T-Test Calculator
Free T-Test Calculator for one-sample, two-sample, and paired t-tests. Calculate t-statistic, p-value, and confidence intervals with step-by-step results.
Understanding T-Tests
What is a T-Test?
A t-test is a statistical hypothesis test that helps you determine whether there is a significant difference between means. It's one of the most commonly used statistical tests in research, science, and business applications.
The t-test compares your sample data to either a known value or another sample, helping you make informed decisions about whether observed differences are due to chance or represent real effects.
Key Concepts
- •Null Hypothesis (H₀): The assumption that there's no significant difference
- •Alternative Hypothesis (H₁): The claim that there is a significant difference
- •P-value: Probability of observing the data if H₀ is true
- •Significance Level (α): Threshold for rejecting H₀ (typically 0.05)
Types of T-Tests
One-Sample T-Test
Compares a sample mean to a known or hypothesized population mean.
When to use:
- • Testing if a sample differs from a known value
- • Quality control assessments
- • Comparing to industry standards
Example:
"Does our new teaching method produce test scores different from the national average of 75?"
Two-Sample T-Test
Compares means between two independent groups.
When to use:
- • Treatment vs. control groups
- • Comparing two populations
- • A/B testing scenarios
Example:
"Do students using the new study method perform better than those using the traditional method?"
Paired T-Test
Compares means from the same subjects under different conditions.
When to use:
- • Before and after studies
- • Same subjects, different treatments
- • Repeated measures designs
Example:
"Do patients' blood pressure readings change after taking a new medication?"
Related Statistical Tools
T-tests are part of a broader statistical toolkit. Consider these related analyses for your research:
Z-Score Calculator
Convert raw scores to standardized z-scores for normal distribution analysis.
Try Z-Score Calculator →P-Value Calculator
Calculate p-values from z-scores and understand statistical significance.
Try P-Value Calculator →Confidence Interval Calculator
Estimate population parameters with confidence intervals.
Try Confidence Interval Calculator →Z-Table Reference
Look up critical values and probabilities for the standard normal distribution.
View Z-Table →