.
Write your answer and get a score with feedback from our AI reviewer.
Log in to get AI feedbackAlex Tutor
Alex Tutor:
Your sentence is almost a metric definition. Next lesson we make it precise enough that nobody can read it two ways.
Alex Tutor
That’s the lesson. You answered every task — nicely done.