How to Use the Calculator
- Enter the total number of participants in the experimental group and the number of events (e.g., disease occurrence) in that group.
- Enter the total number of participants in the control group and the number of events in that group.
- Click the "Calculate" button to compute the Experimental Event Rate, Control Event Rate, Absolute Risk Reduction (ARR), Relative Risk Reduction (RRR), and Number Needed to Treat (NNT).
- Use the results to compare the effectiveness of the experimental treatment or intervention.
Working Principle
The Experimental Event Rate Calculator helps researchers and clinicians evaluate the effectiveness of interventions by comparing the event rates between an experimental group and a control group. Key metrics include:
- Experimental Event Rate: The proportion of events in the experimental group.
- Control Event Rate: The proportion of events in the control group.
- Absolute Risk Reduction (ARR): The absolute difference in event rates between the two groups. A positive ARR indicates a reduction in risk with the experimental treatment.
- Relative Risk Reduction (RRR): The relative reduction in event rates. A positive RRR indicates a proportional reduction in risk.
- Number Needed to Treat (NNT): The number of patients who need to be treated to prevent one additional event. A lower NNT indicates a more effective treatment.
Example
Suppose a study has 100 participants in the experimental group, with 20 events, and 100 participants in the control group, with 30 events:
- Experimental Event Rate = 20 / 100 = 0.20
- Control Event Rate = 30 / 100 = 0.30
- ARR = 0.20 - 0.30 = -0.10
- RRR = -0.10 / 0.30 = -0.333 (or -33.3%)
- NNT = 1 / -0.10 = -10 (This would be interpreted as the experimental treatment increases risk)