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The aim of this investigation was to look at the reliability and validity of Hans Eysenck's EPI Test. The EPI questionnaire comprises of items of a 'yes/no' variety.

Extracts from this document...

Introduction

Abstract

The aim of this investigation was to look at the reliability and validity of Hans Eysenck’s EPI Test. The EPI questionnaire comprises of items of a ‘yes/no’ variety. They are essentially intended as research tools (as opposed to diagnostic tools for use in clinical settings) and, as such, ‘they are regarded as acceptable, reliable and valid’ (Kline 1981, Shackleton and Fletcher, 1984).The Alternative Hypothesis was that there would be a positive correlation between the E and N scores for forms A and B of the EPI. The Null Hypothesis was that there would not be a positive correlation between the scores for forms A and B, and any such found relationship would be down to chance factors operating.

The correlation study was carried out because we were looking for a relationship between the E scores and the N scores for forms A and B of Hans Eysenck’s EPI Test. The independent variable and dependent variable were not operationalised in this case because an experimental method was not being used and this investigation used test re-test reliability. A repeated measure design was used because it was quick, economical and cancelled out individual differences. Eighteen naïve psychology students, male and female were used for this investigation.  An opportunitive sample was used because it was quick, easy and could be carried out in a classroom.

The results, taken from the Raw Score Data table and scatter graph showed evidence of a positive correlation. However, to accept that this result was significant, we subjected the data to further statistical analysis.

...read more.

Middle

-1.5

2.5

6

16

17

11

9.5

16.5

2

4

7

23

23

18

17

23

1

1

8

5

6

1

1

5.5

0

0

9

12

13

7

4

12.5

3

9

10

10

19

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12

14.5

-8

64

11

22

20

17

13.5

21

3.5

12.25

12

19

17

14

9.5

18

3.5

12.25

13

14

18

9

11

16

-2

4

14

11

14

5.5

5.5

12.5

0

0

15

13

15

8

7

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15.5

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20.5

-1

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Σ d ² = 126

rs =      1-    6Σ d ²

                      n(n² - 1)

         =      1-     6 x 126      

                          18 (18² - 1)

         =      1-     6 x 126

                          18 (324 -1)

         =      1-     6 x 126

                         18 x 323

         =       1-     756

                          5814

         =       1-    0.130031

         = 0.869969

The Spearman’s coefficient of rank correlation for the relationship between the ‘E’ scores of form A and B is 0.87 (2dp). This is a strong positive correlation.  

image01.png

A result table illustrating the outcome of Eysenck’s personality inventory, illustrating the ‘E’ scores for form A and B.

...read more.

Conclusion

Limitations of design

The main limitations of the method in this investigation are that a correlation study establishes a relationship, but not a cause and effect relationship. The only way to be certain about this result would have been to devise an experiment to test the reliability of the EPI. However, the investigators failed to achieve this at the design stage.

Design Problems

The design used was a repeated measure and problems with this could include order effects such as learning, fatigue or boredom and subjects given the same test may do better due to practice. Also demand characteristics may become a problem; as the subject completes both conditions of the research, they may guess the aim of the investigation and act differently.

Conclusion

It has already been stated that this investigation was a one tailed test, with the number of people being eighteen. The calculated value for the ‘E’ score was 0.87. In order to be significant it had to exceed the critical table value, and in this case it did, at 0.01 level. Therefore we accepted the Alternative Hypothesis that there would be a positive correlation between the ‘E’ scores for forms A and B, and we rejected the Null .

We also used this comparison for the ‘N’ score. With the number of people being eighteen. The calculated value for the ‘N’ score was 0.90. In order to be significant it had to exceed the critical table value, and in this case it did, at 0.01 level. Therefore we accepted the Alternative Hypothesis that there would be a positive correlation between the ‘N’ scores for forms A and B, and we rejected the Null .

...read more.

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