Measuring health and illness

Calculations are for some specified time period.

1. Calculating a Proportion

• Question: What proportion of all deaths is by those who are white?
• Answer:  20,000 / 34,000  =  0.588 (i.e., 58.5%)

– Note: numerator (whites who died) are included in denominator (total # deaths)

2. Calculating a Ratio

• Question: How do deaths among whites compare to deaths among nonwhites (i.e., what is ratio of white deaths to nonwhite deaths)?
• Answer: 
  • White deaths = 20,000; Nonwhite deaths = 14,000
  • White deaths compared to nonwhite deaths = 20,000 / 14,000  =  1.43

– Interpretation: 1.43 white deaths for every nonwhite death

3. Calculating a Rate

• Question: what is overall mortality rate?
• Answer: Total # deaths = 34,000.  Total population = 345,000,000

– Mortality rate = 34,000 / 345,000,000  =  0.0000986

• Multiply by 1,000 for rate per 1,000 (0.0986 deaths per 1,000 population)
• Multiply by 1,000,000 for rate per 1 million (98.6 deaths per 1 million population)

4. Calculating a Rate

• Question: what is the race-specific mortality rate?
• Answer:

                Among Whites:  20,000 / 220,000,000 = 0.0000909

                Among Nonwhites: 14,000 / 125,000,000 = 0.000112

Mortality rates per million population:

– mortality rate among whites = 90.9  per million

– mortality rate among nonwhites = 112.0 per million