Does Context Matter More for Hypothetical Than for Actual Contributions?

Transcription

1 Dscusson Paper Seres March 2008 EfD DP Does Context Matter More for Hypothetcal Than for Actual Contrbutons? Evdence from a Natural Feld Experment Francsco Alpzar, Fredrk Carlsson, and Olof Johansson-Stenman

2 The Envronment for Development (EfD) ntatve s an envronmental economcs program focused on nternatonal research collaboraton, polcy advce, and academc tranng. It supports centers n Central Amerca, Chna, Ethopa, Kenya, South Afrca, and Tanzana, n partnershp wth the Envronmental Economcs Unt at the Unversty of Gothenburg n Sweden and Resources for the Future n Washngton, DC. Fnancal support for the program s provded by the Swedsh Internatonal Development Cooperaton Agency (Sda). Read more about the program at or contact nfo@efdntatve.org. Central Amerca Envronment for Development Program for Central Amerca Centro Agronómco Tropcal de Investgacíon y Ensenanza (CATIE) Emal: centralamerca@efdntatve.org Chna Envronmental Economcs Program n Chna (EEPC) Pekng Unversty Emal: EEPC@pku.edu.cn Ethopa Envronmental Economcs Polcy Forum for Ethopa (EEPFE) Ethopan Development Research Insttute (EDRI/AAU) Emal: ethopa@efdntatve.org Kenya Envronment for Development Kenya Kenya Insttute for Publc Polcy Research and Analyss (KIPPRA) Narob Unversty Emal: kenya@efdntatve.org South Afrca Envronmental Polcy Research Unt (EPRU) Unversty of Cape Town Emal: southafrca@efdntatve.org Tanzana Envronment for Development Tanzana Unversty of Dar es Salaam Emal: tanzana@efdntatve.org

3 Does Context Matter More for Hypothetcal Than for Actual Contrbutons? Evdence from a Natural Feld Experment Francsco Alpzar, Fredrk Carlsson, and Olof Johansson-Stenman Abstract We nvestgated the mportance of the socal context for people s voluntary contrbutons to a natonal park n Costa Rca, usng a natural feld experment. Some subjects make actual contrbutons whle others state ther hypothetcal contrbuton. Both the degree of anonymty and nformaton provded about the contrbutons of others nfluence subject contrbutons n the hypotheszed drecton. We found a substantal hypothetcal bas wth regard to the amount contrbuted. However, the nfluence of the socal contexts s about the same when the subjects make actual monetary contrbutons as when they state ther hypothetcal contrbutons. Our results have mportant mplcatons for valdty testng of stated preference methods: a comparson between hypothetcal and actual behavor should be done for a gven socal context. Key Words: Envronmental valuaton, stated preference methods, voluntary contrbutons, anonymty, conformty, natural feld experment JEL Classfcaton Numbers: C93, Q Envronment for Development. All rghts reserved. No porton of ths paper may be reproduced wthout permsson of the authors. Dscusson papers are research materals crculated by ther authors for purposes of nformaton and dscusson. They have not necessarly undergone formal peer revew.

4 Contents Introducton 1 Desgn of the Experment.. 3 Experment Results. 7 Conclusons.. 13 References. 15 Lst of Tables Table 1: Expermental Desgn for All Treatment Combnatons 5 Table 2: Summary Results of Contrbutons for Dfferent Treatments 8 Table 3: Contrbuton Dfferences between Dfferent Treatments Dvded along Hypothetcal and Actual Contrbuton Treatments 9 Table 4: Regresson Analyss of Hypothetcal and Actual Contrbutons to the Natonal Park... 12

