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Principles of Relationship

Dr. Anshul Singh Thapa

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Principles of Relationship

  • linear relationship between two variables
  • Range of the correlation coefficient is −1 to 1
  • There should be a logical concept between two variables
  • The data must be equal on both the variables
  • Subjects should be same

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linear relationship between two variables

  • The correlation coefficient is a measure of the strength and the direction of a linear relationship between two variables. The symbol r represents the sample correlation coefficient.

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Linear Correlation

x

y

Strong negative correlation

x

y

Weak positive correlation

x

y

Strong positive correlation

x

y

Nonlinear Correlation

r = −0.91

r = 0.88

r = 0.42

r = 0.07

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Range of the correlation coefficient is −1 to 1

  • The range of the correlation coefficient is −1 to 1. If x and y have a strong positive linear correlation, r is close to 1. If x and y have a strong negative linear correlation, r is close to −1. If there is no linear correlation or a weak linear correlation, r is close to 0.

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There should be a logical concept between two variables

  • The relationship between the variables can be seen when there is some theoretical aspect available in their support. For example the notion that height and good performance in basketball are associated with each other. Whereas color of the skin and playing ability of chess has no theoretical support, therefore no logical concept lie between the two variables.

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The data must be equal on both the variables

  • Since the correlation technique evaluate the association between the two variables. It is possible when the position of a score of one variable is seen in respect to the position of score of same individual on other variable. If the data is more in one variable and less in other it will not find accurate relationship between the two variables.

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Subjects should be same

  • The correlation identifies the association between the two variables, therefore the two different abilities (variables) of same sample is taken and relationship of two different abilities are calculated.
  • Two different groups cannot be correlated on some variables.