Each stop below runs LimitLine's real calculation engine on an example dataset, draws the chart, and lists every number with the formula behind it. The first examples come from the NIST/SEMATECH e-Handbook, so you can check them against a public source.
One measurement at a time, in time order. LimitLine finds the process's normal wobble and draws the limits it should stay inside. Example: 10 measurements from the NIST handbook.
The gap between each measurement and the one before it. This is where the short-term spread (σ) comes from, so a jump here means the process got noisier.
Limits are frozen from the first 10 points (a baseline), then 5 new measurements arrive. LimitLine checks the 8 Nelson rules and marks any point that breaks one with an orange triangle.
Control limits describe what the process does. Spec limits describe what the customer needs. Capability compares the two. Example specs: LSL 45 and USL 57 on the same 10 measurements.
Several measurements per sample, for example 5 parts every hour. The X̄ chart tracks each sample's average; the R chart tracks each sample's range. Example: 8 samples of 5, specs 9.4 to 10.6.
Pass/fail counting. Each point is the share of bad items in a sample. Example: NIST's 30 wafers with 50 chips each.
Counting defects, where one unit can have several. Example: NIST's 25 wafers.
Answer two or three questions and LimitLine opens the right chart. These are its real answers.
Settings in the “Customize charts” panel. The signals chart above already uses several of them: a baseline, a note on point 13 and color-blind-safe colors.
“Line 3 — shaft diameter”, “Diameter (mm)”, 0–5 decimals. Free.
Draw the nominal value; judge Cpk against 1.33, 1.67 or your customer's number. Free.
Color-blind safe (default), classic, high contrast, print. Signals are triangles in every style. Free.
Limits from the first N points; leave out known special causes such as “13, 20-22”. Pro.
“13: new material lot” on the chart; dates or lot numbers along the bottom. Pro.
Copy an image (Free). Download PNG, SVG, or the data with limits as CSV (Pro).
Photograph a check sheet, open a PDF, Word or Excel file, or screenshot a chart, and LimitLine fills in the numbers for you to check. Free includes 1 scan a day, Pro and Student 20, and Team and Expert are unlimited. Below, the real engine reads a chart drawn on this page as a picture (pixels only, no hidden data) and cleans up a misread sheet.
Expert writes the summary for you from the numbers. No person reads your data; the report below is generated by rules from the capability example.
All figures on this page are computed live by LimitLine's engine (the same code as the app, 133 automated checks). Sources: NIST/SEMATECH e-Handbook of Statistical Methods — individuals chart example, capability, p chart data, c chart. The subgroup example is illustrative data.