Extensions of Tests of Indirect Effect in Mediation Analysis

Chike Henry Nwankwo; Amechi Henry Igweze

doi:doi:10.11648/j.ijdsa.20160201.11

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Extensions of Tests of Indirect Effect in Mediation Analysis

Chike Henry Nwankwo, Amechi Henry Igweze

Published in International Journal of Data Science and Analysis (Volume 2, Issue 1)

Received: 19 July 2016 Accepted: 27 July 2016 Published: 5 September 2016

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Abstract

This study seeks to determine economic variables that jointly mediate upon government expenditure and unemployment in Nigeria and in proven cases of mediation, determine the type of mediation that exist. It compares the two methods of calculating indirect effect which are product of coefficient and difference of coefficients respectively. Furthermore, the study compares the three methods of testing the significance of indirect effect vis-à-vis Sobel’s test, Aroian test and Goodman’s test. The differences in these three tests are due to variations in the methods of standard error computation. This study further proposed extensions for the three variations in methods of standard error computation for a case of two mediator which may also be extended for more than two mediator cases. The results show that a combination of any two of labour force population, interest rate and inflation showed a significant evidence of partial mediation. The result of indirect effect computation shows that the method of product of coefficient gave a slightly higher result when compared to that of difference of coefficient. The proposed extension of Sobel, Aroian and Goodman tests gave the same result for all cases as their standard errors are the same. The study thus recommends employing some variable selection techniques in subsequent studies which may improve mediational results; further studies may to be carried out to seek methods of ascertaining the direction of relationship of indirect effect, other than those of the regression models; and finally studies may be carried out to determine the effect of multicolinearity on mediation results.

Published in	International Journal of Data Science and Analysis (Volume 2, Issue 1)
DOI	10.11648/j.ijdsa.20160201.11
Page(s)	1-6
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2016. Published by Science Publishing Group

Keywords

Aroian Test, Sobel Test, Goodman Test, Indirect Effect, Mediation

References

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[2]	Congress Of The United States Congressional Budget Office, CBO (2012) Understanding and Responding to Persistently High Unemployment.
[3]	Doğan, T. T (2012). Macroeconomic Variables and Unemployment: The Case of Turkey. International Journal of Economics and Financial Issues Vol. 2 (1).
[4]	El-Agrody, N. M., Othman, A. Z., & Hassan, M. B.-D. (2010). Economic Study of Unemployment in Egypt and Impacts on GDP. Nature and Science, 8 (10), 102-111.
[5]	Imai, K.; Keele, L. & Tingley, D. (2010). A General Approach to Causal Mediation Analysis.' Psychological Methods, Vol. 15, No. 4 (December), pp. 309-334. International statistics p.
[6]	Judd CM, Kenny DA. (1981) Process analysis: Estimating mediation in treatment evaluations. Evaluation. Review. (5) pp: 602–619.
[7]	Lui, L. Q. (2009). Inflation and Unemployment: The roles of goos and labor market institution. 1 31.
[8]	Milovanović, B (2013) About Hidden Influence Of Predictor Variables-Suppressor And Mediator Variables. J. Geogr. Inst. Cvijic. 63 (2) (1-10).
[9]	Oyeka, I. C. A., Nwankwo, C H (2014). Direct and Indirect Effects in Dummy Variable Regression. American Journal of Theoretical and Applied Statistics. Vol. 3, No. 2, 2014, pp. 44-48. doi: 10.11648/j.ajtas.20140302.
[10]	Pallis, D. (2006). The tradeoff between inflation and unemployment in new European Union member-states. International Research Journal of Finance and Economics (1), 81-97.
[11]	Preacher, K. J., & Hayes, A. F. (2008). Contemporary approaches to assessing mediation in communication research. In A. F. Hayes, M. D.
[12]	Sobel, M. E. (1982). Asymptotic Confidence Intervals for Indirect Effects in Structural equations models. In S. Leinhart (Ed.), Sociological methodology 1982 (pp. 290-312). San Francisco: Jossey-Bass.
[13]	Sobel, M. E. (1986). Some new results on indirect effects and their standard errors in covariance structure models. In N. Tuma (Ed.), Sociological Methodology 1986 (pp. 159-186). Washington, DC: American Sociological Association.
[14]	Suradi, N. R. M, Ali, Z. M; Alwi, H. Z. M; Norafidah, S and Ramli, M (2009) Testing For Mediating Variable In A Regression Model. International Conference on Quality, Productivity and Performance Measurement.
[15]	Tunah, H. (2010). The Analysis of Unemployment in Turkey: Some Empirical Evidence Using Co integration Test. European Journal of Social Sciences, 18 (1), 18-38.

