Build a p chart

Example: carton labeling

A distribution center inspects 40 consecutive carton samples of different sizes. Each carton receives one final conforming or nonconforming decision.

Download the carton-labeling example (CSV)

This is the same example used in Help. Each row is one sample: sample_id names it, cartons_inspected is the sample size, and nonconforming_cartons counts cartons failing one or more checks. Count each carton only once.

1. Create the chart workspace

In the sidebar, open Process control, choose p Chart, and name the analysis. Select New blank worksheet and Create analysis.

2. Import the data

On Worksheet, choose Import. Select the downloaded file or paste its contents. Set the delimiter to Comma, use Decimal dot, and check First row contains column names. Preview the import, then choose Import into worksheet. Keep the rows in collection order.

3. Assign the input columns

On Inputs, assign sample_id to Subgroup label, nonconforming_cartons to Number of nonconforming units, and cartons_inspected to Subgroup size, selecting each from the column picker. Supply counts; the app calculates proportions from them.

Open Western Electric / AIAG rules. Leave all five optional rules On: 7-point trend, 6 on one side, 14 alternating, 2 of 3 beyond 2σ and 4 of 5 beyond 1σ.

p Chart: Inputs with the example’s assignments and settings — Sample labels, nonconforming-carton counts, inspected counts and enabled rules on Inputs. View full-size image (opens in a new tab)

4. Run analysis

Choose Run analysis, then open Results.

5. Interpret results

Understand each point
Each point is the proportion of cartons that fail inspection in one sample. For the first sample, 8 of 100 cartons fail: 8 / 100 = 0.08, or 8%. Count a carton once, even if it fails several checks. The chart center pools the counts: total nonconforming cartons divided by total cartons inspected, rather than an unweighted average of the sample percentages.
Compare each point with its limits
The overall nonconforming proportion is 6.014%. CTN33, CTN36, CTN37, CTN39 and CTN40 cross their upper limits. Sample sizes vary from 100 to 250 cartons, so the limits vary too. Smaller samples have wider limits.
Nonconforming proportions for 40 carton samples. Each sample has its own limits. View full-size chart (opens in a new tab)
Read the highlighted points
A highlighted point can cross a limit or belong to a pattern inside the limits. Several rules may flag the same sample. Use the signal details to see which rule applies; do not count the rows as separate process problems.
Decide what to investigate
Check the inspection and process records for CTN33, CTN36, CTN37, CTN39 and CTN40. Confirm that cartons were classified consistently. The chart locates unusual proportions; it does not explain why the cartons failed.

More details: read each result section

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

p chart summary

One carton is counted once as conforming or nonconforming. The center is total nonconforming cartons divided by total cartons inspected, not an unweighted average of the sample percentages.

p chart summary · 10 rows
Statistic / setting	Value
Subgroups (k)	40
Overall proportion (p̄)	0.0601418
Minimum sample size	100
Maximum sample size	250
Beyond-limit detection	On
7-point trend	On
6 on one side	On
14 alternating	On
2 of 3 beyond 2σ	On
4 of 5 beyond 1σ	On

Control limits and zones use each subgroup’s sample size or opportunities.

p values, control limits and zones

Each row lists inspected and nonconforming counts, their proportion and that sample’s limits. Use CTN labels to locate source rows. Compare proportions with their own limits because sample sizes vary.

