Journal of Economic Behavior Organization Vol. 43 2000 127–139
Do as you say, say as you do: evidence on gender differences in actual and
stated contributions to public goods
Kelly M. Brown
a,∗
, Laura O. Taylor
b
a
US Environmental Protection Agency, 1200 Pennsylvania Ave., NW, Mail Code 2172, Washington, DC 20460, USA
b
Department of Economics, Andrew Young School of Policy Studies, Georgia State University, Atlanta, GA 30303, USA
Received 10 January 2000; received in revised form 25 January 2000; accepted 9 February 2000
Abstract
Recent work on public goods contributions has examined the relationship between gender and free-riding behavior in studies using laboratory public goods. This research furthers this line of in-
quiry by examining gender as a possible explanation of hypothetical bias, which occurs in valuation studies using real world public goods. Results show that gender differences exist in hypothetical
valuation exercises, but not in real valuation exercises. Further, the results show that hypothetical bias is almost three times larger for males than for females, an important result for researchers
investigating the source of, and solutions for, hypothetical bias. © 2000 Elsevier Science B.V. All rights reserved.
JEL classification: H41
Keywords: Public goods valuation; Gender; Contingent valuation; Experimental economics
1. Introduction
Economists have long recognized that there may be systematic differences in behavior based on observed or unobserved characteristics of individuals. While unobserved char-
acteristics cannot be directly measured, most studies control for observed characteristics that may influence outcomes, such as gender, income, age, and education. The impact of
∗
Corresponding author. Tel.: +1-202-260-4148; fax: +1-202-260-5732. E-mail address:
brown.kellyepa.gov K.M. Brown. 0167-268100 – see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 2 6 8 1 0 0 0 0 1 1 3 - X
128 K.M. Brown, L.O. Taylor J. of Economic Behavior Org. 43 2000 127–139
various characteristics on behavior can provide valuable insight into how and why certain phenomenon occur. For example, recent work using experimental methods has examined
the relationship between gender and free-riding in public goods contributions experiments Brown-Kruse and Hummels, 1993; Nowell and Tinkler, 1994; Seguino et al., 1996; Cadsby
and Maynes, 1998. Each of these studies find evidence of significant free-riding by both females and males, however, the results are contradictory as to which gender exhibits more
free-riding.
In experiments such as those just described, the “public good” consists of a group fund to which subjects contribute some or all of their endowment of tokens in exchange for a return
based on total contributions by the group. These types of public goods are also referred to as laboratory goods, due to their nondescriptive nature. While experiments conducted
with laboratory goods enhance our understanding of behavioral differences in response to various experimental treatments, it is important, to the extent possible, to extend the lab
conditions to the “field”. In the current context, an extension of the lab to the field involves the use of non-laboratory public goods or “real world” public goods, such as public parks
or reserves, in experimental valuation exercises.
In the past, the primary method for valuing non-laboratory public goods has been the contingent valuation method, a survey method that asks subjects to state their willingness to
pay WTP for a particular public good in a contingent, or hypothetical market.
1
Contingent valuation studies often control for gender, but no systematic results as related to gender
have evolved from this literature.
2
This is to be expected as preferences are unique to each particular public good and therefore must be evaluated on a case-by-case basis. While it
is difficult to draw conclusive results regarding gender preferences for public goods across studies using non-laboratory public goods, this does not preclude an analysis of potential
gender-specific behavioral differences in response to various experimental treatments for a given non-laboratory public good.
A recent focus in the contingent valuation literature has been to employ experimental techniques to test the validity of this valuation method e.g. Cummings et al., 1995; Cum-
mings and Taylor, 1999, where validity is the degree to which the contingent valuation survey responses reflect behavior when monetary payments are required as a result of the
valuation process. Typically, in these experiments, subjects are randomly assigned to either a hypothetical or a real treatment. In the hypothetical treatment, subjects are asked to re-
port their WTP or value for a particular public good in a hypothetical survey. In the real treatment, subjects are asked to report their value for the same good, in the same market
scenario, but where actual monetary contributions are paid for the amount stated in the survey. The responses from the two treatments are then compared. It is often, but not
always, the case that significant differences are found in the responses from the two
1
See Hanemann 1994 for an extensive review of the contingent valuation method and Diamond and Hausman 1994 for a critique.
2
For instance, in recent contingent valuation surveys, Cameron and Englin 1997 find evidence that males have significantly higher values for the public good trout stock in lakes and streams in the northeast, while Berrens
et al. 1997 find the opposite result — that males are less likely to support their public good expansion of a university campus cultural center program.
K.M. Brown, L.O. Taylor J. of Economic Behavior Org. 43 2000 127–139 129
markets — stated values are significantly higher in the hypothetical treatments.
3
Differ- ences in responses under hypothetical and real conditions are attributed to hypothetical bias,
which refers to the overstating of true values for a public good when the payment decisions are not binding.
4
While this literature has focused on behavioral differences as related to ex- perimental treatments, no one has examined the potential for gender-related behavioral dif-
ferences in these types of experiments, i.e., for gender differences as related to hypothetical bias.
The potential for gender differences in hypothetical bias is suggested by the work of Gilligan 1982 in which she found that females think about and act on moral dilemmas
in a more inclusive manner, taking relationships into consideration, whereas males are more concerned with obligations and rules. The experimental literature using laboratory
public goods has interpreted her work as implying that females are less likely to free-ride than males Brown-Kruse and Hummels, 1993; Nowell and Tinkler, 1994 or that females
are more likely to respond to context than males Cadsby and Maynes, 1998. We ex- tend this notion and propose that if females are more likely to respond to context than
males, then females would be more likely to respond to the market context than males. Hence, females would be more likely to truthfully reveal their WTP in the hypotheti-
cal treatment, where the true WTP is assumed to be represented by the responses in the real treatment. That is to say, females may be more likely to search their preferences in
response to the interviewer’s request and consider the context of the valuation scenario more closely than males.
5
If this is the case, then we would expect females to exhibit less hypothetical bias than males in experiments using a non-laboratory public good. To
test this hypothesis, this research elicits values for a non-laboratory public good from a sample of subjects in two distinct experimental treatments: a hypothetical treatment and a
real treatment. Results from these two treatments are used to test for differences in values stated by females and males within a treatment; differences in values by treatment within
a gender i.e., for hypothetical bias by gender; and differences in hypothetical bias across genders.
2. Experimental design
