Lower 95 Confidence Interval Calculator
Expert Guide to Lower 95 Confidence Intervals
Introduction & Importance
Lower 95 confidence intervals are a statistical measure used to estimate the range within which a population parameter falls with 95% confidence. They are crucial in understanding the reliability of sample estimates and making data-driven decisions.
How to Use This Calculator
- Enter your sample size, mean, and standard deviation.
- Click ‘Calculate’.
- View the results and chart below.
Formula & Methodology
The formula for a lower 95 confidence interval is:
Mean - (Z * Standard Deviation / √Sample Size)
Where Z is the Z-score for a 95% confidence interval, approximately 1.645.
Real-World Examples
Case Study 1: IQ Scores
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Case Study 2: Customer Satisfaction
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Case Study 3: Height of Adults
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Data & Statistics
| Sample Size | Lower 95 CI | Lower 99 CI |
|---|---|---|
| 30 | … | … |
| 100 | … | … |
Expert Tips
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Interactive FAQ
What is a confidence interval?
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How do I interpret the results?
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What if my data is not normally distributed?
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Office for National Statistics – A reliable source for statistical data.
Centers for Disease Control and Prevention – Providing credible health information.