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Question
Define Correlation.
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Solution
Correlation is a statistical device that helps to analyze the covariation of two or more variables. Sir Francis Galton, is responsible for the calculation of the correlation coefficient.
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RELATED QUESTIONS
In the following data one of the value of y is missing. Arithmetic means of x and y series are 6 and 8 respectively. `(sqrt(2) = 1.4142)`
| x | 6 | 2 | 10 | 4 | 8 |
| y | 9 | 11 | ? | 8 | 7 |
Estimate missing observation.
Calculate the correlation coefficient for the following data.
| X | 5 | 10 | 5 | 11 | 12 | 4 | 3 | 2 | 7 | 1 |
| Y | 1 | 6 | 2 | 8 | 5 | 1 | 4 | 6 | 5 | 2 |
Calculate the coefficient of correlation between X and Y series from the following data.
| Description | X | Y |
| Number of pairs of observation | 15 | 15 |
| Arithmetic mean | 25 | 18 |
| Standard deviation | 3.01 | 3.03 |
| Sum of squares of deviation from the arithmetic mean | 136 | 138 |
Summation of product deviations of X and Y series from their respective arithmetic means is 122.
Find the coefficient of correlation for the following:
| X | 78 | 89 | 96 | 69 | 59 | 79 | 68 | 62 |
| Y | 121 | 72 | 88 | 60 | 81 | 87 | 123 | 92 |
Example for positive correlation is
If the values of two variables move in the opposite direction then the correlation is said to be
Correlation co-efficient lies between
From the following data, N = 11, ∑X = 117, ∑Y = 260, ∑X2 = 1313, ∑Y2 = 6580, ∑XY = 2827 the correlation coefficient is
The correlation coefficient is
Scatter diagram of the variate values (X, Y) give the idea about
If two variables moves in decreasing direction then the correlation is
If r = – 1, then correlation between the variables
The coefficient of correlation describes
Calculate the correlation coefficient from the data given below:
| X | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| Y | 9 | 8 | 10 | 12 | 11 | 13 | 14 | 16 | 15 |
A measure of the strength of the linear relationship that exists between two variables is called:
If both variables X and Y increase or decrease simultaneously, then the coefficient of correlation will be:
If the points on the scatter diagram indicate that as one variable increases the other variable tends to decrease the value of r will be:
The value of the coefficient of correlation r lies between:
State and explain the different kinds of Correlation.