p values, control limits and zones · 40 rows
Subgroup	Label	Nonconforming units	Sample size	p	CL	LCL	UCL	−1σ	+1σ	−2σ	+2σ	Signals
1	CTN01	8	100	0.08	0.0601418	0	0.131467	0.0363669	0.0839168	0.012592	0.107692	None
2	CTN02	13	250	0.052	0.0601418	0.0150321	0.105252	0.0451052	0.0751784	0.0300687	0.090215	None
3	CTN03	7	230	0.0304348	0.0601418	0.0131116	0.107172	0.0444651	0.0758186	0.0287884	0.0914953	None
4	CTN04	13	190	0.0684211	0.0601418	0.00839737	0.111886	0.0428937	0.07739	0.0256455	0.0946382	None
5	CTN05	3	110	0.0272727	0.0601418	0	0.128147	0.0374733	0.0828104	0.0148048	0.105479	None
6	CTN06	14	210	0.0666667	0.0601418	0.010923	0.109361	0.0437356	0.0765481	0.0273293	0.0929544	None
7	CTN07	14	230	0.0608696	0.0601418	0.0131116	0.107172	0.0444651	0.0758186	0.0287884	0.0914953	None
8	CTN08	10	180	0.0555556	0.0601418	0.00697945	0.113304	0.042421	0.0778626	0.0247002	0.0955834	None
9	CTN09	3	190	0.0157895	0.0601418	0.00839737	0.111886	0.0428937	0.07739	0.0256455	0.0946382	None
10	CTN10	3	110	0.0272727	0.0601418	0	0.128147	0.0374733	0.0828104	0.0148048	0.105479	None
11	CTN11	9	200	0.045	0.0601418	0.00970757	0.110576	0.0433304	0.0769533	0.026519	0.0937647	None
12	CTN12	18	250	0.072	0.0601418	0.0150321	0.105252	0.0451052	0.0751784	0.0300687	0.090215	None
13	CTN13	13	250	0.052	0.0601418	0.0150321	0.105252	0.0451052	0.0751784	0.0300687	0.090215	6 on one side
14	CTN14	9	180	0.05	0.0601418	0.00697945	0.113304	0.042421	0.0778626	0.0247002	0.0955834	6 on one side, 6 on one side
15	CTN15	5	250	0.02	0.0601418	0.0150321	0.105252	0.0451052	0.0751784	0.0300687	0.090215	6 on one side, 6 on one side, 6 on one side
16	CTN16	9	180	0.05	0.0601418	0.00697945	0.113304	0.042421	0.0778626	0.0247002	0.0955834	6 on one side, 6 on one side, 6 on one side, 6 on one side
17	CTN17	11	250	0.044	0.0601418	0.0150321	0.105252	0.0451052	0.0751784	0.0300687	0.090215	6 on one side, 6 on one side, 6 on one side, 6 on one side, 6 on one side
18	CTN18	8	180	0.0444444	0.0601418	0.00697945	0.113304	0.042421	0.0778626	0.0247002	0.0955834	6 on one side, 6 on one side, 6 on one side, 6 on one side, 6 on one side
19	CTN19	10	180	0.0555556	0.0601418	0.00697945	0.113304	0.042421	0.0778626	0.0247002	0.0955834	6 on one side, 6 on one side, 6 on one side, 6 on one side
20	CTN20	6	120	0.05	0.0601418	0	0.125252	0.0384384	0.0818453	0.0167349	0.103549	6 on one side, 6 on one side, 6 on one side
21	CTN21	9	240	0.0375	0.0601418	0.0141019	0.106182	0.0447952	0.0754885	0.0294485	0.0908352	6 on one side, 6 on one side
22	CTN22	6	180	0.0333333	0.0601418	0.00697945	0.113304	0.042421	0.0778626	0.0247002	0.0955834	6 on one side
23	CTN23	10	160	0.0625	0.0601418	0.00375461	0.116529	0.0413461	0.0789376	0.0225504	0.0977333	None
24	CTN24	4	120	0.0333333	0.0601418	0	0.125252	0.0384384	0.0818453	0.0167349	0.103549	6 on one side
25	CTN25	6	100	0.06	0.0601418	0	0.131467	0.0363669	0.0839168	0.012592	0.107692	6 on one side
26	CTN26	7	180	0.0388889	0.0601418	0.00697945	0.113304	0.042421	0.0778626	0.0247002	0.0955834	6 on one side
27	CTN27	5	120	0.0416667	0.0601418	0	0.125252	0.0384384	0.0818453	0.0167349	0.103549	6 on one side
28	CTN28	6	180	0.0333333	0.0601418	0.00697945	0.113304	0.042421	0.0778626	0.0247002	0.0955834	6 on one side
29	CTN29	5	130	0.0384615	0.0601418	0	0.122698	0.0392898	0.0809939	0.0184378	0.101846	6 on one side
30	CTN30	14	220	0.0636364	0.0601418	0.0120546	0.108229	0.0441128	0.0761709	0.0280837	0.0922	None
31	CTN31	4	140	0.0285714	0.0601418	0	0.120422	0.0400483	0.0802353	0.0199549	0.100329	None
32	CTN32	7	130	0.0538462	0.0601418	0	0.122698	0.0392898	0.0809939	0.0184378	0.101846	None
33	CTN33	20	150	0.133333	0.0601418	0.00190536	0.118378	0.0407297	0.079554	0.0213175	0.0989662	Beyond 3σ, 6 on one side, 2 of 3 beyond 2σ, 4 of 5 beyond 1σ
34	CTN34	7	100	0.07	0.0601418	0	0.131467	0.0363669	0.0839168	0.012592	0.107692	6 on one side, 6 on one side
35	CTN35	21	210	0.1	0.0601418	0.010923	0.109361	0.0437356	0.0765481	0.0273293	0.0929544	6 on one side, 6 on one side, 6 on one side, 2 of 3 beyond 2σ, 2 of 3 beyond 2σ, 2 of 3 beyond 2σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ
36	CTN36	19	160	0.11875	0.0601418	0.00375461	0.116529	0.0413461	0.0789376	0.0225504	0.0977333	Beyond 3σ, 6 on one side, 6 on one side, 6 on one side, 2 of 3 beyond 2σ, 2 of 3 beyond 2σ, 2 of 3 beyond 2σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ
37	CTN37	19	150	0.126667	0.0601418	0.00190536	0.118378	0.0407297	0.079554	0.0213175	0.0989662	Beyond 3σ, 6 on one side, 6 on one side, 6 on one side, 2 of 3 beyond 2σ, 2 of 3 beyond 2σ, 2 of 3 beyond 2σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ
38	CTN38	18	180	0.1	0.0601418	0.00697945	0.113304	0.042421	0.0778626	0.0247002	0.0955834	6 on one side, 6 on one side, 6 on one side, 2 of 3 beyond 2σ, 2 of 3 beyond 2σ, 2 of 3 beyond 2σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ
39	CTN39	27	170	0.158824	0.0601418	0.00543819	0.114845	0.0419073	0.0783764	0.0236727	0.0966109	Beyond 3σ, 6 on one side, 6 on one side, 2 of 3 beyond 2σ, 2 of 3 beyond 2σ, 4 of 5 beyond 1σ, 4 of 5 beyond 1σ
40	CTN40	24	190	0.126316	0.0601418	0.00839737	0.111886	0.0428937	0.07739	0.0256455	0.0946382	Beyond 3σ, 6 on one side, 2 of 3 beyond 2σ, 4 of 5 beyond 1σ

