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Absolute Risk Difference Formula:
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Absolute Risk Difference (ARD) is a measure of the difference in risk between two groups - typically a control group and an experimental group. It represents the absolute change in risk resulting from an intervention or exposure.
The calculator uses the Absolute Risk Difference formula:
Where:
Explanation: The formula calculates the absolute difference in event rates between the control and experimental groups, providing a direct measure of treatment effect.
Details: ARD is crucial in clinical research and epidemiology for understanding the absolute benefit or harm of interventions. It helps in clinical decision-making and risk-benefit analysis.
Tips: Enter both Control Event Rate (CER) and Experimental Event Rate (EER) as fractions between 0 and 1. For example, 15% should be entered as 0.15.
Q1: What does a positive ARD value indicate?
A: A positive ARD indicates that the control group has a higher event rate than the experimental group, suggesting the intervention may be beneficial.
Q2: What does a negative ARD value indicate?
A: A negative ARD indicates that the experimental group has a higher event rate than the control group, suggesting potential harm from the intervention.
Q3: How is ARD different from Relative Risk?
A: ARD provides the absolute difference in risk, while Relative Risk provides the ratio of risks. ARD is often more clinically meaningful for decision-making.
Q4: When should ARD be used?
A: ARD is particularly useful when the baseline risk is high and absolute benefits or harms need to be communicated clearly to patients and clinicians.
Q5: What are the limitations of ARD?
A: ARD doesn't account for the magnitude of baseline risk and may be less informative when comparing interventions across different populations with varying baseline risks.