Compare a proportion with a benchmark

Test a stated event proportion using a count of events and trials.

Guides · Basic statistics · 4 min read

Example: first-scan label readability

300 different cartons under standard printer settings: 282 labels readable on the first scan.

Download the reference counts (CSV)

This is the same example used in Help. The CSV records reference counts for manual entry on Inputs; importing it does not configure the calculator. Use Open example in a practice copy in Help to prefill the counts.

1. Create the workspace

In the sidebar, open Basic Statistics and choose Proportions. Create an analysis, name it, select New blank worksheet, then choose Create analysis.

2. Enter the counts

On Inputs, choose One proportion for Test type. Enter 282 in Number of events (x) and 300 in Number of trials (n). Enter 0.95 in Hypothesized proportion (p₀). Here an event means readable on the first scan, not an unreadable label. Enter whole counts; no worksheet columns are assigned.

3. Set the test

Enter 0.05 in Significance level (α). The test is two-sided. This run tests the readability proportion against 95%.

Proportions: Inputs with the example’s assignments and settings
Inputs with the entered event counts, sample sizes and active test settings. View full-size image (opens in a new tab)

4. Run analysis

Choose Run analysis, then open Results.

5. Interpret results

  1. Define the counted event

    An event is a label readable on the first scan. Trials count different inspected cartons. This comparison uses only the standard-setting sample: 300 cartons.

  2. Read the proportions

    282 of 300 labels were readable: 94%. The sample is one percentage point below the 95% benchmark. That observed difference alone does not settle the population comparison.

  3. Read the test

    The two-sided p-value is 0.4268. This study does not establish a difference from 95% at the 5% level. It also does not certify that the 95% requirement has been met.

  4. Decide how to use the result

    Compare the estimated readability with the operational requirement and the cost of unreadable labels. Check sampling and scan conditions before attributing a change to printer settings.

More details: read each result section

Complete result tables use six significant digits, as in Help.

One-proportion z-test

z statistic standardizes the proportion comparison; p-value tests the stated null using the normal approximation. Alpha is 0.05 and Alternative two-sided. Sample proportions are fractions from the entered counts. Null proportion is the 0.95 benchmark; the z statistic is negative because the observed proportion is lower.

One-proportion z-test · 6 rows
StatisticValue
z statistic-0.794719
p-value0.426777
Alpha0.05
AlternativeTwo-sided
Null proportion (p₀)0.95
Sample 1 proportion0.94
  • No significant difference from 0.95 (p=0.427)

Summary counts

Successes count labels readable on the first scan; Trials count all inspected cartons in that sample. These are whole counts, not percentages. The samples use different cartons; no pairing or worksheet-column mapping is involved.

Summary counts · 1 row
SampleSuccessesTrials
Sample282300

6. Create a report

Keep the complete One-proportion z-test and Summary counts, event definition and sample identities. State that a non-significant difference does not certify a benchmark.

Choose Add to report from the completed run. Open Choose individual items and advanced options to select tables and charts, then choose Add to draft. Hidden items stay in the saved analysis.

Name the report and add the purpose of the study and your interpretation. Choose Save, review Preview, then use Export → Download HTML. The example below contains the full selected content, including results beyond one screen.

Complete native output for this Help example, including applicable tables, charts and run notes. Report numbers use the app’s displayed precision. Exported charts are static. On narrow screens, scroll wide charts and tables sideways.
View example report: Check standard label readability against 95%

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