1. Conduct a Key Assumptions Check of the initial theory that the young Navajo couple died from a particularly virulent common flu virus. Indicate whether each is supported, in need of caveats, or unsupported. Explain your reasoning. Key Assumption Evaluation Reasons 1. Cause of death is highly potent flu virus With Caveats Symptoms are similar to those of flu but flu strain would have to be unique to area. 2. Navajos are being targeted. Unsupported There is no evidence that someone is intentionally targeting Navajos. 3. 4. 5. 6. 2. Were one in four key assumptions unsupported, as is usually the case? 3. How would a Key Assumptions Check have helped CDC investigators working on this issue?