What is Meta-Regression Analysis?
MRA is the statistical analysis of previously reported regression results
(Stanley and Jarrell, 1989). It seeks to summarize and explain the disparate
empirical findings routinely reported in nearly all areas of economics. Over
the last several decades,听a thousand听meta-analyses have been
conducted in economics, with over 100 new ones appearing each year.
What would an efficient market look like?听
Source: Kim,听et al.听(2014).
What have meta-analysts learned?
-
Publication
selection inflation is found in the majority of economic research areas,
and its effects are often larger than the magnitude of underlying economic
phenomenon being investigated (Doucouliagos and Stanley, 2014; Ioannidis
et al, 2017).
- Regression model
misspecification is, in fact, the principal cause for the observed
variation among reported economic findings, confirming the concerns
famously expressed by Leamer (1983), Summers (1991), Sala-i-Martin(1997),
and others.
- That environmental
values may be transferred from MRA to unstudied sites (Rosenberger and
Loomis, 2000; Johnston
and Rosenberger, 2010, Johnston et al., 2015)
- The empirical
literature often contains strong evidence against widely held economic
theory and contrary to conventional narrative reviews (Stanley, 2001;
Stanley, 2004; Stanley, 2005b; Doucouliagos and Stanley, 2009). Without
some objective and systematic method of literature reviewing, conventional
narrative reviews can draw any conclusions their authors wish.
- Economics research is
highly underpowered. A
of 64,076 economic estimates from 159 areas of research and 6,700
empirical studies finds that the median statistical power is 18%, or
less.听 Impotence begets bias. Typically,
reported economic effects are inflated by 100% with one-third inflated by
a factor of four or more.听
Introductions to meta-regression analysis can be found in Stanley and Jarrell (1989), Stanley (2001), Stanley (2013), Stanley and Doucouliagos (2012), and Doucouliagos (2016).
Publication Selection Inflation
"Many other commentators have addressed the issue of publication bias ... All agree that it is a serious problem" (Begg and Berlin, 1988, p.421)
"Are all economic hypotheses false?鈥 de Long and Lang (1992) rhetorically asked. Researchers, reviewers and editors treat 鈥榮tatistically significant鈥 results more favorably; hence, they are more likely to be published. Studies that find relatively small and 鈥榠nsignificant鈥 effects are much less likely to be published, because they may be thought to say little about the phenomenon in question. Publication selection bias is so strong that we are likely to be better off discarding 90% of the research results than to take them at face value (Stanley, Jarrell and Doucouliagos, 2010).
鈥(P)ublication bias is leading to a new formulation of Gresham鈥檚 law 鈥攍ike bad money, bad research drives out good鈥 (Bland,1988, p.450).
Funnel graphs should look like this one, below, for the union-productivity literature, though they seldom do.
听Many economists have turned their attention to the issue of publication selection and have used meta-regression analysis to identify and correct it.
- Card, D., Krueger,
A.B., 1995. Time-series minimum-wage studies: A meta-analysis. American
Economic Review 85, 238-43.
- Rose, A.K., Stanley,
T.D., 2005. A Meta-Analysis of the effect on common currency on
international trade, Journal of Economic Surveys 19, 347-65.
- Stanley, T.D., 2005.
Beyond publication bias, Journal of Economic Surveys 19, 309-45.
- Doucouliagos, H.,
Paldam, M., 2006. Aid effectiveness on accumulation: A meta study. Kyklos
59: 227-54.
- Disdier, AC and K
Head 2008. The puzzling persistence of the distance effect on bilateral trade.
Review of Economics and Statistics 90: 37-44.
- Doucouliagos, Hristos
and Stanley, T.D. 2009. Publication selection bias in minimum-wage
research? A meta-regression analysis,鈥 British Journal of Industrial
Relations, 47: 406-28.
- Havranek, T. 2016.
Measuring intertemporal substitution: The importance of method choices and
selective reporting, Journal of the European Economic Association,
13:1180-204.
- Doucouliagos, H.,
T.D. Stanley and M. Giles. (2012). Are estimates of the value of a statistical
life exaggerated? Journal of Health
Economics, 31: 197-206.
- Viscusi, W.K. 2015. The role of publication
bias in estimates of the value of a statistical life. American Journal
of Health Economics 1 (1): 27鈥52.
No other approach can cleanse the economic literature of the distorting effect of publication selection. Economists have begun to develop MRA methods that might 鈥榮olve鈥 this fundamental problem of empirical science and to render this bias mostly harmless.听
- Stanley, T.D.,
2005a. Beyond publication bias, Journal of Economic Surveys 19, 309-45.
- Stanley, T.D., 2008.
Meta-regression methods for detecting and estimating empirical effect in
the presence of publication selection, Oxford Bulletin of Economics and
Statistics 70, 103-127.
- Stanley, T.D. and
Chris Doucouliagos, 2012. Meta-Regression Analysis in Economics and
Business. Routledge.听
- Stanley, T.D. and
Chris Doucouliagos, 2014, Meta-regression approximations to reduce
publication selection bias, Research Synthesis Methods 5 (2014),
60-78.
- Stanley T. D. and Doucouliagos,
H. 2017. Neither fixed nor random: Weighted least squares meta-regression
analysis, Research Synthesis Methods
8, 19-42.听
- Stanley, T.D.,
Doucouliagos, C. and Ioannidis, J.P.A. 2017. Finding the power to reduce publication
bias. Statistics in Medicine,
36: 1580-1598.听
In an era characterized by the rapid expansion of research publications and a flood of empirical findings on any given subject, knowledge and sensible policy action are being drowned. All reviews, whether conventional or meta, are vulnerable to publication selection bias. Without some objective and balanced way to integrate this sea of results, ideology and self-serving deceit will dominate the public discussion of economic research. What we need is some objective and critical methodology to integrate diverse research findings and to reveal the nuggets of 鈥榯ruth鈥 that have settled to the bottom. This is precisely what Meta-Regression Analysis (MRA) can do!
