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Appendix Two: Understanding and Using Statistics

Risk

Risk is a commonly-used term in health-related statistics to describe the possibility of illness, injury, or death.

There are several ways to measure the risk of firearms injury and death.

Rates

The most common tool for measuring the risk of firearms violence is the rate. Rates related to gun violence are most commonly expressed as a number of deaths or injuries per 100,000 people (although they are sometimes expressed as another multiple of 10 such as: per 100; per 1000; per 10,000; or, per 1,000,000 people). For example:

In 1995 the U.S. rate of firearms homicide was 6.0 per 100,000.

This means that in 1995 six out of every 100,000 Americans died in firearm-related homicides.

The way to derive a rate is to take the number of deaths or injuries from guns in a group of people, divide by the total population of people in that group, and multiply by the number that will best express the risk. For example, to obtain the overall U.S. rate of firearm homicides:

(Number of firearm homicides in the U.S. in 1995 divided by population of U.S. in 1995) X 100,000 = Rate per 100,000.

Sometimes firearm-related death rates are age-specific. Age-specific rates are deaths per 100,000 population in a specified age group, such as 10 to 14 years of age or 15 to 24 years of age for a specified period. For example:

In 1995 the U.S. rate of firearms homicide among people aged 15 to 24 was 17.0 per 100,000.

Age-specific rates are very useful for describing the risk of gun violence because death and injury from guns is not consistent across the lifespan. As illustrated above, the age-specific rate of firearms homicide for people aged 15 to 24 is much higher than the overall U.S. rate. This means that people aged 15 to 24 are nearly three times as likely to be victims of firearms homicide than the overall U.S. population. To obtain the U.S. rate of firearm homicides among people aged 15 to 24:

(Number of firearm homicides in the U.S. among people aged 15 to 24 in 1995 divided by population of people aged 15 to 24 in the U.S. in 1995) X 100,000 = Rate per 100,000.

Sometimes the rate is higher for one group than another even though the actual number of deaths or injuries is smaller. For example:

In 1995 there were 8,494 African-American males and 21,510 white males killed by firearms in the United States. In 1995 the U.S. firearm-related death rate among African-American males was 54.0 per 100,000 while the firearm-related death rate of white males was 20.1 per 100,000.

Even though the number of deaths was higher among white males, the rate of firearms death was higher among African-American males. The higher firearms death rate among African-American males means that in 1995 more African-American males per 100,000 African-American males in the population were killed with guns than white males per 100,000 white males in the population. This is because the population of African-American males is much lower than white males (15.7 million versus 107.1 million in 1995). African-American males were more than two-and-a-half times as likely (54.0 versus 20.1 per 100,000) to be shot and killed than white males. As this example illustrates, the number of firearm deaths is not as accurate a measure of risk as the rate of firearms death. Comparing rates (e.g. males versus females, youth aged 15 to 19 versus the overall population) is the most accurate way to describe the impact of gun violence on various groups of people.

Proportions

The second most common statistical tool for measuring the impact of firearms violence is a proportion. A proportion is expressed as a percentage of people affected by a variable out of a larger group. For example:

In 1995, 69 percent of all Americans who died in homicides were killed with firearms.

To calculate this proportion, take the number of people who died in homicides that were killed with firearms and divide by the number of people who died in homicides.

(15,835 firearm-related homicides divided by 22,895 overall homicides) = .69 x 100 = 69 percent


Where did you get that?

   Five Publications Every
   Advocate Needs

   Firearms Violence - General
   Firearms Homicide
   Firearms Homicide and
   Domestic Violence
   Firearms Homicide in
   the Workplace
   Firearms Suicide

   Suicide Among Older
   Americans

   Unintentional Firearm-Related
   Deaths
   Nonfatal Firearm-Related Injuries
   Costs of Firearms Violence
   Firearms and Crime
   Firearms Ownership,
   Concealed Carrying, and
   Self-Defense Use
   Firearms Industry - General
   Licensed Dealers

   Marketing Firearms to
   Women and Youth

   Appendix One: Groups
   and Organizations

   Appendix Two: Understanding
   and Using Statistics






All contents � 1998 Violence Policy Center