What measure of association is used in a case-control study?

The odds ratio
The odds ratio is the “measure of association” for a case-control study. It quantifies the relationship between an exposure (such as eating a food or attending an event) and a disease in a case-control study.

What are the measures of association?

Examples of measures of association include risk ratio (relative risk), rate ratio, odds ratio, and proportionate mortality ratio.

How do you conduct a case-control study?

Five steps in conducting a case-control study

1. Define a study population (source of cases and controls)
2. Define and select cases.
3. Define and select controls.
4. Measure exposure.
5. Estimate disease risk associated with exposure.
6. Confounding factors.
7. Matching.
8. Bias.

How do you select controls for a case-control study?

Selection of the Controls

1. The comparison group (“controls”) should be representative of the source population that produced the cases.
2. The “controls” must be sampled in a way that is independent of the exposure, meaning that their selection should not be more (or less) likely if they have the exposure of interest.

What are absolute measures of association?

Absolute Measures of Association The risk difference is the risk of the outcome among treated subjects minus the risk of the outcome among untreated subjects and is typically expressed as a percentage. For the cohort study example, this is 71/121 – 117/183 = –0.053 = –5.3% (table 2b).

What is the degree of association between variables?

The correlation coefficient is a measure of the degree of linear association between two continuous variables, i.e. when plotted together, how close to a straight line is the scatter of points. The standard method (often ascribed to Pearson) leads to a statistic called r, Pearson’s correlation coefficient.

What is the primary purpose of controls in a case-control study?

A case-control study is designed to help determine if an exposure is associated with an outcome (i.e., disease or condition of interest). In theory, the case-control study can be described simply. First, identify the cases (a group known to have the outcome) and the controls (a group known to be free of the outcome).

What are absolute measures?

a measurement made directly and independently of comparison with other measurements. An absolute measurement of an individual’s height, for instance, would yield a single definitive value that need not be assessed relative to another person to be meaningful. Compare relative measurement.

What are measures of effect?

The ‘measures of effect’ are indexes that summarize the strength of the link between exposures and outcomes and can help the clinician in taking decisions in every day clinical practice. The risk ratio, the incidence rate ratio, and the odds ratio are relative measures of effect.

What type of study is a case-control study?

Case-Control study design is a type of observational study. In this design, participants are selected for the study based on their outcome status. Thus, some participants have the outcome of interest (referred to as cases), whereas others do not have the outcome of interest (referred to as controls).

Which is a measure of Association in a case control study?

Calculating Measures of Association Case-control studies The odds ratio is the measure of association for a case-control study. It tells us how much higher the odds of exposure is among cases of a disease compared with controls.

How to calculate incidence in a case control study?

Key Concept:Remember that in a cohort studyyou can calculate either a risk ratio or an odds ratio, but In a case-control study: you can only calculate an odds ratio. Incidence is Unknown in a Case-Control Study In a cohort type study, one can calculate the incidence in each group, the risk ratio, the risk difference, and the attributable fraction.

How to estimate the appropriate measure of association?

In this module, you will learn the key elements of case-control study design, and you will learn how to estimate the appropriate measure of association when presented with data from a case-control study. In the case control study you begin with the outcome of interest and then estimate exposure.

Is the odds ratio in a case control study meaningful?

An odds ratio without a confidence interval is not very meaningful. These calculations are usually made with computer programmes (e.g., Epi-Info). Case-control studies cannot provide any information about the incidence or prevalence of a disease because no measurements are made in a population based sample.