Help for Therblig, the stopwatch time study app for industrial engineers.
1. On the Studies screen, tap New study, then on the Setup tab break the job into 3–10 short elements with crisp, observable end points ("Pick to tote," not "do the work").
2. On the Observe tab, tap Start, then tap Lap the instant each element ends. The highlighted element is credited and the sequence advances automatically.
3. After several cycles, review readings on the Data tab and read your standard on the Results tab. A sample study ships with the app so you can explore safely first.
Each colored arc is one element, sized by its average observed time. One full revolution of the orange hand equals one mean cycle — if the hand laps faster than you do, the operator is behind the observed pace; slower, ahead. Before any data exists the dial simply sweeps once per 60 seconds.
Tap the specific element's pad instead of the big Lap button. The reading is credited to that element and the sequence continues from there.
Interruptions — a supervisor question, a dropped tote, a blocked aisle. Tapping it records the time so your clock stays honest, but keeps the reading out of every statistic.
Tap the undo button (↩) on the Observe tab. The last reading is removed and the sequence rewinds. The master clock is untouched.
On the Data tab, every reading is a dot on that element's strip. Tap a dot to exclude it (it turns hollow) or tap again to restore it. Excluded readings are left out of means, normal time, and sample-size checks — but they remain visible so your study stays auditable.
NT (normal time) = observed mean × performance rating × frequency. ST (standard time) = NT × (1 + PFD allowance). n′ is the number of cycles needed for ±5% precision at 95% confidence — if an element shows "need 14," keep timing until you have 14 readings for it.
On the Results tab, tap Westinghouse… on any element. Grade skill, effort, conditions, and consistency; the leveling factors sum and the resulting rating is applied to that element. You can always type a rating directly instead.
Tap the share icon at the top of any study. Therblig produces a CSV file — study header, full results table, and every raw reading — that opens directly in Excel, Numbers, or Google Sheets. Send it by Mail or AirDrop, or save it to Files.
All studies live on your device only — no account, no cloud service, nothing collected (see the Privacy Policy). Your studies are included in your normal iPhone backups, so restoring your phone restores your studies. Deleting the app deletes its data.
The free version includes two complete studies with every feature enabled. Therblig Pro is a single one-time purchase that removes the study limit forever. There is no subscription.
Open the unlock screen and tap Restore purchase. Make sure you are signed into the same Apple Account that made the purchase. Pro also supports Family Sharing.
Purchases are processed by Apple, so refunds go through them: visit reportaproblem.apple.com, sign in, and choose the purchase.