5 Does Context Matter More for Hypothetcal Than for Actual Contrbutons? Evdence from a Natural Feld Experment Francsco Alpzar, Fredrk Carlsson, and Olof Johansson-Stenman Introducton Context often matters even when conventonal economc theory predcts that t should not (Tversky and Kahneman 1981). In ths paper, we am to quantfy the effect of two types of contexts on people s voluntary contrbutons to a natonal park n Costa Rca: the degree of anonymty, and nformaton about the contrbutons of others. We used a natural feld experment to nvestgate whether the nfluence of socal context s dfferent for hypothetcal contrbutons than for actual contrbutons. In the lterature, there s ample evdence of context effects on envronmental valuaton, for example, that framng n terms of scenaro descrpton, payment vehcle, or the degree of anonymty nfluences survey responses (Blamey et al. 1999; Russel et al. 2003; Lst et al. 2004). Schkade and Payne (1994) used a verbal protocol methodology where they let people thnk aloud when answerng a contngent valuaton queston, and concluded that people seem to base ther responses on ssues other than what the envronmental valuaton lterature typcally assumes. For example, the authors found that before the respondents provded an answer, more than 40 percent of them consdered how much others would be wllng to contrbute. However, much of the expermental evdence suggests that context also matters n stuatons nvolvng actual payments or contrbutons (Hoffman et al. 1994; Cookson 2000; McCabe et al. 2000). More specfcally, there s ample evdence of so-called condtonal cooperaton, meanng that many people would ndeed lke to contrbute to an overall good cause, such as a publc good, but only f other people contrbute ther far share (Fschbacher et al. 2001; Frey and Meer 2004; Gächter 2006; Shang and Croson 2006). In lght of ths, the fndng by Schkade and Payne (1994) may not be that surprsng. Francsco Alpzar, Envronment for Development Center, Tropcal Agrcultural and Hgher Educaton Center (CATIE), 7170 Turralba, Costa Rca, (emal) falpzar@cate.ac.cr, (tel) ; Fredrk Carlsson, Department of Economcs, Unversty of Gothenburg, Box 640, SE Gothenburg, Sweden, (emal) Fredrk.Carlsson@economcs.gu.se, (tel) ; Olof Johansson-Stenman, Department of Economcs, Unversty of Gothenburg, Box 640, SE Gothenburg, Sweden, (emal) Olof.Johansson@economcs.gu.se, (tel)

6 One nterestng queston s whether respondent behavor s more senstve to context (such as the percepton of the behavors of others) when makng a hypothetcal but realstc choce, compared to makng a choce that nvolves an actual payment. Some have suggested that ths dfference may be large (e.g., Bertrand and Mullanathan 2001), whereas others, such as Hanemann (1994), beleve that the dfference s small (f t exsts at all) and that context affects behavor generally and not just n survey-based valuaton studes. 1 The emprcal evdence for comparng the effects of context s rather scarce. Moreover, one may also queston the result of comparng lab experments wth hypothetcal and actual money, f the purpose s to measure how closely they resemble real lfe behavor. Levtt and Lst (2007) argue that lab experments wth real money are useful for dentfyng mechansms, snce the possblty of control s much hgher compared to conventonal emprcal analyss. At the same tme, results of lab experments should be nterpreted wth more care when t comes to generalzng about quanttatve fndngs outsde the expermental context. Instead, Levtt and Lst advocate feld experments, where the subjects are observed wthout knowng that they are takng part n an experment. Ths paper presents the results of a natural feld experment to use the termnology of Harrson and Lst (2004) n Costa Rca, where we nvestgated the mportance of anonymty wth respect to the solctor, and nformaton about the contrbutons of others. 2 In partcular, we quantfed and compared these effects for two samples: one based on hypothetcal contrbutons and one on actual contrbutons. The effect of anonymty has been nvestgated prevously for both hypothetcal and actual treatments (Legget et al. 2003; Lst et al, 2004; Soetevent 2005). For example, Legget et al. (2003) found that a stated wllngness to pay was approxmately 23 percent hgher when the contngent valuaton survey was admnstered through face-to-face ntervews rather than beng self-admnstered by the respondents. Lst et al. (2004) looked at chartable contrbutons both hypothetcal and actual to the Center for Envronmental Polcy Analyss at the Unversty of Central Florda, usng three dfferent nformaton treatments: (1) the responses were completely anonymous, (2) the expermenter knew the response, and (3) the whole group knew the response. 1 Note that we do not refer to the ssue of hypothetcal bas,.e., that there s a dfference between stated and real contrbutons for a gven context. A large number of studes found a hypothetcal bas, although the occurrence and extent of t depended on a number of factors, such as the type of good and the elctaton method. For an overvew, see Lst and Gallet (2001). 2 For other recent feld expermental studes on determnants of chartable gvng, see, e.g., Lst and Luckng-Reley (2002), Landry et al. (2006), and Karlan and Lst (2007). 2

