The following table of male suicide in the Sydney metropolitan area, stratified by quintile of socio-economic status (SES). (Only the lowest and highest SES groups are shown). Note: 5 years of death data are presented. Population data comes from a single census year (2011). It is conventional to present mortality rates as annual average rates.

	Lowest SES quintile, Suicides	Lowest SES quintile, Population	Highest SES quintile, Suicides	Highest SES quintile, Population	Total suicide (All quintiles)	Total population (All quintiles)
	2009-2013	2011	2009-2013	2011	2009-2013	2011
Males
15-24	195	123,961	116	140,942	779	667,548
25-34	242	134,303	158	134,595	1,044	693,988
35-44	204	133,242	123	135,819	865	688,839
45-54	147	110,680	92	124,576	594	577,128
55-64	89	83,943	55	75,308	364	381,248
65-74	76	73,509	42	56,097	283	304,226
75+	56	39,197	43	36,293	224	172,856
	1,009	698,835	629	703,630	4,153	3,485,833

(a) Calculate the crude suicide incidence rate (per 100,000) for the lowest SES quintile and the highest SES quintile for those aged ≥15 years and summarize your findings

(b) Calculate the direct age-standardized suicide incidence rate (per 100,000) for the lowest SES quintile using the highest SES quintile as the standard.

(c) Do you think that age structure is an important factor in explaining the differences in suicide between low and high SES groups? Using the age-specific data you calculated, make a specific comment about the difference between the crude suicide rate and the direct age-standardized suicide rate.