Confronta i metodi

	Preliminary Hazard Analysis	Semi-Quantitative Risk Matrix Analysis
Campo	Disaster Studies	Disaster Studies
Famiglia	Process / pipeline	Process / pipeline
Anno di origine	2008	2019
Ideatore	Military system-safety practice (MIL-STD-882); codified in CCPS guidelines	ISO/IEC 31010 (standardized practice); critical analysis by L. A. Cox
Tipo	Early-stage qualitative hazard identification and ranking	Semi-quantitative consequence-likelihood rating and ranking pipeline
Fonte seminale	Center for Chemical Process Safety (CCPS). (2008). Guidelines for Hazard Evaluation Procedures (3rd ed.). Wiley-AIChE, Hoboken, NJ. ISBN: 9780471978152	International Organization for Standardization. (2019). IEC 31010:2019 Risk management — Risk assessment techniques. ISO/IEC, Geneva.
Alias	PHA, Preliminary Hazard List Analysis, Early Hazard Analysis, Conceptual Hazard Analysis	Risk Matrix Analysis, Consequence-Likelihood Matrix, Probability-Impact Matrix, Risk Rating Matrix
Correlati	3	3
Sintesi	Preliminary hazard analysis, or PHA, is an early-stage, qualitative technique for identifying the hazards inherent in a system before its design is detailed enough for more rigorous methods, and for ranking those hazards so that the riskiest receive attention first. Conducted in the concept or preliminary design phase, it works from the system's energy sources, hazardous materials, intended functions and operating environment to compile a hazard list, postulate how each hazard could lead to harm, and assign each a risk level from severity and likelihood ratings. The CCPS Guidelines for Hazard Evaluation Procedures present it as a foundational hazard-evaluation method, and ISO/IEC 31010 includes it among standard risk-assessment techniques. Because it is applied when changing the design is still cheap, the PHA's chief value is steering early design decisions and identifying which hazards warrant deeper study by methods such as HAZOP, FMEA or quantitative risk assessment.	Semi-quantitative risk matrix analysis rates each risk on ordinal likelihood and consequence scales and combines the two in a grid to assign a risk level that drives prioritization. It is the workhorse of practical risk management: ISO/IEC 31010 lists the consequence-likelihood matrix among its standard techniques precisely because it lets analysts compare many disparate risks quickly without the data demands of a full quantitative model. The 'semi-quantitative' label captures its hybrid character — ordinal categories such as 'rare' or 'catastrophic' are anchored to rough numeric bands, giving more discipline than a purely verbal judgment but far less than a probabilistic calculation. The method's popularity is matched by sharp critique: L. A. Cox's 2008 analysis in Risk Analysis showed that poorly designed matrices can rank risks incorrectly, compress very different risks into the same cell, and even perform worse than random, making careful scale design and consistency checks essential rather than optional.