7 Whle they found the largest share of yes responses when the whole group was nformed of the response (followed by when only the expermenter knew the response), they also found that the dfferences among the nformaton treatments were smlar n the hypothetcal and the actual votng treatments. A contrbuton of ths paper tested whether ths fndng could be generalzed to a feld experment settng. The effect of nformaton about the contrbutons or behavors of others has been nvestgated n several feld experments (Alpzar et al. 2007; Frey and Meer 2004; Shang and Croson 2006; Heldt 2005; Martn and Randall 2005). For example, Shang and Croson (2006) nvestgated how nformaton about a typcal contrbuton to a rado staton affected subject contrbutons. They found that ther hghest reference amount ($300) mpled a sgnfcantly hgher contrbuton than gvng no nformaton at all. The drecton for smaller amounts ($75 and $180) was the same, although not statstcally sgnfcant. As far as we know, no prevous study has looked drectly at how nformaton about the contrbutons of others affects stated contrbutons. 3 Consequently, ths paper s the frst to analyze the dfference between a hypothetcal and actual treatment wth respect to the nfluence of provded nformaton about the contrbutons of others. The body of ths paper s organzed as follows: secton 2 presents our feld experment desgn, secton 3 the correspondng results, and secton 4 has the conclusons. 2. Desgn of the Experment The experment and survey looked at contrbutons by vstng nternatonal toursts to the Poas Natonal Park (PNP) n Costa Rca n We put great effort nto ensurng that the stuaton was realstc and credble; there was nothng ndcatng that ths was a unversty study to analyze people s behavor. Ths s potentally very mportant, as noted by Levtt and Lst (2007), because a perceved expermental stuaton may hghlght people s sense of dentty or self-mage to a larger extent than outsde the expermental stuaton (cf. Akerlof and Kranton 2000). 3 However, one explanaton of so-called yea-sayng the tendency of some respondents to agree wth an ntervewer s request regardless of ther true vews (Mtchell and Carson 1989) s that respondents beleve that the suggested bd n a contngent valuaton survey contans nformaton about the behavors of others. If so, one may nterpret observed yea-sayng bas as an ndcaton of the nfluence of the contrbutons of others. Several papers have nvestgated the presence of yea-sayng; see, for example, Blamey et al. (1999); and Holmes and Kramer (1995). 3

