Step-by-Step GRR Study Execution Guide

Complete guide from planning to analysis and action

Study Overview

This comprehensive guide will walk you through executing a complete Gage R&R study, from initial planning to final recommendations.

Time Investment

Planning: 2-4 hours | Data Collection: 4-8 hours | Analysis: 2-3 hours | Total: 8-15 hours

Phase 1: Planning (Critical for Success)

Step 1: Define Study Objectives

Key Questions to Answer:

  • What measurement characteristic are we studying?
  • What is the intended use of this measurement system?
  • What level of precision is required?
  • What are the specification limits?
  • What decisions will be made based on this data?
Tip: Document these objectives clearly - they will guide all subsequent decisions.
Step 2: Select Operators

Requirements:

  • Number: 2-3 operators minimum
  • Training: All operators must be trained on the measurement procedure
  • Experience: Representative of typical users
  • Availability: Available for the entire study duration
Best Practice: Include both experienced and newer operators to capture realistic variation.
Step 3: Select Parts

Part Selection Criteria:

  • Number: 10 parts minimum (5 acceptable for preliminary studies)
  • Range: Span the expected measurement range
  • Variation: Include parts near specification limits
  • Condition: Representative of production parts
  • Stability: Parts should not change during the study
Our Tool Helps: Use our MSA-GRR Sample Selection Tool to optimize part selection!
Step 4: Prepare Equipment

Equipment Checklist:

  • Calibrate all measurement equipment
  • Verify environmental conditions
  • Prepare data collection sheets
  • Set up measurement station
  • Test measurement procedure

Phase 2: Data Collection (Execute with Precision)

Step 5: Execute Measurement Plan
Critical Success Factors
  • Randomization: Randomize the order of parts and operators
  • Blinding: Operators should not know previous measurements
  • Independence: Each measurement should be independent
  • Consistency: Use the same procedure for all measurements
Standard GRR Data Collection Pattern:
Part Operator A
Trial 1		 Operator A
Trial 2		 Operator B
Trial 1		 Operator B
Trial 2		 Operator C
Trial 1		 Operator C
Trial 2
Part 1X₁₁X₁₂X₁₁X₁₂X₁₁X₁₂
Part 2X₂₁X₂₂X₂₁X₂₂X₂₁X₂₂
.....................
Part 10X₁₀₁X₁₀₂X₁₀₁X₁₀₂X₁₀₁X₁₀₂
Quality Checks
During Data Collection:
  • Monitor for unusual readings
  • Verify part identification
  • Check environmental conditions
  • Document any anomalies
  • Maintain measurement sequence
Red Flags:
  • Measurements outside expected range
  • Systematic patterns in data
  • Equipment malfunctions
  • Operator confusion
  • Environmental changes

Phase 3: Data Analysis (Extract Insights)

Step 6: Calculate GRR Statistics
Key Calculations:
  1. Range Method:
    • Calculate ranges for each part/operator
    • Determine average range (R̄)
    • Calculate EV = R̄ × K₁
  2. ANOVA Method:
    • Perform two-way ANOVA
    • Extract variance components
    • Calculate %GRR, %EV, %AV
Software Options: Minitab, JMP, Excel templates, or statistical software
Step 7: Interpret Results
MetricExcellentMarginalUnacceptable
%GRR< 10%10-30%> 30%
NDC≥ 53-4< 3
P/T< 0.10.1-0.3> 0.3
Analysis Tips:
  • Look at %EV vs %AV to identify main sources
  • Check for operator-part interactions
  • Review control charts for patterns
  • Consider practical significance vs statistical

Phase 4: Take Action (Drive Improvement)

Step 8: Make Decisions
Acceptable System
%GRR < 10%

Actions:

  • Approve for production use
  • Document study results
  • Establish monitoring plan
  • Train operators
  • Schedule periodic re-validation
Marginal System
%GRR 10-30%

Actions:

  • Evaluate application criticality
  • Consider improvement opportunities
  • May be acceptable for some uses
  • Increase sampling if used
  • Monitor closely
Unacceptable System
%GRR > 30%

Actions:

  • Do not use for production
  • Identify improvement opportunities
  • Implement corrective actions
  • Re-run GRR study
  • Consider alternative methods
Step 9: Improvement Strategies
High Repeatability (%EV)

Equipment-related issues:

  • Calibrate or repair gage
  • Improve gage resolution
  • Control environmental conditions
  • Improve part fixturing
  • Reduce vibration/noise
  • Consider different measurement method
High Reproducibility (%AV)

Operator-related issues:

  • Improve operator training
  • Standardize measurement procedure
  • Improve work instructions
  • Add measurement aids/fixtures
  • Reduce operator subjectivity
  • Consider automation

Step 10: Document and Follow-up

Required Documentation
  • Study objectives and scope
  • Parts and operators used
  • Raw measurement data
  • Statistical analysis results
  • Conclusions and recommendations
  • Improvement actions taken
  • Approval for use (if applicable)
Follow-up Activities
  • Schedule periodic re-validation
  • Monitor measurement system performance
  • Track improvement action effectiveness
  • Update procedures if needed
  • Train additional operators
  • Share lessons learned

Tools and Resources

Use Our Tool

Optimize your part selection for GRR studies

Try Tool
Templates

Download data collection and analysis templates

Get Templates
Need Help?

Check our FAQ and troubleshooting guide

Get Help