Abstract
We use instrumental variables for estimating the causal effect of beliefs on contributions in repeated public good games. The effect is about half as large as suggested by ordinary least squares. Thus, we present evidence that beliefs have a causal effect on contributions, but also that beliefs are endogenous. We compare the causal, belief-based model of contributions to alternative models based on matching the previous contributions of others and responding to one’s deviation from the average in the previous round. The causal, belief-based model performs well, indicating that beliefs have a central role in determining contributions.
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Notes
Croson (2007) has subjects play two ten round games, but the restart creates a structural break.
There is a literature about belief elicitation. Croson (2000), and Gaechter and Renner (2010) study belief elicitation in public good games. Costa-Gomes and Weizsaecker (2008), Nyarko and Schotter (2002), and Rutstrom and Wilcox (2009) examine belief elicitation in other games. Our objective in this paper is to address the endogeneity associated with a common approach to eliciting beliefs. We do not claim to have found an ideal method of belief elicitation.
Subjects reported their beliefs to the nearest 0.1 LD. Admittedly, incentives for accuracy were lost when guesses were not within 1 LD of the actual amounts. However, strictly incentive compatible mechanisms, such as the one used by Croson (2007), where payoffs are inversely related to the absolute differences between guesses and the actual amounts, also provide increasingly small rewards for accuracy as guesses diverge from the actual amounts. We favored a mechanism heavily rewarding accuracy within small margins of the actual amounts. Subjects received positive amounts 50 % of the time (634/1,280), so on average, they had a reasonable chance of receiving payoffs for their guesses.
That is, subjects made contribution decisions and reported their beliefs on the same screen in z-Tree (Fischbacher 2007).
Fischbacher and Gaechter (2010) do not specify the order in which subjects choose contributions and report beliefs.
The results are very similar to those obtained using multiple other methods, including random effects and tobit models, as well as a model estimated by feasible generalized least squares, accounting for an autoregressive component in the error structure of the multiple observations from each subject.
An F-test of equality of coefficients is not straightforward because the standard errors of the Arellano-Bond model are not computed in the usual way.
A third potential source of bias is omitted variables. However, fixed effects (in the case of specification (2)) and differencing (in the case of specification (3)) account for time invariant omitted variables.
Not shown, but available upon request.
We are unaware of other experimental economics papers using lagged variables as instruments for endogenous regressors. However, using lagged variables as instruments is not new. In fact, the Arellano-Bond method uses lagged variables as instruments for the lagged dependent variable.
Sargan and Basmann test statistics are not available following cluster-robust estimation. The p-values given are those calculated following 2SLS estimation with a variance/covariance matrix that is not cluster-robust. However, this only makes it more likely that the null hypothesis is rejected.
References
Arellano, M., & Bond, S. (1991). Some tests of specification for panel data: Monte Carlo evidence and an application to employment equations. Review of Economic Studies, 58(2), 277–297.
Ashley, R., Ball, S., & Eckel, C. (2010). Motives for giving: a reanalysis of two classic public goods experiments. Southern Economic Journal, 77(1), 15–26.
Baker, R. J. II, Walker, J. M., & Williams, A. W. (2009). Matching contributions and the voluntary provision of a pure public good: experimental evidence. Journal of Economic Behavior & Organization, 70(1–2), 122–134.
Bellemare, C., Kroeger, S., & van Soest, A. (2008). Measuring inequity aversion in a heterogeneous population using experimental decisions and subjective probabilities. Econometrica, 76(4), 815–839.
Bellemare, C., Sebald, A., & Strobel, M. (2011). Measuring the willingness to pay to avoid guilt: estimation using equilibrium and stated belief models. Journal of Applied Econometrics, 26(3), 437–453.
Croson, R. (2007). Theories of commitment, altruism and reciprocity: evidence from linear public goods games. Economic Inquiry, 45(2), 199–216.