8 The fve people admnsterng the experment were offcally regstered ntervewers of the Costa Rcan Toursm Board. We began by nvtng all potental solctors by emal to an ntal screenng meetng where we evaluated ther personaltes and abltes to speak fluently n both Spansh and Englsh. Of ten possble canddates ntervewed, we chose fve who fulflled all our requrements. The fve solctors partcpated randomly n all parts of the experment. Nevertheless, we controlled for solctor effects n the regresson analyss. The solctors underwent extensve, pad tranng both n the classroom and n the feld. Once they were ready to start, we dedcated a whole week to testng ther performance and to makng small adjustments n the survey nstrument. In addton, there were daly debrefng questons and regular meetngs wth the whole team to make sure that all solctors were usng the same exact wordng of the scenaros. The solctors approached nternatonal toursts after they had vsted the volcano crater, whch s the man attracton of the park. The toursts were approached at a staton outsde the restaurant and souvenr shop, whch was decorated wth the logos of PNP, the Natonal System of Protected Areas (SINAC), and the Tropcal Agrcultural and Hgher Educaton Center (CATIE). 4 The solctors wore unforms wth the logos of PNP and CATIE and carred formal dentfcaton cards that ncluded a photo and sgnatures of park authortes. The unforms were smlar to those used by the PNP park rangers. A formal letter authorzng the collecton of contrbutons and the survey was also clearly vsble. Only nternatonal toursts who could speak ether Spansh or Englsh partcpated n the experment. The subjects were approached randomly, and only one person n the same group of vstors was approached. Selecton of partcpants was a key element of the tranng sessons and we checked daly for subject selecton bases. No correctons were requred after the plot sessons. Subjects were frst asked f they were wllng to partcpate n an ntervew about ther vst to the PNP. No menton of voluntary contrbutons took place at ths stage, so we expected that partcpaton was not affected by monetary consderatons. Overall, partcpaton rates were hgh (more than 85 percent each day). Once t was establshed that the subjects were nternatonal toursts and that they had already vsted the crater, the solctors proceeded wth the ntervew. Before the experment, the subjects were asked a few questons regardng ther vst to 4 The Tropcal Agrcultural Research and Hgher Educaton Center had the man responsblty for data collecton. 4

9 Costa Rca and to the natonal park. The solctors also had standardzed reples to the most common questons regardng the survey, the experment, the nsttutons nvolved, etc. For further nformaton, the partcpants were advsed to talk to the man supervsor of the contrbuton campagn. Table 1 Expermental Desgn for All Treatment Combnatons Hypothetcal contrbutons Actual contrbutons Total Anonymous Nonanonymous Anonymous Nonanonymous No reference contrbuton 62 observatons 62 observatons 62 observatons 63 observatons 250 Reference contrbuton: $2 63 observatons 62 observatons 61 observatons 63 observatons 249 Reference contrbuton: $5 60 observatons 61 observatons 62 observatons 62 observatons 249 Reference contrbuton: $10 62 observatons 62 observatons 62 observatons 62 observatons 249 Total 247 observatons 247 observatons 247 observatons 250 observatons 991 In total, 991 subjects partcpated n the experments. We conducted experments both wth hypothetcal and wth actual contrbutons. For each type of experment, we used anonymous and non-anonymous treatments, as well as three dfferent reference levels for the stated contrbutons of others. Table 1 summarzes the expermental desgn for all treatments. To avod cross-contamnaton, we decded to conduct the hypothetcal and actual treatments durng the same perod, but never smultaneously. Ths meant that all solctors worked on hypothetcal contrbutons durng one part of the day and actual contrbutons durng the other part of the day. Ths orderng was randomly decded. All the other dfferent treatments were conducted smultaneously, and they were randomly dstrbuted both n terms of tme of day and among solctors. The dfferent treatments requred slght modfcatons of the ntervewng scrpt, as outlned below, but we were very careful to lmt the dfferences between the treatments. Subjects also receved a card where they could read the scenaro and the nstructons for the voluntary contrbuton. The experment began wth the same sentence for both treatments: I wll now read to you some nformaton about the fundng of natonal parks n Costa Rca. Here s a paper wth the nformaton I wll read. After ths, the partcpants were told about the man purpose of the request for a contrbuton. The wordng that was unque for the hypothetcal treatment s n parentheses, whereas the correspondng wordng for the actual treatment s n brackets. 5

