Based on these SMRs alone, it is possible to conclude that: a. The number of deaths from lung cancer in carpenters in 1949–1960 was greater than the number of deaths from lung cancer in bricklayers during the same period b. The proportionate mortality from lung cancer in bricklayers in 1949–1960 was greater than the proportionate mortality from lung cancer in the same occupational group in 1968–1979 c. The age-adjusted rate of death from lung cancer in bricklayers was greater in 1949– 1960 than it was in 1968–1979 d. The rate of death from lung cancer in carpenters in 1968–1979 was greater than would have been expected for a group of men of similar ages in all occupations e. The proportionate mortality rate from lung cancer in carpenters in 1968–1979 was 1.35 times greater than would have been expected for a group of men of similar

d. The rate of death from lung cancer in carpenters in 1968–1979 was greater than would have been expected for a group of men of similar ages in all occupations

Explanation:

SMRs - Standardized mortality ratios are useful for measuring whether a population, made-up of workers in a certain industry, has higher mortality than what would be expected if the population had the same mortality rate as those in the general population.

SMRs = (observed number of deaths) / (expected number of deaths.)

This tool is used as an indirect method to adjust age expectation.

To draw inferences, when the ratio of SMRs is greater than 1 (or 100 when multiplied by this amount to remove the decimal).

This shows that the occupational demographic grouping has a higher mortality rate than what would be expected for a similar group of people of differing ages who are representative of a series of occupations, not just carpentry.

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.