What are matched controls?
What are matched controls?
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.
What are matched control subjects?
Matching is not uncommon in epidemiological studies and refers to the selection of unexposed subjects’ i.e., controls that in certain important characteristics are identical to cases. Generally, to match controls with cases is an often applied device to control for confounding in studies.
What is a matched cohort study?
A matched cohort study involves pairs (or clusters in case several untreated subjects are matched with each of the treated individuals) formed to include individuals who differ with respect to treatment but may be matched on certain baseline characteristics.
What are the benefits of matching in a case-control study?
Firstly, matching in case-control studies ensures that the matching factors, such as age or sex, are equally distributed between cases and controls. Although matching thus removes the original confounding effect of these factors, it may introduce a new bias.
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.
How do you match a case-control study?
In a matched study, we enroll controls based upon some characteristic(s) of the case. For example, we might match the sex of the control to the sex of the case. The idea in matching is to match upon a potential confounding variable in order to remove the confounding effect.
How do you select controls for a case-control study?
Selection of the Controls
- The comparison group (“controls”) should be representative of the source population that produced the cases.
- 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 matched studies?
Matching (or pairing) is commonly used in study designs as a means of controlling for variability. It is especially common in case-control designs where each case is matched to one (or more) controls. Matching is most frequently done for age, but may be done for any potentially confounding factor.
What is unmatched case control in research?
Unmatched Case-Control. 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 the difference between “matched” and “unmatched” studies?
Statistical analysis “Matched” vs. “Unmatched” studies The procedures for analyzing the results of case-control studies differ depending on whether the cases and controls are matched or unmatched. Matched Unmatched ・McNemar’s test ・Chi-square test ・Conditional logistic ・Unconditional logistic regression analysis regression analysis
How do I calculate a sample size for an unmatched case-control?
The following example demonstrates how to calculate a sample size for an unmatched case- control study. The application will show three different sample size estimates according to three different statistical calculations. From the Epi Info™ main page, select StatCalc. Select Unmatched Case-Control. The Unmatched Case-Control window opens.
How do I use unmatched case-control in Epi Info™?
From the Epi Info™ main page, select StatCalc. Select Unmatched Case-Control. The Unmatched Case-Control window opens. Select the Two-sided confidence level of 95% from the drop-down list. Enter the desired Power (80%) to detect a group difference at that confidence level. Enter the ratio of controls to cases as 3.
