Checking the Evidence for Declining Discount Rates

Szekeres, Szabolcs (2020): Checking the Evidence for Declining Discount Rates.

Abstract

A numerical model is used to experimentally compute certainty equivalent discount rates (CERs) of risk neutral and risk-averse decision makers. Investors are characterized by utility functions of the constant-intertemporal-elasticity-of-substitution (CIES) type. Stochastic interest rates are generated using a Cox, Ingersoll & Ross (CIR) type model, calibrated to 1992-2017 US three-month Treasury Bill rates. The paper replicates empirical studies providing evidence for declining discount rates (DDRs) and tests claims regarding risk averse CERs in a descriptive discounting context. It is shown that DDRs as proposed by Weitzman are based on a fallacy. The reviewed papers seeking empirical evidence of DDRs repeat the mistake. Risk averse CERs can be decline with time because of portfolio effects. If these are low, risk averse CERs are slightly lower than risk neutral ones but not secularly declining.

• Item Type: MPRA Paper
• Language: English
• Keywords: Weitzman-Gollier puzzle; declining discount rates; discounting
• Subjects: D - Microeconomics > D6 - Welfare Economics > D61 - Allocative Efficiency ; Cost-Benefit Analysis; H - Public Economics > H4 - Publicly Provided Goods > H43 - Project Evaluation ; Social Discount Rate

References

Arrow, Kenneth J. and Robert C. Lind (1970), “Uncertainty and the Evaluation of Public Investment Decisions” The American Economic Review, Vol. 60, No. 3 (Jun., 1970), pp. 364-378, https://www.jstor.org/stable/1817987.

Freeman, M.C. et al. (2015), “Declining Discount Rates and the Fisher Effect: Inflated Past, Discounted Future,” Journal of Environmental Economics and Management, Vol. 73, pp. 32-49, https://dx.doi.org/10.1016/j.jeem.2015.06.003.

Gollier, Christian and James K. Hammitt (2014) “The Long-Run Discount Rate Controversy,” The Annual Review of Resource Economics, 2014. 6:273–95, https://doi.org/10.1146/annurev-resource-100913-012516

Gollier, Christian, Phoebe Koundouri, Theologos Pantelidis (2008) “Declining Discount Rates: Economic Justifications and Implications for Long-Run Policy” Economic Policy, Volume 23, Issue 56, 1 October 2008, Pages 758–795, https://doi.org/10.1111/j.1468-0327.2008.00211.

Groom, B., P. Koundouri, E. Panopoulou, & T. Pantelidis (2007) “Discounting the Distant Future: How much does model selection affect the certainty equivalent rate? Journal of Applied Econometrics, 22, 641-656.

HMT (2003). Guidelines on Cost Benefit Analysis. HM Treasury, UK.

Newell, Richard and William Pizer (2000) “Discounting the Distant Future: How Much Do Uncertain Rates Increase Valuations?” Discussion Paper 00-45, Resources for the Future, Washington, DC.

Nordhaus, William (2019). “Climate Change: The Ultimate Challenge for Economics.” American Economic Review 2019, 109(6): 1991–2014, https://doi.org/10.1257/aer.109.6.1991

Szekeres, Szabolcs (2013). The “Weitzman-Gollier puzzle" is not a paradox but a mistake, and it is most likely moot. Open Science Repository Economics, Online (open-access), e23050448. http://www.open-science-repository.com/economics-23050448.html

Szekeres, Szabolcs (2017) Checking Gollier and Weitzman’s solution of the “Weitzman–Gollier puzzle”. Economics Discussion Papers, No 2017-11, Kiel Institute for the World Economy. http://www.economics-ejournal.org/economics/discussionpapers/2017-11

Szekeres, Szabolcs (2019) Why expected discount factors yield incorrect expected present values. Journal of Applied Economic Sciences, Volume XIV, Spring, 1(63): 282-292. http://cesmaa.org/Extras/JAESArchive

Weitzman, M.L. (1998), “Why the far distant future should be discounted at its lowest possible rate.” Journal of Environmental Economics and Management, 36, 201-208.

Weitzman, M. L. (2001) Gamma discounting. American Economic Review 91:260–271