Question
how do you compute the P value for a left tailed test on the TI-84 calculator
Answers
GPT-4o mini
To compute the p-value for a left-tailed test on a TI-84 calculator, follow these steps:
1. **Determine Your Test Statistic**: Before you can calculate the p-value, you need the value of your test statistic (e.g., z-score or t-score). This is typically based on your sample data and the hypothesis you are testing.
2. **Access the Distribution Menu**:
- Turn on your TI-84 calculator.
- Press the `2nd` button.
- Then press the `VARS` button to access the distribution menu.
3. **Choose the Correct Distribution**:
- If you're conducting a z-test (for a normal distribution), scroll down and select `normalcdf(`. If it's a t-test (for a t-distribution), choose `tcdf(`.
- The syntax differs slightly between the two functions.
4. **Input the Parameters**:
- For a **z-test** (using `normalcdf`):
- Syntax: `normalcdf(lower bound, upper bound, mean, standard deviation)`
- For a left-tailed test, input:
- Lower bound: A very small number (like -1E99)
- Upper bound: Your z-score (test statistic)
- Mean: 0
- Standard deviation: 1
- Example: If your z-score is -1.5, you would enter `normalcdf(-1E99, -1.5, 0, 1)`.
- For a **t-test** (using `tcdf`):
- Syntax: `tcdf(lower bound, upper bound, degrees of freedom)`
- Again, for a left-tailed test:
- Lower bound: A very small number (like -1E99)
- Upper bound: Your t-score (test statistic)
- Degrees of freedom: The number of degrees of freedom for your test
- Example: If your t-score is -2.1 and you have 10 degrees of freedom, you would enter `tcdf(-1E99, -2.1, 10)`.
5. **Calculate the p-value**: After inputting the correct parameters, press `ENTER`. The result displayed will be your p-value for the left-tailed test.
6. **Interpret the Result**: Compare the p-value you obtained with your significance level (commonly 0.05 or 0.01) to determine whether to reject the null hypothesis.
Following these steps will help you accurately compute the p-value for a left-tailed test on a TI-84 calculator.
1. **Determine Your Test Statistic**: Before you can calculate the p-value, you need the value of your test statistic (e.g., z-score or t-score). This is typically based on your sample data and the hypothesis you are testing.
2. **Access the Distribution Menu**:
- Turn on your TI-84 calculator.
- Press the `2nd` button.
- Then press the `VARS` button to access the distribution menu.
3. **Choose the Correct Distribution**:
- If you're conducting a z-test (for a normal distribution), scroll down and select `normalcdf(`. If it's a t-test (for a t-distribution), choose `tcdf(`.
- The syntax differs slightly between the two functions.
4. **Input the Parameters**:
- For a **z-test** (using `normalcdf`):
- Syntax: `normalcdf(lower bound, upper bound, mean, standard deviation)`
- For a left-tailed test, input:
- Lower bound: A very small number (like -1E99)
- Upper bound: Your z-score (test statistic)
- Mean: 0
- Standard deviation: 1
- Example: If your z-score is -1.5, you would enter `normalcdf(-1E99, -1.5, 0, 1)`.
- For a **t-test** (using `tcdf`):
- Syntax: `tcdf(lower bound, upper bound, degrees of freedom)`
- Again, for a left-tailed test:
- Lower bound: A very small number (like -1E99)
- Upper bound: Your t-score (test statistic)
- Degrees of freedom: The number of degrees of freedom for your test
- Example: If your t-score is -2.1 and you have 10 degrees of freedom, you would enter `tcdf(-1E99, -2.1, 10)`.
5. **Calculate the p-value**: After inputting the correct parameters, press `ENTER`. The result displayed will be your p-value for the left-tailed test.
6. **Interpret the Result**: Compare the p-value you obtained with your significance level (commonly 0.05 or 0.01) to determine whether to reject the null hypothesis.
Following these steps will help you accurately compute the p-value for a left-tailed test on a TI-84 calculator.