Step - by - Step Analysis of SPSS Correlation Procedure by vasana

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                       ANALYZING DATA IN SPSS 13.0 USING CORRELATION


Tips before you begin:
•   Make sure your data set is open before attempting to run any analyses.
•   During analyses, right click on terms or buttons in the dialog boxes to learn about their functions.
•   The Help button in the dialog boxes maybe clicked at any time during analyses for more
    information on that particular procedure.
•   Click the Reset button to clear the dialog box and begin a fresh analysis.
•   Click the Cancel button to exit that dialog box without saving changes.


Choose a Procedure:
•   Bivariate Correlations
•   Partial Correlations
•   Distances


BIVARIATE CORRELATIONS
In Bivariate Correlations, the relationship between two variables is measured. The degree of
relationship (how closely they are related) could be either positive or negative. The maximum number
could be either +1 (positive) or -1 (negative). This number is the correlation coefficient. A zero
correlation indicates no relationship.


Examples. Are a student’s grade and the amount of studying done correlated? You might find that
these variables are positively correlated. Or say, is the number of games won by a basketball team
correlated with the average number of points scored per game?


Procedure
1. On the menu bar of the SPSS Data Editor window, click Analyze > Correlate > Bivariate…




2. Select one or more variables that you want to analyze by clicking on the variable labels in the
    Bivariate Correlations dialog box. To select multiple variables, hold down the Ctrl key and choose


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     the variables you want. Click on the arrow button to add selected variables to the Variables
     window.




 List of                                                                                                  Empty
Variables                                                                                                Variables
                                                                                                          Window




                                                                                                         Right arrow
                                                                                                        button to add
                                                                                                          selected
                                                                                                         variable(s)




 3. Check the type of correlation coefficients that you require (Pearson for parametric, and Kendall’s
     tau-b and Spearman for non-parametric).


 4. Click on the Options… button to
     select statistics, and to control the
     treatment of missing values. Click
     on the Continue button.




 5. Click the OK button in the Bivariate Correlations dialog box to run the analysis. The output will be
     displayed in a separate SPSS Viewer window.
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 PARTIAL CORRELATIONS
 The Partial Correlations procedure computes partial correlation coefficients that describe the linear
 relationship between two variables while controlling for the effects of one or more additional variables.
 Correlations are measures of linear association. Two variables can be perfectly related, but if the
 relationship is not linear, a correlation coefficient is not a proper statistic to measure their association.

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     Example. Is there a relationship between healthcare funding and disease rates? Although you might
     expect any such relationship to be a negative one, a study reports a significant positive correlation: as
     healthcare funding increases, disease rates appear to increase. Controlling for the rate of visits to
     healthcare providers, however, virtually eliminates the observed positive correlation. Healthcare
     funding and disease rates only appear to be positively related because more people have access to
     healthcare when funding increases, which leads to more reported diseases by doctors and hospitals.


     Procedure
     1. On the menu bar of the SPSS Data Editor window, click Analyze > Correlate > Partial…




     2. Select one or more variables that you want to analyze by clicking on the variable labels in the
         Partial Correlations dialog box. Also select one or more numeric control variables. To select
         multiple variables, hold down the Ctrl key and choose the variables you want. Click on the
         respective arrow buttons to add selected variables to the Variables and Controlling for windows.




                                                                                                              Empty
   List of                                                                                                   Variables
  Variables                                                                                                   Window



                                                                                                             Empty
                                                                                                          Controlling
                                                                                                          for Window
 Right arrow
 buttons to
add selected
 variable(s)




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3. Click on the Options… button to
    select statistics, and to control the
    treatment of missing values. Click
    on the Continue button.




4. Click the OK button in the Partial Correlations dialog box to run the analysis. The output will be
    displayed in a separate SPSS Viewer window.
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DISTANCES
This procedure calculates any of a wide variety of statistics measuring either similarities or
dissimilarities (distances), either between pairs of variables or between pairs of cases. These similarity
or distance measures can then be used with other procedures, such as factor analysis, cluster
analysis, or multidimensional scaling, to help analyze complex data sets.


Example: Is it possible to measure similarities between pairs of automobiles based on certain
characteristics, such as engine size, MPG, and horsepower? By computing similarities between autos,
you can gain a sense of which autos are similar to each other and which are different from each other.


Procedure
1. On the menu bar of the SPSS Data Editor window, click Analyze > Correlate > Distances…




2. Select one or more variables that you want to analyze by clicking on the variable labels in the
    Distances dialog box. Optionally, select a single string variable for the Label Cases by window. To
    select multiple variables, hold down the Ctrl key and choose the variables you want. Click on the
    respective arrow buttons to add selected variables to the Variables and Label Cases by windows.


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                                                                                                               Empty
  List of                                                                                                     Variables
 Variables                                                                                                     Window




                                                                                                                Empty
                                                                                                             Label Cases
                                                                                                              by Window
 Right arrow
 buttons to
add selected
 variable(s)




        3. Select the type of distance to compute and the type of measure that you require.


        4. Click on the
               Measures… button to
               explicitly define options
               for dissimilarity or
               similarity measures.
               Click on the Continue
               button.




        5. Click the OK button in the Distances dialog box to run the analysis. The output will be displayed in
               a separate SPSS Viewer window.
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