10 The system of natonal parks n Costa Rca s now sufferng from the lack of funds to acheve a good management of the parks, both for bodversty conservaton and toursm. Avalable funds are smply not enough and natonal parks are tryng to obtan new funds. We are now (researchng) [testng] a system at Poas Natonal Park where vstors can make donatons to the park. The entrance fee (would reman) [remans] the same seven dollars but people (would have) [have] the possblty to make voluntary donatons to the park n addton to the fee. Contrbutons (would) [wll] be used to mprove the standard of lvng of park rangers, to provde better trals, and to make sure that ths beautful and unque ecosystem s well taken care of. The effect of a socal reference pont was nvestgated by provdng the subjects wth nformaton about typcal prevous contrbutons by other vstors. If a reference pont was provded, the followng sentence was read: We have ntervewed toursts from many dfferent countres and one of the most common donatons has been 2 / 5 / 10 US dollars. We obtaned the monetary reference values from a plot study conducted at the same park mmedately before our man experment; thus, the reference nformaton s not based on decepton. In the treatments wth no mentoned reference amount, we smply omtted the above sentence. Fnally, the actual request for a contrbuton dffered dependng on whether the contrbuton was to be anonymous or not. In the anonymous cases, subjects were asked to go nto a prvate area that was part of our ntervewng staton and wrte down ther contrbuton on a pece of paper (provded) or put ther contrbuton (f any) n a sealed envelope and then nto a small ballot box. Ths way ther contrbuton was completely anonymous to the solctor. 5 The followng text was then read: (If there was a possblty, how much would you donate?) [How much are you wllng to donate to ths fund?] Please go to the booth and (wrte down the amount of money you would lke to donate f you had the possblty) [put the amount of money you would lke to donate n the envelope]. Remember that donatons wll be used exclusvely to mantan and mprove the Poas Natonal Park, as descrbed before. When you are done, (please fold t twce) [please seal the envelope] and put t n ths box. Do not show t to me, because your (stated donaton) [donaton] should be completely anonymous. Please put the (paper) [envelope] n the box even f you do not wsh to donate anythng. 5 In order for us to dentfy the contrbutons and lnk them to the other questons n the questonnare, an ID number was wrtten on the envelope. The subjects were nformed about the ID number and the reason for t. The mportant feature s that the solctor was not able to observe the contrbuton, not even afterwards. 6

11 We provded a locked ballot box nto whch the contrbutons were put. Ths box was actually part of the ntervewng staton used for the expermental sesson. In the non-anonymous settng, the followng text was read: (If there was a possblty, how much would you donate?) [How much are you wllng to donate to ths fund?] Remember that donatons wll be used exclusvely to mantan and mprove the Poas Natonal Park, as descrbed before. When you are done readng, please (tell me the amount of money you would lke to donate f you had the possblty) [gve the envelope and your contrbuton to me so that I can count and regster your donaton before sealng the envelope. Please return the envelope even f you do not wsh to donate anythng]. In ths treatment, the subjects were aware that the solctor was observng each contrbuton. In addton to the dfferences descrbed above, everythng else was dentcal n all ntervews, and we expected the typcal varatons of a feld experment (weather, type of tourst, etc.) to affect our results randomly. 3. Experment Results Table 2 presents the basc results of the experments. The most strkng fndng was the large amount of hypothetcal bas. In the actual contrbuton treatment, 48 percent of the subjects chose to contrbute and the average contrbuton was $2.43, whle n the hypothetcal contrbuton treatment, 87 percent of the subjects stated that they would contrbute an average of $ Thus, the average contrbuton n the hypothetcal treatment was more than three tmes as large as n the actual treatment, and the dfference s hghly sgnfcant usng a smple t-test. The large hypothetcal bas came as no surprse. Frst, there s much evdence that suggests the exstence of a hypothetcal bas (Lst and Gallet 2001) unless certan measures are taken, e.g., the use of so-called cheap talk scrpts (e.g., Cummngs and Taylor 1999). We dd not take any such measures. Second, there s also evdence that the hypothetcal bas s 6 As always, n stated preference surveys wth an open-ended queston, a number of respondents state very hgh numbers. These responses have a strong nfluence on the average contrbuton. We have therefore dropped observatons statng contrbutons larger than $100. The lowest contrbuton we deleted was $450. In the actual contrbuton experment, the hghest contrbuton was $50. 7

