Hi:
As a service to the community, my university has sponsored a podcast in
which I talk about the problems of endogeneity.
These podcasts, which are freely available on Youtube, are primarily
methodological; however, they have very important implications for the
development of theoretical models in OB, leadership, and related areas.
I show with simple and salient examples how endogeneity is engendered by
omitted varianbles, common-method variance, and the like. I discuss how
to deal with endogeneity by using "instrumental variables," and also
show that endogeneity can also be present when testing mediation (which
means that experiments can also be threatened by endogeneity too).
There are three versions of the podcast:
1. Endogeneity: An inconvenient truth (full version)
(about 32 minutes in length)
http://www.youtube.com/watch?v=dLuTjoYmfXs
Description:
A key assumption of regression analysis (or structural equation
modeling) is that the modeled independent variables are not endogenous.
Yet, the problems of endogeneity are not well known to researchers
working in many social sciences disciplines (e.g., management, applied
psychology, sociology, etc.). When the independent variable has not been
exogenously manipulated, there is a strong possibility that its
relationship to a dependent variable will not be correctly estimated,
leading to spurious findings. This podcast gives a brief and vivid
overview to endogeneity and why it is engendered. Prof. John Antonakis
discusses the problems of endogeneity using non-technical language and
intuitive explanations; he shows that when the independent variable is
endogenous--which is also possible in experimental designs (when the
mediator is endogenous)--the observed relationship that is estimated can
be very misleading. Prof. Antonakis demonstrates how the problem of
endogeneity can be solved using procedures borrowed from econometrics
(i.e., two-stage least square regression estimator).
2. Endogeneity: An inconvenient truth (a gentle introduction)
(this is really a gentle introduction on omitted variable bias; does not
discuss two-stage least squares and mediation; about 19 minutes in length)
http://www.youtube.com/watch?v=CCiIfjm8qjw
Description:
A key assumption of regression analysis (or structural equation
modeling) is that the modeled independent variables are not endogenous.
Yet, the problems of endogeneity are not well known to researchers
working in many social sciences disciplines (e.g., management, applied
psychology, sociology, etc.). When the independent variable has not been
exogenously manipulated, there is a strong possibility that its
relationship to a dependent variable will not be correctly estimated,
leading to spurious findings. This podcast gives a brief and vivid
overview to endogeneity and why it is engendered. Prof. John Antonakis
discusses the problems of endogeneity using non-technical language and
intuitive explanations; he shows that the observed relationship that is
estimated can be very misleading when the independent variable is
endogenous.
3. Endogeneity: An inconvenient truth (for researchers)
(Excludes the "gentle introduction" content and discusses the two-stage
least squares estimator straight away; about 16 minutes in length)
http://www.youtube.com/watch?v=yi_5M7oUceE
Description:
It is well known that endogeneity leads to inconsistent estimates.
Unfortunately, many researchers working outside of economics are not
aware of the problem of endogeneity and how to deal with it. Prof. John
Antonakis shows how the two-stage least squares (2SLS) estimator
recovers causal estimates in the presence of endogeneity (which includes
the problem of common-method variance). He also shows that endogeneity
can even be prevalent in experimental designs, when researchers estimate
mediation models; that is, where the causal effect of an exogenous
variable on a dependent variable is mediated by an endogenous variable
(or a manipulation check).
The podcasts are an accompaniment to the following papers (which are
written in very general terms and useful for many disciplines):
Antonakis, J., Bendahan, S., Jacquart, P., & Lalive, R. (2010). On
making causal claims: A review and recommendations. The Leadership
Quarterly, 21(6). 1086-1120.
Antonakis, J., Bendahan, S., Jacquart, P., & Lalive, R. (submitted).
Causality and endogeneity in leadership research: Problems and
solutions. In D.V. Day (Ed.), The Oxford Handbook of Leadership and
Organizations.
If interested, please contact me for copies.
The I trust that you find the podcasts useful, particularly for teaching
purposes.
All the best,
John.
--
__________________________________________
Prof. John Antonakis
Faculty of Business and Economics
Department of Organizational Behavior
University of Lausanne
Internef #618
CH-1015 Lausanne-Dorigny
Switzerland
Tel ++41 (0)21 692-3438
Fax ++41 (0)21 692-3305
http://www.hec.unil.ch/people/jantonakis
Associate Editor
The Leadership Quarterly