How to Calculate Covariance From a TI-84

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A TI-84 calculator makes computing covariance possible.

If you have recently acquired a TI-84 graphing calculator from Texas Instruments, then you may be wondering how to use the calculator to determine complex mathematical equations. For example, you can calculate covariance on a TI-84, which is the measurement of a linear relationship. Learn the basics of inputting data into your TI-84, which functions much like a miniature computer. Memorize the formula for calculating covariance for quick computations.

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Step 1

Turn on your TI-84 by pressing the "On" button.

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Step 2

Calculate the mean of each of your variables X and Y. The mean is the average of a set of numbers.

For example, for this exercise X's data set is (1, 2, 3,4) and Y's data set is (5,6,7,8). Type the following formula and press "Enter" to find the average of X: (1 + 2 + 3 + 4)/4. The average of X is 2.5. Type the following formula and press "Enter" to find the average of Y: (5 + 6 + 7 + 8)/4. The average of Y is 6.5.

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Step 3

Multiply corresponding data from each set X and Y.

For example, here are your two sets of data:

X : 1,2,3,4 Y : 5,6,7,8

Type into your calculator each of these equations, followed by "Enter" :

1 X 5 2 X 6 3 X 7 4 X 8

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Your answers will be the following: 5, 12, 21, 32

Step 4

Calculate the mean of this set of data: 5, 12, 21, 32

Type (5 +12 + 21 + 32)/4 and "Enter."

You will get 17.5.

Step 5

Multiply the means of X and Y.

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Type 2.5 X 6.5. Press "Enter."

Your answer is 16.5.

Step 6

Subtract 17.5 - 16.5. Press "Enter."

Your covariance is 1.

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