Governing Equations

Response Surface Model (RSM):
  Y = β0 + βA·A + βB·B + βC·C + βAB·A·B + βAC·A·C + βBC·B·C + βAA·A² + βBB·B² + ε

Full Factorial (2³ = 8 runs + center points):
  A, B, C at low (-1) and high (+1) levels

Pareto Chart:
  Standardized effect = |effect| / SE
  Significant if > t-critical (≈ 2 for α=0.05)

R² and Q² (cross-validation):
  R² = 1 - SSres/SStot
  Q² = 1 - PRESS/SStot
  Q² > 0.5 → predictive model

Design Space:
  Region where all CQAs meet specification
  with acceptable probability

NOR (Normal Operating Range):
  Subset of design space for routine operation
  typically 95% confidence region