The relationship between statistical significance and effect size in the sphere of forensic psychology is extremely important because results can be discussed as psychologically significant and applied to a wide range of population only when the effect size is high (Little, 2013, p. 9). Thus, if the statistical significance is important to make conclusions regarding the overall effectiveness of the hypothesis in terms of the certain population, the effect size demonstrates the size of the expected effect or the closeness of the found results to the hypothesis in order to speak about its true or false character (Gravetter & Forzano, 2011, p. 465). From this point, the results are statistically and psychologically significant only when the effect size is high. In order to examine the relationship between effect size played and statistical significance in detail, it is necessary to refer to the analysis of two research articles in the field of forensic psychology.
In their research of 2005, Nee and Farman evaluated the effectiveness of using the dialectical behavior therapy for treating the borderline personality disorder in the UK female prisons. Psychometric tests, the analysis of behavioral data, and the analysis of interviews demonstrated the statistically significant changes in the state and behaviors of female prisoners (Nee & Farman, 2005, p. 8). However, to speak about the significance of the interventions to decease the criminogenic risk associated with the borderline personality disorder in females, it is important to refer to the noted effect size. Nee and Farman reported high effect sizes that ranged from.40 to.61 (Nee & Farman, 2005, p. 11). Focusing on these effect sizes, it is possible to concentrate on the significance of the results to expect improvements associated with using the proposed dialectical behavior therapy as treatment for the borderline personality disorder in imprisoned females.
The other reviewed article presents the results of the other research conducted by Nee and Farman in 2007. The researchers focused on studying how the dialectical behavior therapy can have the significant positive impact on the state of imprisoned females suffering from the borderline personality disorder. The authors’ conclusions based on the analysis of changes in the females’ behaviors and on the psychometric data (Nee & Farman, 2007, p. 162). It was found that the new results supported the statistically significant findings associated with the study of 2005. Much attention was paid to notable effect sizes in order to state whether the further development and use of the dialectical behavior therapy can have the positive results in the female prisons in the United Kingdom (Nee & Farman, 2007, p. 163). The focus on effect sizes is important when researchers work with small samples or individual’s cases in order to state whether the received results represent the statistically and psychologically significant changes.
The discussion of the effect size is important in order to determine the statistical significance of any study results. In order to speak about the effectiveness of the proposed treatments for the borderline personality disorder, it is necessary to refer to the results that not only support the hypothesis but also demonstrate significant positive changes reflected in effect sizes. From this point, when psychometric measures are used to examine differences, it is necessary to refer to the effect size in order to receive the accurate and credible information on possible improvements.
References
Gravetter, F., & Forzano, L. (2011). Research methods for the behavioral sciences. New York, NY: Cengage Learning.
Little, T. (2013). The Oxford handbook of quantitative methods in psychology. New York, NY: Oxford University Press.
Nee, C., & Farman, S. (2005). Female prisoners with borderline personality disorder: Some promising treatment developments. Criminal Behaviour and Mental Health, 15(2), 2-16.
Nee, C., & Farman, S. (2007). Dialectical behaviour therapy as a treatment for borderline personality disorder in prisons: Three illustrative case studies. The Journal of Forensic Psychiatry & Psychology, 18(2), 160-180.