Croson, R. (2000). Thinking like a game theorist: factors affecting the frequency of equilibrium play. Journal of Economic Behavior & Organization, 41(3), 299–314.
Croson, R., Fatas, E., & Neugebauer, T. (2005). Reciprocity, matching and conditional cooperation in two public good games. Economics Letters, 87(1), 95–101.
Costa-Gomes, M. A., Huck, S., & Weizsaecker, G. (2010). Beliefs and actions in the trust game: creating instrumental variables to estimate the causal effect, Working paper, University of Aberdeen.
Costa-Gomes, M., & Weizsaecker, G. (2008). Stated beliefs and play in normal-form games. Review of Economic Studies, 75(3), 729–762.
Dufwenberg, M., Gaechter, S., & Hennig-Schmidt, H. (2011). The framing of games and the psychology of play. Games and Economic Behavior, 73(2), 459–478.
Ferraro, P. J., & Vossler, C. A. (2010). The source and significance of confusion in public goods experiments. The B.E. Journal in Economic Analysis & Policy, 10, 53 (Contributions).
Fischbacher, U. (2007). z-Tree: Zurich toolbox for ready-made economic experiments. Experimental Economics, 10(2), 171–178.
Fischbacher, U., & Gaechter, S. (2010). Social preferences, beliefs, and the dynamics of free riding in public goods experiments. American Economic Review, 100(1), 541–556.
Gaechter, S., & Renner, E. (2010). The effects of (incentivized) belief elicitation in public goods experiments. Experimental Economics, 13(3), 364–377.
Guttman, J. M. (1986). Matching behavior and collective action: some experimental evidence. Journal of Economic Behavior & Organization, 7(2), 171–198.
Ham, J. C., Kagel, J. H., & Lehrer, S. F. (2005). Randomization, endogeneity and laboratory experiments: the role of cash balances in private value auctions. Journal of Econometrics, 125(1–2), 175–205.
Keser, C., & van Winden, F. (2000). Conditional cooperation and voluntary contributions to public goods. Scandinavian Journal of Economics, 102(1), 23–39.
Neugebauer, T., Perote, J., Schmidt, U., & Loose, M. (2009). Selfish-biased conditional cooperation: on the decline of contributions in repeated public goods experiments. Journal of Economic Psychology, 30(1), 52–60.
Nickell, S. (1981). Biases in dynamic models with fixed effects. Econometrica, 49(16), 1417–1426.
Nyarko, Y., & Schotter, A. (2002). An experimental study of belief learning using elicited beliefs. Econometrica, 70(3), 971–1005.
Rutstrom, E., & Wilcox, N. (2009). Stated beliefs versus inferred beliefs: a methodological inquiry and experimental test. Games and Economic Behavior, 67(2), 616–632.
Stock, J. H., & Yogo, M. (2005). Testing for weak instruments in linear IV regression. In D. W. K. Andrews & J. H. Stock (Eds.), Identification and inference for econometric models (pp. 80–108). New York: Cambridge University Press.
Sugden, R. (1984). Reciprocity: the supply of public goods through voluntary contributions. Economic Journal, 94(376), 772–787.
Wooldridge, J. M. (2010). Econometric analysis of cross section and panel data (2nd ed.). Cambridge: MIT Press.
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Financial support from Worcester Polytechnic Institute (WPI) is gratefully acknowledged.
The author thanks John Spraggon, Younghwan Song, two anonymous reviewers, Editor Jakob K. Goeree, seminar participants at Union College, and conference participants at the 2011 CEAs in Ottawa, the 2011 International ESAs in Chicago and the 2011 North American ESAs in Tucson for excellent comments and suggestions. Financial support from Worcester Polytechnic Institute (WPI) is gratefully acknowledged.
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Smith, A. Estimating the causal effect of beliefs on contributions in repeated public good games. Exp Econ 16, 414–425 (2013). https://doi.org/10.1007/s10683-012-9345-5
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DOI: https://doi.org/10.1007/s10683-012-9345-5