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Chike Henry Nwankwo, Amechi Henry Igweze. (2016). Extensions of Tests of Indirect Effect in Mediation Analysis. International Journal of Data Science and Analysis, 2(1), 1-6. https://doi.org/10.11648/j.ijdsa.20160201.11

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ACS Style

Chike Henry Nwankwo; Amechi Henry Igweze. Extensions of Tests of Indirect Effect in Mediation Analysis. Int. J. Data Sci. Anal. 2016, 2(1), 1-6. doi: 10.11648/j.ijdsa.20160201.11

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AMA Style

Chike Henry Nwankwo, Amechi Henry Igweze. Extensions of Tests of Indirect Effect in Mediation Analysis. Int J Data Sci Anal. 2016;2(1):1-6. doi: 10.11648/j.ijdsa.20160201.11

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@article{10.11648/j.ijdsa.20160201.11,
  author = {Chike Henry Nwankwo and Amechi Henry Igweze},
  title = {Extensions of Tests of Indirect Effect in Mediation Analysis},
  journal = {International Journal of Data Science and Analysis},
  volume = {2},
  number = {1},
  pages = {1-6},
  doi = {10.11648/j.ijdsa.20160201.11},
  url = {https://doi.org/10.11648/j.ijdsa.20160201.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijdsa.20160201.11},
  abstract = {This study seeks to determine economic variables that jointly mediate upon government expenditure and unemployment in Nigeria and in proven cases of mediation, determine the type of mediation that exist. It compares the two methods of calculating indirect effect which are product of coefficient and difference of coefficients respectively. Furthermore, the study compares the three methods of testing the significance of indirect effect vis-à-vis Sobel’s test, Aroian test and Goodman’s test. The differences in these three tests are due to variations in the methods of standard error computation. This study further proposed extensions for the three variations in methods of standard error computation for a case of two mediator which may also be extended for more than two mediator cases. The results show that a combination of any two of labour force population, interest rate and inflation showed a significant evidence of partial mediation. The result of indirect effect computation shows that the method of product of coefficient gave a slightly higher result when compared to that of difference of coefficient. The proposed extension of Sobel, Aroian and Goodman tests gave the same result for all cases as their standard errors are the same. The study thus recommends employing some variable selection techniques in subsequent studies which may improve mediational results; further studies may to be carried out to seek methods of ascertaining the direction of relationship of indirect effect, other than those of the regression models; and finally studies may be carried out to determine the effect of multicolinearity on mediation results.},
 year = {2016}
}

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TY  - JOUR
T1  - Extensions of Tests of Indirect Effect in Mediation Analysis
AU  - Chike Henry Nwankwo
AU  - Amechi Henry Igweze
Y1  - 2016/09/05
PY  - 2016
N1  - https://doi.org/10.11648/j.ijdsa.20160201.11
DO  - 10.11648/j.ijdsa.20160201.11
T2  - International Journal of Data Science and Analysis
JF  - International Journal of Data Science and Analysis
JO  - International Journal of Data Science and Analysis
SP  - 1
EP  - 6
PB  - Science Publishing Group
SN  - 2575-1891
UR  - https://doi.org/10.11648/j.ijdsa.20160201.11
AB  - This study seeks to determine economic variables that jointly mediate upon government expenditure and unemployment in Nigeria and in proven cases of mediation, determine the type of mediation that exist. It compares the two methods of calculating indirect effect which are product of coefficient and difference of coefficients respectively. Furthermore, the study compares the three methods of testing the significance of indirect effect vis-à-vis Sobel’s test, Aroian test and Goodman’s test. The differences in these three tests are due to variations in the methods of standard error computation. This study further proposed extensions for the three variations in methods of standard error computation for a case of two mediator which may also be extended for more than two mediator cases. The results show that a combination of any two of labour force population, interest rate and inflation showed a significant evidence of partial mediation. The result of indirect effect computation shows that the method of product of coefficient gave a slightly higher result when compared to that of difference of coefficient. The proposed extension of Sobel, Aroian and Goodman tests gave the same result for all cases as their standard errors are the same. The study thus recommends employing some variable selection techniques in subsequent studies which may improve mediational results; further studies may to be carried out to seek methods of ascertaining the direction of relationship of indirect effect, other than those of the regression models; and finally studies may be carried out to determine the effect of multicolinearity on mediation results.
VL  - 2
IS  - 1
ER  -

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Author Information

Chike Henry Nwankwo

Department of Statistics, Nnamdi Azikiwe University, Awka, Nigeria
Amechi Henry Igweze

