Calculator Methodology:

The PSN Threat Probability and Severity Model provides a data-informed risk assessment tool that helps families evaluate whether to shelter in place or bug-out based on their location and level of preparedness. The model examines five key threat categories over a 10-year horizon: natural disasters, grid-down scenarios (EMP, cyber attacks, or solar flares), terror attacks, environmental hazards (such as pandemics, bioweapons, or chemical spills), and civil unrest.

These threats are scored across four location types—major U.S. cities, suburban areas, small-to-medium towns, and rural areas—using both estimated probability and severity of impact. Probability estimates were derived from public data including FEMA’s National Risk Index, DHS's 2024 Homeland Threat Assessment, and NOAA disaster frequency records, while severity scores account for factors like infrastructure dependence, population density, and supply chain fragility.

Each threat is assigned a risk score by multiplying its probability by severity, with results color-coded as green (acceptable, 0–0.49), orange (moderate, 0.5–1.0), or red (unacceptable, >1.0). Preparation levels—from 3-day to 90-day supplies—further reduce risk via modeled discount factors.

Final recommendations are issued based on risk outcomes: shelter in place if the situation score is green, conditional bug-out (to a secure location) if the situation score is orange, and bug-out if the situation score is red. Additional sources informing this model include the GAO’s grid infrastructure vulnerability reports, the CDC's pandemic preparedness strategy, and protest/unrest trends from ACLED. The result is a practical, defensible tool for modern preparedness decisions.

Limitations of the Model: Every situation is different, and no model can account for the unique factors and risks that may shape your particular emergency management situation. The above model is meant to assist in decision-making, but is not meant to replace your own judgement or the official guidance from government authorities. In any emergency situation, you should seek out, carefully consider, and follow the instructions from local, state, or Federal authorities, emergency responders, and emergency management professionals.
Chart: 10-Year Threat Probability and Severity by Location (with Citations