T-Test Formula:
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The t-test is a statistical hypothesis test used to determine if there is a significant difference between the means of two groups. It helps researchers assess whether observed differences between groups are statistically significant or due to random chance.
The calculator uses the t-test formula:
Where:
Explanation: The formula calculates the t-statistic by comparing the difference between group means to the variability within the groups, normalized by sample sizes.
Details: T-test calculation is essential for determining statistical significance in research studies, clinical trials, and experimental designs where comparing two group means is necessary.
Tips: Enter both group means, the pooled standard deviation, and sample sizes for both groups. Ensure all values are valid (standard deviation > 0, sample sizes ≥ 1).
Q1: When should I use a t-test?
A: Use a t-test when you want to compare the means of two independent groups and determine if the difference between them is statistically significant.
Q2: What is a pooled standard deviation?
A: Pooled standard deviation is a weighted average of the standard deviations from both groups, providing a combined measure of variability.
Q3: How do I interpret the t-statistic?
A: A larger absolute t-value indicates a greater difference between groups relative to the variability within groups. Compare it to critical t-values from t-distribution tables.
Q4: What are the assumptions of the t-test?
A: The test assumes normally distributed data, homogeneity of variances, and independent observations between groups.
Q5: What's the difference between one-tailed and two-tailed tests?
A: One-tailed tests check for difference in one direction only, while two-tailed tests check for difference in either direction. Two-tailed is more conservative.