What is case-control study PPT?
Dictionary of Epidemiology: 3rd ed; John M Last. 2000) Case-Control Studies A case control study involves two populations – cases and controls and has three distinct features : Both exposure and outcome have occurred before the start of the study. The study proceeds backwards from effect to cause.
What is an example of a case-control study?
For example, investigators conducted a case-control study to determine if there is an association between colon cancer and a high fat diet. Cases were all confirmed colon cancer cases in North Carolina in 2010. Controls were a sample of North Carolina residents without colon cancer. The odds ratio was 4.0.
What is case-control study design PDF?
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).
What are the steps of case-control study?
Five steps in conducting a case-control study
- Define a study population (source of cases and controls)
- Define and select cases.
- Define and select controls.
- Measure exposure.
- Estimate disease risk associated with exposure.
- Confounding factors.
- Matching.
- Bias.
What is the difference between cohort study and case-control study?
Whereas the cohort study is concerned with frequency of disease in exposed and non-exposed individuals, the case-control study is concerned with the frequency and amount of exposure in subjects with a specific disease (cases) and people without the disease (controls).
What is meta analysis in research PPT?
DEFINITION Meta-analysis is a quantitative approach for systematically combining results of previous research to arrive at conclusions about the body of research.
Which type of study is a case-control study?
How many controls are in a case-control study?
Investigators planning case-control studies are usual- ly advised to include no more than four or five controls per case because little statistical power is gained by fur- ther increasing this ratio (1,2).
How do you select cases in 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.
How do you calculate sample size for a case-control study?
In case control studies, we usually calculate the odds ratio, if you are also planning to do so, your required sample size can be calculated by just putting in the values of Expected proportion exposed in controls and assumed odds ratio into the site above (link given).
When would you use a case-control study?
Case-control studies are advantageous under the following circumstances: When exposure data are expensive or difficult to obtain, e.g., assessing pesticide levels in blood or other medical tests. When the disease has a long induction and/or latent period, e.g., cancer, dementia.
What is Metaverse PPT?
Metaverse PowerPoint Template is a collection of attractive layouts and graphics to showcase metaverse projects and concepts. This template features a deep blue background and 3D shapes, which illustrate the idea of digital and cyberspace.
What is an example of a meta-analysis?
For example, if there are two groups of patients experiencing different treatment effects studies in two randomised control trials (RCTs) reporting conflicting results, the meta-analytic average is representative of neither group, similarly to averaging the weight of apples and oranges, which is neither accurate for …
Who are the subjects in a case-control study?
In a case-control study, 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). The investigator then assesses the exposure in both these groups.
How many controls are in a case?
What is a good sample size?
A good maximum sample size is usually 10% as long as it does not exceed 1000. A good maximum sample size is usually around 10% of the population, as long as this does not exceed 1000. For example, in a population of 5000, 10% would be 500. In a population of 200,000, 10% would be 20,000.
What is a minimum sample size?
Your minimum sample size is the minimum number of respondents you need to get survey results that reflect the population you are studying, whilst adhering to your desired confidence interval (margin of error) and confidence level.
What are 2 limitations of case-control studies?
The main limitations of case-control studies are:
- ‘Recall bias’ When people answer questions about their previous exposure to certain risk factors their ability to recall may be unreliable.
- Cause and effect.
- ‘Sampling bias’
- Other limitations.
What are the 7 layers of metaverse?
What Are the Seven Layers of the Metaverse?
- The experience layer.
- The discovery layer.
- The creator economy.
- The spatial computing layer.
- The decentralization layer.
- The human interface layer.
- The infrastructure layer.
What is virtual reality PPT?
Virtual Reality means feeling the imaginary(virtual) world, rather than the real one. The imaginary world is a simulation running in a computer. Virtual reality is the term used for computer generated 3D environments that allow the user to enter and interact with alternate realities.
What is meta-analysis PPT?
1. META ANALYSIS – AN OVERVIEW Tulasi Raman P. DEFINITION Meta-analysis is a quantitative approach for systematically combining results of previous research to arrive at conclusions about the body of research.
Is a systematic review qualitative or quantitative?
A systematic review can be either quantitative or qualitative. A quantitative systematic review will include studies that have numerical data. A qualitative systematic review derives data from observation, interviews, or verbal interactions and focuses on the meanings and interpretations of the participants.
How do you choose controls for a case-control study?
What is the best ratio for case and control study?
Additional Points in A Case-Control Study
The most optimum case-to-control ratio is 1:1. Jewell (2004) has suggested that for a fixed sample size, the chi square test for independence is most powerful if the number of cases is same as the number of controls.
Why is 30 the minimum sample size?
A sample size of 30 often increases the confidence interval of your population data set enough to warrant assertions against your findings. 4 The higher your sample size, the more likely the sample will be representative of your population set.