- #1
ducmod
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Homework Statement
Hello!
Here is the quote of mathisfun explanation of correlation formula and after ## my understanding or questions:
Let us call the two sets of data "x" and "y" (in our case Temperature is x and Ice Cream Sales is y):
Step 1: Find the mean of x, and the mean of y
Step 2: Subtract the mean of x from every x value (call them "a"), do the same for y (call them "b")
## with step 2 we compute how each variable differs from the mean
Step 3: Calculate: a × b, a2 and b2 for every value
## here I come to the point where I need help: I understand that we have to square each value from step 2 (a and b)
to avoid negative numbers;
## but I don't understand the meaning (ligic; why) of multiplication of variables from step 2 a x b
Step 4: Sum up a × b, sum up a2 and sum up b2
Step 5: Divide the sum of a × b by the square root of [(sum of a2) × (sum of b2)]
## in step 5 again I don't understand the logic of multiplication, what does this multiplication mean; and then the division.
## usually, division shows how many parts of divisor are in divident, or percent.
Thank you!