How to find p value from z score on ti 84 plus

How to find p value from z score on ti 84 plus

The Correct Answer and Explanation is:

To find the p-value from a z-score using the TI-84 Plus calculator, you can follow these steps:

Step-by-Step Guide:

1. Turn on the calculator: Press the ON button.
2. Access the Distribution Menu:

• Press the 2nd button, then VARS to access the DISTR menu.

1. Select the Normalcdf Function:

• For a one-tailed test (if your z-score is positive), scroll down and select normalcdf(.
• If your z-score is negative or you need a two-tailed test, you may use normalcdf for each side separately.

1. Input the Parameters:

• The syntax for normalcdf is: normalcdf(lower bound, upper bound, mean, standard deviation).
• Since you’re working with z-scores (where the mean = 0 and standard deviation = 1), the parameters will be:
  • For a right-tailed test: Input normalcdf(z, 1E99, 0, 1) where z is your z-score. The 1E99 represents a very large upper bound.
  • For a left-tailed test: Input normalcdf(-1E99, z, 0, 1).
  • For a two-tailed test: Calculate both tails: for z > 0: normalcdf(-1E99, -|z|, 0, 1) + normalcdf(z, 1E99, 0, 1).

1. Press Enter: After entering the parameters, press ENTER to compute the p-value.

Example:

Suppose you have a z-score of 1.96. For a right-tailed test:

• Input: normalcdf(1.96, 1E99, 0, 1).
• The calculator will return a p-value, which in this case is approximately 0.025.

Understanding the p-value:

The p-value represents the probability of obtaining a test statistic at least as extreme as the one observed, assuming the null hypothesis is true. A small p-value (typically ≤ 0.05) indicates strong evidence against the null hypothesis, leading to its rejection. Conversely, a large p-value suggests insufficient evidence to reject the null hypothesis. Thus, the p-value helps determine statistical significance in hypothesis testing, guiding researchers in making informed decisions based on their data.