1. What is P Value?

The p-value is the probability of obtaining test results at least as extreme as the observed results, assuming the null hypothesis is true. It helps determine statistical significance in hypothesis testing.

2. How Does the Calculator Work?

The calculator uses the t-distribution to calculate the p-value:

Where:

• \( t \) — The calculated t-value from your test
• \( df \) — Degrees of freedom
• \( \text{CDF} \) — Cumulative distribution function of the t-distribution

Explanation: The formula calculates the two-tailed p-value by finding the area under the t-distribution curve beyond the observed t-value.

3. Importance of P Value

Details: P-values help researchers determine whether to reject the null hypothesis. A small p-value (typically ≤ 0.05) indicates strong evidence against the null hypothesis.

4. Using the Calculator

Tips: Enter the t-value from your statistical test and the degrees of freedom. The calculator will compute the two-tailed p-value.

5. Frequently Asked Questions (FAQ)

Q1: What is a good p-value?
A: Typically, p ≤ 0.05 is considered statistically significant, but this threshold depends on your field of study and specific research context.

Q2: What's the difference between one-tailed and two-tailed p-values?
A: One-tailed tests look for an effect in one direction, while two-tailed tests look for an effect in either direction. This calculator provides two-tailed p-values.

Q3: How do I find degrees of freedom?
A: For a t-test, df = n₁ + n₂ - 2 (for two-sample) or n - 1 (for one-sample), where n is sample size.

Q4: What if my p-value is exactly 0.05?
A: This is at the conventional threshold for significance. Consider the context, effect size, and whether you should adjust for multiple comparisons.

Q5: Can I get one-tailed p-values with this calculator?
A: For one-tailed p-value, divide the result by 2 (but only if the direction of your effect matches your hypothesis).