How to Calculate Variance on the TI-84 Plus
Calculating variance on the TI-84 Plus Family of graphing calculators involves following these steps:
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Enter the dataset:
Press the "STAT" button located on the calculator.
Enter each data point of the dataset into the calculator, one at a time, followed by pressing the "ENTER" key after each entry.
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Access the statistical menu:
Press the "2nd" key followed by the "QUIT" key to exit the data entry screen and return to the home screen.
Press the "STAT" button again to access the statistical menu.
Scroll right to reveal the "CALC" menu and press "ENTER" to access it.
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Select the dataset:
Choose "1: 1-Var Stats" from the options displayed in the "CALC" menu and press "ENTER".
Ensure that the correct list containing the dataset is selected (e.g., "L1") and press "ENTER".
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Calculate the sample variance:
Press the "VARS" button located on the calculator.
Scroll down to the "Statistics" submenu and select option "5: variance(" by pressing the corresponding number and then "ENTER".
Press the "X²" key followed by the "ENTER" key to execute the sample variance calculation.
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View the sample variance:
The calculated sample variance (Sx²) will be displayed on the calculator screen.
To calculate the population variance (sx²), perform a 1-Var or 2-Var Stats analysis first to store a value to the sx variable. Then, follow the steps below:
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Calculate the population variance:
Press the "VARS" button located on the calculator.
Scroll down to the "Statistics" submenu and select option "5: variance(" by pressing the corresponding number and then "ENTER".
Press the "X²" key followed by the "ENTER" key to execute the population variance calculation.
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View the population variance:
The calculated population variance (sx²) will be displayed on the calculator screen.
For example, let's calculate the variance for the dataset {12, 15, 18, 20, 24}:
- Press [STAT] followed by [ENTER]
- Enter 12 and press [ENTER]
- Repeat the above step for the remaining data points.
- Press [2nd] followed by [QUIT]
- Press [STAT], scroll to the right, and press [1] or [ENTER]
- Press [ENTER]
- Ensure that List: is set to L1
- Scroll down to Calculate and press [ENTER]
- Press [VARS], scroll down to option 5, and press [ENTER]
- Press [4] or scroll down to option 4 and press [ENTER]
- Press [X²] followed by [ENTER]
- View the calculated sample variance on the calculator screen.
Note: The variance( command will find the sample variance, which is the sample standard deviation of x raised to the power of 2.
For more information and additional calculations, please refer to the TI-84 Plus Family guidebooks provided with the calculator. Check out z-table.com for more stats and math resources.