Spc

Analyze process variation with control charts and capability indices.

Updated Aug 23, 2026
One-click install
npx skills add https://github.com/robdtaylor/personal-ai-infrastructure --skill spc
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: Spc
Source: https://github.com/robdtaylor/personal-ai-infrastructure/tree/main/skills/Spc
Command: npx skills add https://github.com/robdtaylor/personal-ai-infrastructure --skill spc

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

SPC provides a structured approach to monitoring, understanding, and improving processes by distinguishing common from special causes of variation and by quantifying capability.

Core Features & Use Cases

  • Chart selection guidance: Choose appropriate X-bar/R or I-MR charts for given data structure.
  • Capability analysis: Compute Cp, Cpk, Pp, Ppk and interpret results against automotive and general standards.
  • Out-of-control rules: Apply Western Electric and Nelson rules to detect signals and drive action.
  • Templates & references: Includes practical templates for capability studies and reference guides for chart selection, indices, and rules.
  • Use cases: For a machining line with multiple cavities, you can set up X-bar/R charts and assess the capability to meet tolerances, triggering reaction plans when signals appear.

Quick Start

Use the SPC skill to assess a newly collected data batch by selecting X-bar/R charts, calculating R̄, X̄, and control limits, and interpreting Cpk and Ppk values with the provided templates.

Frequently Asked Questions about Spc

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I calculate process capability indices like Cpk and Ppk for manufacturing data?

Process capability indices like Cpk and Ppk are calculated by comparing process variation to tolerance limits. This skill computes Cp, Cpk, Pp, and Ppk values using standard templates and interprets results against automotive and general standards.

How do I set up X-bar/R control charts for multi-stream machining line data?

X-bar/R control charts for multi-stream data are set up by calculating R̄ and X̄ to establish control limits. This skill provides chart selection guidance to choose appropriate X-bar/R or I-MR charts based on your specific data structure.

What Western Electric and Nelson rules detect out-of-control signals in SPC charts?

Western Electric and Nelson rules detect out-of-control signals by identifying non-random patterns in control chart data. This skill applies these specific statistical rules to trigger reaction plans and drive improvement actions when signals appear.

When do I need to use I-MR charts instead of X-bar/R charts for statistical process control?

I-MR charts are needed for individual measurements rather than subgroups, typically for long-cycle measurements or batches. This skill provides reference guides to help select between I-MR and X-bar/R charts based on your data structure.

Can I perform SPC analysis on service processes or is it limited to manufacturing?

SPC analysis applies to both service processes and manufacturing, including setups, batches, and long-cycle measurements. This skill distinguishes common from special causes of variation and quantifies capability across diverse process types.

How do I assess if a newly collected data batch meets tolerance specifications?

To assess if a newly collected data batch meets tolerances, select appropriate control charts and calculate capability indices. This skill evaluates process variation against specifications to determine if the process is capable.