The core concepts of specificity, accuracy, precision, range and robustness.
Intended purpose comes first
Validation is not a universal quality stamp. It demonstrates that a procedure performs suitably for a defined use, matrix, range and result type. An analytical target profile helps define requirements before experiments are selected.
Performance characteristics
Specificity addresses interference, accuracy closeness to an accepted value, and precision the spread of repeated measurements. Linearity and range connect response to amount, while detection or quantitation limits are needed when relevant to the purpose.
Development, validation and lifecycle
Robustness is commonly studied during development to understand deliberate small variations. Validation confirms performance under defined conditions, and ongoing monitoring detects change. The full system is stronger than a one-time test.