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Example In a partially destroyed laboratory record of an analysis of correlation data, the following results are legible:

Variance of x = 9
Regression equations : 8 x - 10 y + 66 = 6

    40 x - 18 y = 214

What are (1) Means of x’s and y’s (2) the coefficient of correlation between x and y (3) the standard deviation of y ?

Solution:

  1. Means:

    8 x - 10 y = -66 ----- (1)

    40 x - 18 y = 214 ----- (2)

    Solving (1) and (2) as

    40 x - 50 y = -330 ----- (1)

    40 x - 18 y = 214 ----- (2)

    -32 y = -544

    y = 17

    \ Mean of y’s 17

    Substituting y = 17 in (1) we get 8x - 10 ´ 17 = -66

    or 8x = 104 \ x = 13

    \ Mean of x’s = 13


  2. Coefficient of correlation between x and y

    40 x = 18 y + 214

        

    Also -10 y = - 8 x - 66

Index

6. 1 Introduction
6. 2 Correlation
6. 3 Types of Correlation
6. 4 Degrees of Correlation
6. 5 Methods of determining correlation
6. 6 Coefficients of Correlation for Bivariate Grouped Data
6. 7 Probable Error
6. 8 Rank Correlation Coefficient
6. 9 Linear Regression

Chapter 7





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