Statistical Process Control Analysis Made Simple

The choice depends on your data type and measurement method. For continuous measurements like dimensions or temperatures, use X-bar and R charts. For attribute data like pass/fail or defect counts, use p-charts or c-charts. Sourcetable's AI assistant analyzes your data and recommends the most appropriate chart type automatically.

For X-bar and R charts, subgroup sizes of 4-5 are typical, providing good sensitivity to process changes. For attribute charts, larger sample sizes (usually 50-100) provide more reliable statistics. The key is consistency—use the same subgroup size throughout your analysis.

Control limits should be recalculated when you make intentional process changes, such as equipment upgrades or procedure modifications. Avoid recalculating limits simply because you have out-of-control points—this defeats the purpose of SPC. Generally, review limits quarterly or after significant process improvements.

Absolutely! SPC works for any measurable process. Service industries use SPC to monitor call center performance, patient wait times, loan processing times, and customer satisfaction scores. The key is identifying measurable outputs that matter to your customers.

Common cause variation is the natural, predictable variation inherent in any process. Special cause variation indicates something unusual has occurred—equipment malfunction, material change, or operator error. SPC helps you distinguish between the two, so you don't waste time investigating normal variation.

Many SPC techniques assume normal distribution, but real processes often aren't perfectly normal. For highly skewed data, consider data transformations or use alternative techniques like individual charts. Sourcetable can detect data distribution patterns and suggest appropriate analysis methods.

Yes! Sourcetable can connect to live data sources and update control charts automatically. Set up alerts for out-of-control conditions, and your team will be notified immediately when processes require attention. This is especially valuable for continuous processes that run 24/7.

Focus on business impact rather than statistical details. Show how SPC prevents customer complaints, reduces scrap costs, or improves efficiency. Use capability indices to demonstrate process performance relative to specifications. Sourcetable generates executive-ready reports that highlight key findings and recommendations.