References:
Begg, C. B., Berlin, J.A., 1988. Publication bias: A
problem in interpreting medical data, Journal of the Royal Statistical
Society (Series A) 151, 419-445.
Bland, J.M., 1988. Discussion of the paper by Begg and
Berlin, Journal of the Royal Statistical Society (Series A) 151,
450-451.
De Long, J.B. and Lang, K. 1992. Are all economic
hypotheses false? Journal of Political Economy 100:1257-72.
Doucouliagos, H. 2016. Meta-regression
analysis: Producing credible estimates from diverse evidence. IZA World of Labor 2016: 320 doi:
10.15185/izawol.320 .
Doucouliagos, C.(H) and Laroche, P. 2003.
What do unions do to productivity: A meta-analysis鈥, Industrial Relations, 42: 650-91.
Doucouliagos, H., T.D. Stanley and M. Giles. (2012). Are estimates
of the value of a statistical life exaggerated? Journal of Health Economics, 31: 197-206.
Doucouliagos, H. and Stanley, T.D. 2013. Theory
competition and selectivity: Are all economic facts greatly exaggerated? Journal
of Economic
Surveys, 27: 316-39.
Ioannidis, J.P.A., Stanley, T.D. and Doucouliagos, C.
(2017). , The
Economic Journal, 127: F236-265.
Havranek, T. 2016.
Measuring intertemporal substitution: The importance of method choices and
selective reporting, Journal of the European Economic Association,
13:1180-204.
Johnston, R.J. 听and R.S. Rosenberger, (2010). Methods, trends and controversies in contemporary benefit transfer. Journal of Economic Surveys 24(2010):479鈥510.
Johnston,
R.J., Rolfe, J., Rosenberger, R.S. and R. Brouwer (2015). Benefit Transfer
of Environmental and Resource Values: A Guide for Researchers and Practitioners.
The Netherlands: Springer.
Kim, J., Doucouliagos, H., and
Stanley, T.D., (2014). : A fresh look at the evidence,
Deakin University School of Business and Law, SWP 2014/9.
Krakovsky, M., 2004. Register or perish, Scientific
American 291(Dec.), 18-20.
Leamer, E. E. (1983) Let's take the con out of
econometrics. American Economic Review 73, 31-43.
Rosenberger, R.S., Loomis, J.B., 2000. Using
meta-analysis for benefit transfer: in-sample convergent validity tests of an
outdoor recreation database. Water Resources Research 36 (4), 1097鈥1107.
Sala-i-Martin, X., 1997. I just ran 2 million
regressions. American Economic Review 87, 178-183.
Stanley, T.D., 2001. Wheat from chaff: Meta-analysis as
quantitative literature review, Journal of Economic Perspectives, 15,
131-50.
Stanley, T.D., 2004. Does unemployment hysteresis falsify
the Natural Rate Hypothesis? A meta-regression analysis," Journal of
Economic Surveys, 18 (2004), 1-28.
Stanley, T.D., 2005a. Beyond publication bias, Journal
of Economic Surveys 19, 309-45.
Stanley, T.D., 2005b. Integrating the empirical tests of
the Natural Rate Hypothesis: A meta-regression analysis,鈥 Kyklos, 58
(2005), 587-610.
Stanley, T.D. and Jarrell, S.B., 1989. Meta-regression
analysis: A quantitative method of literature surveys," Journal of
Economic Surveys, 3 (1989), 161-170.
Stanley, T.D and Doucouliagos, Hristos, 2010. Picture
this: A simple graph that reveals much ado about research. Journal of Economic
Surveys, 24(2010): 170-91. 听
Stanley, T.D., Jarrell, S. B. and Hristos Doucouliagos,
2010. Could it be better to discard 90% of the data? A statistical paradox. The
American Statistician, 64(2010): 70-77.
Stanley, T.D and Doucouliagos, Hristos, 2012.
Meta-Regression Analysis in Economics and Business. Routledge.
Stanley, T.D, 2013. Does economics add up? An
introduction to meta-regression analysis.鈥 European Journal of Economics and
Economic Policy 10: 207-220.听
Stanley, T.D. and Chris Doucouliagos, 2014.
Meta-regression approximations to reduce publication selection bias, Research
Synthesis Methods 5 (2014), 60-78.
Stanley T. D. and Doucouliagos, H. 2017. Neither fixed
nor random: Weighted least squares meta-regression analysis, Research Synthesis Methods 8, 19-42.听
Stanley, T.D., Doucouliagos, C. and Ioannidis, J.P.A.
2017. Finding the power to reduce publication bias. Statistics in Medicine, 36: 1580-1598.听
Summers, L.H., 1991. The scientific illusion in empirical
macroeconomics. Scandinavian Journal of Economics 93, 129-48.
Turner EH, Matthews AM, Linardatos
E, Tell RA, Rosenthal R. 2008. Selective publication of antidepressant trials
and its influence on apparent efficacy. New
England Journal of Medicine, 358: 252鈥60.
Viscusi,
W.K. 2015. The role of publication bias in estimates of the value of a statistical
life. American Journal of Health Economics 1 (1): 27鈥52.