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Unit 13: Multivariate Analysis




          Further, we have                                                                      Notes
                           å U             å U                 å U
                      X  =    1  +  65 =  65,X =  2  +  55 =  55 and X =  3  +  30 =  30
                        1               2                   3
                             n               n                  n

               !
             Caution  The above method should be used when mean of all the variables are integers.

          Alternative Method
          The coefficients of the regression equation  X  = a   + b  X  + b  X  can also be obtained by
                                               1c  1.23  12.3  2  13.2  3
          simultaneously solving the following normal equations:
                                   SX  = na   + b  SX  + b  SX
                                     1    1.23  12.3  2  13.2  3
                                                      2
                                 SX X  = a  SX  + b  SX  + b  SX X
                                   1  2  1.23  2  12.3  2  13.2  2  3
                                 SX X  = a  SX  + b  SX X  + b  SX  2
                                   1  3  1.23  3  12.3  2  3  13.2  3
          Self Assessment

          Fill in the blanks:
          1.   Regression coefficient is independent of change of .......................

          2.   In the case of ………………regression, one variable is affected by a linear combination of
               another variable.
          3.   ……………..analysis is based on the statistical principle of multivariate statistics, which
               involves observation and analysis of more than one statistical variable at a time.

          13.2 Discriminant Analysis

          In this analysis, two or more groups are compared. In the final analysis, we need to find out
          whether the groups differ one from another.


               Example: Where discriminant analysis is used
          1.   Those who buy our brand and those who buy competitors’ brand.
          2.   Good salesman, poor salesman, medium salesman
          3.   Those who go to Food World to buy and those who buy in a Kirana shop.
          4.   Heavy user, medium user and light user of the product.
          Suppose there is a comparison between the groups mentioned as above along with demographic
          and socio-economic factors, then discriminant analysis can be used. One way of doing this is to
          proceed and calculate the income, age, educational level, so that the profile of each group could
          be determined. Comparing the two groups based on one variable alone would be informative
          but it would not indicate the relative importance of each variable in distinguishing the groups.
          This is because several variables within the group will have some correlation which means that
          one variable is not independent of the other.
          If we  are interested in segmenting  the market using income  and education,  we would  be
          interested in the total effect of two variables in combinations, and not their effects separately.
          Further, we would be interested in determining which of the variables are more important or





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