The Two Proportions Test is a hypothesis tests that can be used to determine whether the proportion defective of one strata of a process is statistically different from the proportion defective (or yield) of another strata of a process. It is useful for determining whether a particular strata or group could provide insight into the root cause of process issues.

An example would be testing if the product defect rates are truly different for two separate production lines or whether the difference is due to random chance.

For a better understanding of the Two Proportions Test, check out our Black Belt Training & Certification Course!

Elisabeth Swan

Elisabeth is a Managing Partner & Executive Advisor at GoLeanSixSigma.com. For over 25 years, she's helped leading organizations like Amazon, Charles Schwab and Starwood Hotels & Resorts build problem-solving muscles with Lean Six Sigma to achieve their goals.

Tracy O'Rourke

Tracy is a Managing Partner & Executive Advisor at GoLeanSixSigma.com. She is also a Lean Six Sigma Green Belt Instructor at University of California San Diego and teaches in San Diego State University’s Lean Enterprise Program. For almost 20 years, she has helped leading organizations like Washington State, Charles Schwab and GE build problem-solving muscles.