Cycle-count accuracy and sample size
Location accuracy from your last counts and how many locations to sample for a confident accuracy figure.
Get this tool with its role plan
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Comes with the data scientist plan: every tool for the role, from $10.20 a month at the launch price.
- Your own numbers, worked out as often as you like
- The full count sheet you can print or save to My work
- 4 cited sources, linked, with the checks to make
- Every other tool for the same role, in the same plan
- A plain-words read of your result (a fuller AI read with the Bifrost AI add-on)
Included in these role plans
Example result · fictional numbers
What you get: count sheet
Worked out by this tool from its default inputs. Its role plan lets you run your own numbers, print the sheet and save it.
Accuracy 97.75% (95% range 95.81% to 98.79%); count 11 locations a day, about 0.3 counter-hours
- Location accuracy
- 97.75%
- Sample size
- 208 locations
- Counts per day
- 11
- Share of locations sampled
- 1.7%
What the last count tells you
- Locations counted
- 400 locations of 12,000 locations
- Locations in error
- 9 locations
- Measured accuracy
- 97.75%
- 95% confidence range
- 95.81% to 98.79%
- Against your target
- Can't yet tell if you are above the 97.0% target: count more locations
Also on the sheet
- Count sheet for the next cycle · 6 lines, starting with “Sample size”
- ABC count plan for the year · 6 lines, starting with “A locations”
The plain-words read of this example
The last count found 9 locations in error out of 400 locations, so measured accuracy is 97.75%. At 95% confidence the true figure is between 95.81% and 98.79%. Can't yet tell if you are above the 97.0% target: count more locations. For ±2.0% next time, count 208 locations at random, 11 locations a day over 20 days. Your ABC plan adds 197 counts each count day, about 4.9 counter-hours.
4 cited sources
- NIST/SEMATECH e-Handbook of Statistical Methods, 7.2.4.1 Confidence intervals (proportions) (National Institute of Standards and Technology (NIST))
- NIST/SEMATECH e-Handbook, 3.3.3.3 Selecting sample sizes (National Institute of Standards and Technology (NIST))
- How to Use the Finite Population Correction (MeasuringU (Sauro and Lewis))
- NIST/SEMATECH e-Handbook, 7.2.4.2 Sample sizes required (National Institute of Standards and Technology (NIST))
Plus 5 step-by-step checks, a print layout and a link that reopens it with your numbers.