1. What is Two Sample Confidence Interval?

The two-sample confidence interval estimates the range of plausible values for the difference between two population means. It helps determine if there's a statistically significant difference between two groups.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( m1 \) — Mean of sample 1
• \( m2 \) — Mean of sample 2
• \( se1 \) — Standard error of sample 1
• \( se2 \) — Standard error of sample 2
• \( t \) — t-value for desired confidence level

Explanation: The interval gives the range within which the true difference in population means is likely to fall, with a specified level of confidence.

3. Importance of Confidence Intervals

Details: Confidence intervals provide more information than p-values alone, showing both the magnitude and precision of an observed effect.

4. Using the Calculator

Tips: Enter the means, standard errors, and appropriate t-value for your desired confidence level. The t-value depends on your degrees of freedom and confidence level (e.g., 1.96 for 95% CI with large samples).

5. Frequently Asked Questions (FAQ)

Q1: When should I use this calculator?
A: Use when comparing means from two independent samples with normally distributed data.

Q2: How do I find the correct t-value?
A: Use a t-table with (n1 + n2 - 2) degrees of freedom at your desired confidence level.

Q3: What if my confidence interval includes zero?
A: If zero is within the interval, there may be no statistically significant difference between groups.

Q4: Can I use this for proportions?
A: No, this formula is for means. Use a different formula for proportion comparisons.

Q5: What assumptions does this method make?
A: Assumes independent samples, normal distributions, and equal variances (unless using Welch's correction).