How to Find P-Value on TI-84​?

The TI-84 graphing calculator is a powerful tool for calculating p-values in statistical hypothesis testing. Whether you're using a physical calculator or prefer an online TI-84 calculator, the process remains the same. Let's explore two methods to determine p-values.

Method 1: Using the Inference Test Menu

This method applies when performing hypothesis tests (e.g., t-test or z-test) directly from the calculator’s statistical functions:

  1. Access the Tests Menu:

    • Press the STAT button.
    • Scroll right to select the TESTS menu.

  2. Choose the Appropriate Test:

    • For z-tests, select Z-Test (if population standard deviation is known).
    • For t-tests, select T-Test (if using sample standard deviation).

  3. Input Parameters:

    • Enter the sample mean, hypothesized mean, standard deviation, sample size, and test type (left-tailed, right-tailed, or two-tailed).

  4. Calculate:

    • Select Calculate and press ENTER. The p-value will be displayed alongside other test results.

Pro Tip: Don't have a physical TI-84 calculator? Try our free online TI-84 calculator that works exactly like the real thing - perfect for practicing these calculations or when you're away from your physical calculator.

Method 2: Manual Calculation Using normalcdf

If you already have a z-score, use the normalcdf function to compute the p-value.

  • Left-Tailed Test:
    Syntax: normalcdf(-1E99, z-score, 0, 1)
    Example: For a z-score of -1.34, input normalcdf(-1E99, -1.34, 0, 1) to get a p-value of ≈0.0901.

  • Right-Tailed Test:
    Syntax: normalcdf(z-score, 1E99, 0, 1)
    Example: For a z-score of 2.78, input normalcdf(2.78, 1E99, 0, 1) to get a p-value of ≈0.0027.

  • Two-Tailed Test:
    Syntax: 2 * normalcdf(|z-score|, 1E99, 0, 1)
    Example: For a z-score of 2.31, compute normalcdf(2.31, 1E99, 0, 1) * 2 to get a p-value of ≈0.0209.

Key Notes

  • Use EE for scientific notation (press 2nd then ,).
  • For t-scores, replace normalcdf with tcdf, adjusting degrees of freedom.
  • Always verify whether your test is one-tailed or two-tailed to apply the correct calculation.

Whether you're using a physical TI-84 calculator or our online version, these methods will help you efficiently compute p-values for hypothesis testing. The online calculator is particularly useful for practice and when you need to perform calculations on the go.