What Are the Chances?

In the real world, unlike cartoons, anvils don't plummet from the sky unexpectedly. We don't anticipate bricks, bullets, or anything other than rain or snow falling on us. No one we know has ever been hit by a falling anvil, and we have no experience with the Acme product line. Thus, being struck by an anvil would likely be seen as a bizarre, unforeseeable accident—an act of fate or sheer misfortune.

Freak accidents and acts of God are typically viewed as rare occurrences that are impossible to foresee, control, or avoid. For instance, what are the odds of being hit by a bullet that was shot straight into the air? Let's analyze the possibilities.

What goes up must come down, correct? When a bullet is fired from a Kalashnikov rifle, it exits the barrel at over 1,500 miles per hour (2,414 kilometers per hour). If shot vertically, it slows to about 150 miles per hour (241.4 kilometers per hour) due to air resistance before hitting the ground—or potentially your head—with the force of a brick or anvil falling from 4 feet (1.2 meters) [source: Matthews]. Bullets falling at 68 mph (109.4 kilometers per hour) can pierce the skin, while those at 136 mph (218.9 kilometers per hour) may fracture bones or cause fatal injuries [source: Maugh]. The chance of experiencing an accidental firearm injury in your lifetime? Nearly 1 in 6,000 [source: National Center for Health Statistics].

Avoiding bullets isn’t your only worry. Other rare dangers include being struck by lightning (1 in 10,000 lifetime odds), hit by a meteorite (1 in 700,000), or injured by a vending machine (which claims a few victims annually). Events like Hurricane Katrina and other natural disasters also fall into the category of freak accidents [sources: NOAA, Plait]. Curious about your odds of amusement park injuries? We’ll reveal those numbers next, along with how experts calculate such risks.

Probability, Odds and Risk Assessment

Discussing the likelihood of freak accidents involves understanding probability, odds, and risk assessment.

Probability refers to the ratio of favorable outcomes to total possible outcomes. For example, flipping a coin yields two possible results—heads or tails—with a 1 in 2 chance of landing on your chosen side. Odds, however, compare favorable outcomes to unfavorable ones. In a coin toss, the odds are 1 to 1. While it may seem complex, we use these concepts daily, such as interpreting weather forecasts. Risk assessment involves evaluating the likelihood of an event (e.g., a 50% chance of rain) and its potential impact (e.g., carrying an umbrella).

The National Safety Council, a non-profit dedicated to reducing preventable injuries and deaths, employs these calculations to determine the probability of various events harming the public. They, along with other organizations, evaluate the odds of death by cause or event over two timeframes: annually and over a lifetime. Let’s explore how they calculate these odds, using amusement park injuries as an example.

The Likelihood

To assess the risk of a freak accident occurring in a single year, you require two figures: the population for that year and the number of deaths caused by that specific event. For instance, what’s the likelihood of being injured at an amusement park?

In 2009, approximately 280 million Americans visited amusement parks, representing the park population. That same year, 1,086 park-related accidents were reported. Dividing the number of visitors by the number of injuries reveals a 1 in 257,826 chance of being injured at an amusement park in a single year.

To determine the lifetime risk of such an injury, take the one-year probability we calculated and divide it by the average life expectancy for someone born in that year—2009, in this case. In 2009, the chance of an amusement park injury was 1 in 257,826. With a life expectancy of 78.5 years, dividing 257,826 by 78.5 results in a lifetime odds of 1 in 3,284 for being injured at an amusement park [source: IAAPA, CDC].

The likelihood of experiencing a freak accident isn’t as straightforward as these numbers suggest. Consider this: While fatal car accidents are more common than shark attacks, far more people drive than swim in shark-infested waters. For instance, if you live in Wichita, Kansas, you’re roughly 1,400 miles (2,253 kilometers) from both Venice Beach, California, and Venice, Florida. If your vacations take you less than 1,200 miles (1,931.2 kilometers) from home—as most Americans’ do—your risk of a shark encounter, or even seeing the ocean, is far lower than someone surfing in California’s Red Triangle, a hotspot for shark activity. Location plays a key role in risk reduction.

While you can’t predict or prevent every potential injury or death caused by natural events (or even a neighbor’s trampoline), you can take steps to reduce your risk of premature death from chronic illnesses like heart disease, diabetes, and cancer. Quit smoking, exercise for at least 30 minutes daily, maintain a healthy diet—and, for safety’s sake, avoid rocking or tilting vending machines to free a stuck snack.