You are going down a jungle trail when you hear a stir in the undergrowth. A twinge of fear grips you. Another rustling sound sends you running down the path as fast as you can. Why did you do it? You thought some animal, possibly a predator, was about to spring out at you. However, the rustling was generated by a gust of wind. You created a "false positive" mistake. Later, you follow the same path and notice a rustle in the undergrowth. "Just a gust of wind," you tell yourself as you proceed down the trail, only to be smacked by a leopard. You made a "false negative" error, which has catastrophic implications. We learn to notice patterns at a young age, and these patterns may or may not be relevant. It may be prudent to treat all strange events as potentially life-threatening until our experience with them demonstrates otherwise. False positive errors are common in everyday life, sometimes producing bad outcomes. The parent who says “I do not wish my child to be vaccinated against measles because there is a risk of brain damage” is not evaluating the risk involved in contracting measles at a later date. Comparing risks shows that the much higher risk of catching measles with a devastating outcome far outweighs the miniscule risk involved in vaccination. Identifying false positive errors is important in medicine because:
