Measures of Association Question 20

Question

a. You want to compare cancer mortality rates in the United States between 1980 and 1940. You know that cancer is associated with age and that the age distribution of the U.S. population has changed between 1940 and 1980. Which rates would be best to compare: crude or age-standardized? Why?

b. Calculate the crude mortality rates for populations A and B. Which population appears healthier?

	Population A			Population B
Age	Deaths (years)	Population (size)	Rate (A)	Deaths	Population	Rate (A)
0‑4	80	22,000		400	100,000
5‑19	97	85,000		340	290,000
20‑44	140	100,000		300	300,000
45‑64	350	70,000		850	170,000
65+	600	31,000		1,400	80,000
Total	1,267	308,000		3,290	940,000

Total

1,267

308,000

3,290

940,000

c. Calculate the age‑specific mortality rates for populations A and B. How do they compare?

	Population A			Population B
Age	Deaths	Population	Rate (A)	Deaths	Population	Rate (B)
0‑4	80	22,000		400	100,000
5‑19	97	85,000		340	290,000
20‑44	140	100,000		300	300,000
45‑64	350	70,000		850	170,000
65+	600	31,000		1,400	80,000
Total	1,267	308,000		3,290	940,000

	Population A			Population B
Age	Deaths	Population	Rate (A)	Deaths	Population	Rate (B)
0‑4	80	22,000		400	100,000
5‑19	97	85,000		340	290,000
20‑44	140	100,000		300	300,000
45‑64	350	70,000		850	170,000
65+	600	31,000		1,400	80,000
Total	1,267	308,000		3,290	940,000

d. Determine the expected number of deaths by age group using the U.S. Census Population from 1970 as your standard population.

Age (yrs)	U.S. 1970 Population size	Population A Rate	Expected Deaths	Population B Rate	Expected Deaths
0‑4	9,500	0.004		0.004
5‑19	22,000	0.001		0.001
20‑44	41,000	0.001		0.001
45‑64	30,000	0.005		0.005
65+	10,000	0.019		0.018
Total	198,000

e.  What are the age‑adjusted total rates for populations A and B?  Which population is healthier?

Link to Measures of Association Answers