Department of Mathematics and Statistics, Delta State Polytechnic, Ogwashi-Uku, Nigeria

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Plain Text BibTeX RIS

APA Style

Chike Henry Nwankwo, Amechi Henry Igweze. (2016). Extensions of Tests of Indirect Effect in Mediation Analysis. International Journal of Data Science and Analysis, 2(1), 1-6. https://doi.org/10.11648/j.ijdsa.20160201.11

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ACS Style

Chike Henry Nwankwo; Amechi Henry Igweze. Extensions of Tests of Indirect Effect in Mediation Analysis. Int. J. Data Sci. Anal. 2016, 2(1), 1-6. doi: 10.11648/j.ijdsa.20160201.11

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AMA Style

Chike Henry Nwankwo, Amechi Henry Igweze. Extensions of Tests of Indirect Effect in Mediation Analysis. Int J Data Sci Anal. 2016;2(1):1-6. doi: 10.11648/j.ijdsa.20160201.11

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@article{10.11648/j.ijdsa.20160201.11,
  author = {Chike Henry Nwankwo and Amechi Henry Igweze},
  title = {Extensions of Tests of Indirect Effect in Mediation Analysis},
  journal = {International Journal of Data Science and Analysis},
  volume = {2},
  number = {1},
  pages = {1-6},
  doi = {10.11648/j.ijdsa.20160201.11},
  url = {https://doi.org/10.11648/j.ijdsa.20160201.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijdsa.20160201.11},
  abstract = {This study seeks to determine economic variables that jointly mediate upon government expenditure and unemployment in Nigeria and in proven cases of mediation, determine the type of mediation that exist. It compares the two methods of calculating indirect effect which are product of coefficient and difference of coefficients respectively. Furthermore, the study compares the three methods of testing the significance of indirect effect vis-à-vis Sobel’s test, Aroian test and Goodman’s test. The differences in these three tests are due to variations in the methods of standard error computation. This study further proposed extensions for the three variations in methods of standard error computation for a case of two mediator which may also be extended for more than two mediator cases. The results show that a combination of any two of labour force population, interest rate and inflation showed a significant evidence of partial mediation. The result of indirect effect computation shows that the method of product of coefficient gave a slightly higher result when compared to that of difference of coefficient. The proposed extension of Sobel, Aroian and Goodman tests gave the same result for all cases as their standard errors are the same. The study thus recommends employing some variable selection techniques in subsequent studies which may improve mediational results; further studies may to be carried out to seek methods of ascertaining the direction of relationship of indirect effect, other than those of the regression models; and finally studies may be carried out to determine the effect of multicolinearity on mediation results.},
 year = {2016}
}

Copy | Download

TY  - JOUR
T1  - Extensions of Tests of Indirect Effect in Mediation Analysis
AU  - Chike Henry Nwankwo
AU  - Amechi Henry Igweze
Y1  - 2016/09/05
PY  - 2016
N1  - https://doi.org/10.11648/j.ijdsa.20160201.11
DO  - 10.11648/j.ijdsa.20160201.11
T2  - International Journal of Data Science and Analysis
JF  - International Journal of Data Science and Analysis
JO  - International Journal of Data Science and Analysis
SP  - 1
EP  - 6
PB  - Science Publishing Group
SN  - 2575-1891
UR  - https://doi.org/10.11648/j.ijdsa.20160201.11
AB  - This study seeks to determine economic variables that jointly mediate upon government expenditure and unemployment in Nigeria and in proven cases of mediation, determine the type of mediation that exist. It compares the two methods of calculating indirect effect which are product of coefficient and difference of coefficients respectively. Furthermore, the study compares the three methods of testing the significance of indirect effect vis-à-vis Sobel’s test, Aroian test and Goodman’s test. The differences in these three tests are due to variations in the methods of standard error computation. This study further proposed extensions for the three variations in methods of standard error computation for a case of two mediator which may also be extended for more than two mediator cases. The results show that a combination of any two of labour force population, interest rate and inflation showed a significant evidence of partial mediation. The result of indirect effect computation shows that the method of product of coefficient gave a slightly higher result when compared to that of difference of coefficient. The proposed extension of Sobel, Aroian and Goodman tests gave the same result for all cases as their standard errors are the same. The study thus recommends employing some variable selection techniques in subsequent studies which may improve mediational results; further studies may to be carried out to seek methods of ascertaining the direction of relationship of indirect effect, other than those of the regression models; and finally studies may be carried out to determine the effect of multicolinearity on mediation results.
VL  - 2
IS  - 1
ER  -

Copy | Download