What is an unmatched case-control study?
The Unmatched Case-Control study calculates the sample size recommended for a study given a set of parameters and the desired confidence level.
What is an unmatched study?
In an unmatched case-control study of a binary exposure, in which the expected odds ratio deviates from the null (i.e., no effect) and the sum of the number of cases and controls is fixed, 1:1 sampling of cases and controls may yield suboptimal statistical efficiency.
What is matched control?
noun. Statistics. (More fully “matched control group”) a control group of individuals selected to resemble an experimental group in all properties except the one under investigation.
What is matched and unmatched case-control?
Abstract. Multiple control groups in case-control studies are used to control for different sources of confounding. For example, cases can be contrasted with matched controls to adjust for multiple genetic or unknown lifestyle factors and simultaneously contrasted with an unmatched population-based control group.
When an odds ratio is calculated from a 2×2 table?
If the data is set up in a 2 x 2 table as shown in the figure then the odds ratio is (a/b) / (c/d) = ad/bc. The following is an example to demonstrate calculating the odds ratio (OR).
What is matched and unmatched case control?
When would you use a matched case control study?
The Matched Pair Case-Control Study calculates the statistical relationship between exposures and the likelihood of becoming ill in a given patient population. This study is used to investigate a cause of an illness by selecting a non-ill person as the control and matching the control to a case.
Does matching control for confounding?
Matching is a technique used to avoid confounding in a study design. In a cohort study this is done by ensuring an equal distribution among exposed and unexposed of the variables believed to be confounding. Nonetheless, a matched case-control study is suitable for confounders that are difficult to measure.
Does matching introduce bias?
Rothman and Greenland (1998) go on to say that while matching is intended to control confounding, it cannot do this in case-control study designs, and can, in fact, introduce bias. Matched sampling leads to a balanced number of cases and controls across the levels of the selected matching variables.
What are matched cases?
2.1. In an individually matched case-control study, the population of interest is identified, and cases are randomly sampled or selected based on particular inclusion criteria. Each of these cases is then matched to one or more controls based on a variable (or variables) believed to be a confounder.