Question

What measures of association are used to indicate the presence of the public health problem you identified? Discuss each of these measures as they relate to your chosen problem.

Answer 1

The measures of association refer to a wide variety of coefficients that measure the strength and direction of the relationship between variables; these measures of strength, or association, can be described in several ways, depending on the analysis.

A measure of association quantifies the relationship between exposure and disease among the two groups. Exposure is used to mean not only exposure to foods, mosquitoes, a partner with a sexually transmissible disease, or a toxic waste dump, but inherent characteristics of persons, biologic characteristics, acquired characteristics, activities, or conditions under which they live.

The measures of association described to compare disease occurrence among one group with disease occurrence in another group. Examples of measures of association include risk ratio, odds ratio, and proportionate mortality ratio.

A risk ratio also called relative risk, compares the risk of a health event among one group with the risk among another group. It divides the risk in group 1 by the risk in group 2. The two groups are typically differentiated by such demographic factors as sex or by exposure to a suspected risk factor. The group of primary interest is labeled the exposed group, and the comparison group is labeled the unexposed group.

A rate ratio compares the incidence rates, mortality rates of two groups. The risk ratio, the two groups are typically differentiated by demographic factors by exposure to a suspected agent. The rate for the group of primary interest is divided by the rate for the comparison group.

An odds ratio is another measure of association that quantifies the relationship between an exposure with two categories and health outcome. The odds ratio is sometimes called the cross product ratio because the numerator is based on multiplying the value in cell visa vis the value in cell, whereas the denominator is the product of cell.

The odds ratio is the measure of choice in a case control study. A case control study is based on enrolling a group of persons with disease and a comparable group without disease. The number of persons in the control group is decided by the investigator. The size of the population from the case patients came is not known. As a result, risks, rates, risk ratios or rate ratios cannot be calculated from the typical case control study. You need to calculate an odds ratio and interpret it as an approximation of the risk ratio, particularly when the disease is uncommon in the population.