What distinguishes frequency analysis from consequence analysis?

Frequency analysis and consequence analysis are distinguished by what they measure and how they contribute to risk assessment: frequency analysis estimates how often a hazard is likely to occur, while consequence analysis evaluates the potential severity or impact if that hazard does occur. Frequency analysis, also known as probability assessment, focuses on determining the likelihood of a specific event or hazard occurring within a given timeframe. This can be based on historical data, statistical analysis, expert judgment, or a combination of these methods. The result of frequency analysis is typically expressed as a numerical value, such as the number of occurrences per year, the probability of occurrence within a specific timeframe, or a qualitative ranking (e.g., rare, occasional, frequent). Consequence analysis, also known as severity assessment, focuses on evaluating the potential impact or severity of a hazard if it were to occur. This includes considering the potential for injury, illness, property damage, environmental damage, and other negative outcomes. The result of consequence analysis is typically expressed as a qualitative ranking (e.g., minor, moderate, severe, catastrophic) or a numerical value representing the potential cost or damage. While frequency analysis tells you how likely something is to happen, consequence analysis tells you how bad it would be if it did happen. For example, in a risk assessment of a railway grade crossing, frequency analysis might estimate the likelihood of a vehicle crossing the tracks while a train is approaching. Consequence analysis would evaluate the potential severity of a collision between a train and a vehicle, considering factors such as the speed of the train, the size of the vehicle, and the number of people involved.