Control chart signal details

Each row names an inspection index or label and a rule. Beyond limits identifies a crossing; other rules flag patterns that may stay inside the limits. Several rules may flag the same sample. These entries identify inspections to investigate, not the number of defective cartons.

Control chart signal details · 93 rows
Index (as returned)	Chart	Rule
12	p	6 on one side
13	p	6 on one side
13	p	6 on one side
14	p	6 on one side
14	p	6 on one side
14	p	6 on one side
15	p	6 on one side
15	p	6 on one side
15	p	6 on one side
15	p	6 on one side
16	p	6 on one side
16	p	6 on one side
16	p	6 on one side
16	p	6 on one side
16	p	6 on one side
17	p	6 on one side
17	p	6 on one side
17	p	6 on one side
17	p	6 on one side
17	p	6 on one side
18	p	6 on one side
18	p	6 on one side
18	p	6 on one side
18	p	6 on one side
19	p	6 on one side
19	p	6 on one side
19	p	6 on one side
20	p	6 on one side
20	p	6 on one side
21	p	6 on one side
23	p	6 on one side
24	p	6 on one side
25	p	6 on one side
26	p	6 on one side
27	p	6 on one side
28	p	6 on one side
32	p	2 of 3 beyond 2σ
32	p	4 of 5 beyond 1σ
32	p	6 on one side
32	p	Beyond 3σ
33	p	6 on one side
33	p	6 on one side
34	p	2 of 3 beyond 2σ
34	p	2 of 3 beyond 2σ
34	p	2 of 3 beyond 2σ
34	p	4 of 5 beyond 1σ
34	p	4 of 5 beyond 1σ
34	p	4 of 5 beyond 1σ
34	p	6 on one side
34	p	6 on one side
34	p	6 on one side
35	p	2 of 3 beyond 2σ
35	p	2 of 3 beyond 2σ
35	p	2 of 3 beyond 2σ
35	p	4 of 5 beyond 1σ
35	p	4 of 5 beyond 1σ
35	p	4 of 5 beyond 1σ
35	p	4 of 5 beyond 1σ
35	p	6 on one side
35	p	6 on one side
35	p	6 on one side
35	p	Beyond 3σ
36	p	2 of 3 beyond 2σ
36	p	2 of 3 beyond 2σ
36	p	2 of 3 beyond 2σ
36	p	4 of 5 beyond 1σ
36	p	4 of 5 beyond 1σ
36	p	4 of 5 beyond 1σ
36	p	4 of 5 beyond 1σ
36	p	6 on one side
36	p	6 on one side
36	p	6 on one side
36	p	Beyond 3σ
37	p	2 of 3 beyond 2σ
37	p	2 of 3 beyond 2σ
37	p	2 of 3 beyond 2σ
37	p	4 of 5 beyond 1σ
37	p	4 of 5 beyond 1σ
37	p	4 of 5 beyond 1σ
37	p	6 on one side
37	p	6 on one side
37	p	6 on one side
38	p	2 of 3 beyond 2σ
38	p	2 of 3 beyond 2σ
38	p	4 of 5 beyond 1σ
38	p	4 of 5 beyond 1σ
38	p	6 on one side
38	p	6 on one side
38	p	Beyond 3σ
39	p	2 of 3 beyond 2σ
39	p	4 of 5 beyond 1σ
39	p	6 on one side
39	p	Beyond 3σ

Endpoint signal indices start at 0; chart subgroup numbers start at 1.

6. Create a report

Keep the p control chart, summary, sample values and limits, and signal details. Record the inspection basis and what you checked in CTN33, CTN36, CTN37, CTN39 and CTN40. Retain each sample’s size alongside its proportion.

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.

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