How To Calculate The P Value Of A Test Statistic

Statistical tests play a crucial role in drawing conclusions from data. One essential aspect of these tests is the P value, which indicates the probability of obtaining results as extreme as the ones observed, assuming the null hypothesis is true. In this article, we will explore how to calculate the P value of a test statistic.

Formula: The P value is calculated based on the test statistic and degrees of freedom, using specific statistical distributions. It involves comparing the observed test statistic to the distribution under the null hypothesis.

How to Use:

  1. Enter the test statistic in the designated input field.
  2. Enter the degrees of freedom related to the statistical test.
  3. Click the “Calculate” button to obtain the P value.

Example: Suppose you have a t-test with a test statistic of 2.5 and 10 degrees of freedom. Enter these values, click “Calculate,” and the corresponding P value will be displayed.


  1. Q: What is a P value? A: The P value is a measure that helps assess the evidence against a null hypothesis in statistical hypothesis testing.
  2. Q: Why is the P value important? A: It indicates the probability of observing results as extreme as the ones obtained if the null hypothesis is true.
  3. Q: How is the P value interpreted? A: A smaller P value suggests stronger evidence against the null hypothesis, typically below a significance level (e.g., 0.05).
  4. Q: What does a high P value mean? A: A high P value suggests that the observed results are likely under the null hypothesis, and there is weak evidence against it.
  5. Q: Can the P value be negative? A: No, the P value is always a positive value representing the probability.

Conclusion: Calculating the P value of a test statistic is a crucial step in statistical analysis. Understanding its significance helps researchers make informed decisions about the null hypothesis. Use the provided calculator to streamline this process for various statistical tests.

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