Correlation indicates the strength and direction of a linear relationship between two variables and can range from -1 to 1, where -1 is a perfect negative correlation, 1 is a perfect positive correlation, and 0 is no correlation. A correlation of 1 means the variables increase together, a correlation of -1 means one variable increases as the other decreases, and r is calculated by taking the covariance of the two variables divided by the product of their standard deviations. While correlation may be found, it does not necessarily imply that one variable causes the other.

1. Correlation I
SHO SHIMODA
2015/02/10

2. Overview
Correlation indicated patterns of which two
sets data may have similar patterns.

3. 1 or -1
Correlation can be 1 when two sets of data
have perfectly positive incremental
relationship, and -1 if two sets of data have
perfectly negative incremental (or call it
decrease) relationship.

4. Use
Finding correlation is used for linear. The
equation does not work for curves.

5. Relationship
You may find correlation but two sets of data
does not necessary cause others to
correlate.

6. r
Where r is the correlation value;

7. r
1. Find mean of set values x and y, and
subtract the mean from each values.
2. Sum up each
a. x multiple by y
b. Square of x and y
3. Then the value of a. divide by square root
of x square multiple of y square.

8. r
Try with real data sets.

9. SHO SHIMDOA
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