12 Table 2 Summary Results of Contrbutons for Dfferent Treatments Treatment No. of observatons Share postve contrbuton Condtonal average contrbuton (std) Sample average contrbuton (std) Hypothetcal contrbutons Total Anonymous Non-anonymous No reference Reference: $ Reference: $ Reference: $ Actual contrbutons Total Anonymous Non-anonymous No reference Reference: $ Reference: $ Reference: $ (10.56) 8.97 (11.69) 8.49 (9.26) (15.81) 6.00 (6.94) 7.08 (5.82) (10.08) 5.09 (5.74) 5.00 (5.65) 5.17 (5.84) 6.48 (7.45) 3.46 (3.81) 4.82 (3.24) 5.92 (7.05) 7.58 (10.27) 7.92 (11.35) 7.25 (9.07) 9.77 (15.07) 5.28 (6.80) 6.20 (5.92) 9.07 (10.03) 2.43 (4.70) 2.37 (4.62) 2.48 (4.80) 2.90 (3.58) 1.92 (3.32) 2.10 (3.21) 2.78 (5.20) partcularly large for publc goods, compared to prvate goods (Lst and Gallett 2001; Johansson- Stenman and Svedsäter 2007). The sgns of the effects of dfferent socal contexts were largely as expected. For example, f people choose to donate, they wll donate substantally more f they are gven a $10-8

13 reference pont nstead of a $2-reference pont. Ths held for both the hypothetcal and the actual treatments. The effect of anonymty was less clear. In the case of actual contrbutons, the condtonal contrbuton was larger n the non-anonymous case, as one mght expect, whereas the opposte pattern held n the hypothetcal case. However, the man purpose here was nether to nvestgate the extent of hypothetcal bas nor to quantfy the mportance of varous knds of socal contexts, but nstead to nvestgate the response dfferences between the hypothetcal and actual treatments wth respect to these socal contexts. Table 3 summarzes these dfferences. Table 3 Contrbuton Dfferences between Dfferent Treatments Dvded along Hypothetcal and Actual Contrbuton Treatments Contrbuton dfferences between samples Hypothetcal contrbutons Non-anonymous Actual contrbutons Anonymous Share postve contrbuton - 3 percentage ponts 1 percentage pont Condtonal contrbuton -$0.48 (-5%) $0.17 (3%) Sample contrbuton -$0.67 (-8%) $0.11 (5%) Reference $2 No reference Share postve contrbuton 5 percentage ponts 8 percentage ponts Condtonal contrbuton -$5.76 (-49%) -$3.02 (-47%) Sample contrbuton -$4.49 (-46%) -$0.98 (-34%) Reference $5 No reference Share postve contrbuton 5 percentage ponts -1 percentage pont Condtonal contrbuton -$4.66 (-40%) -$1.66 (-26%) Sample contrbuton -$3.57 (-36%) -$0.80 (-28%) Reference $10 No reference Share postve contrbuton 6 percentage ponts 2 percentage ponts Condtonal contrbuton -$1.54 (-13%) -$0.56 (-9%) Sample contrbuton -$0.7 (-7%) -$0.12 (-4%) The frst part n table 3 reports the comparson between non-anonymous and anonymous treatments. For example, for hypothetcal contrbutons, the share of people contrbutng was 3 9

14 percentage ponts lower n the non-anonymous treatment, and the sample average contrbuton was $0.67, or 8 percent, lower. By comparng the second and thrd columns, we could compare the response dfference between hypothetcal and actual contrbutons for a gven socal context treatment. Although there were ndeed dfferences between the hypothetcal and actual treatments, they were rather small (partcularly compared to the hypothetcal bas). More mportantly, although we excluded some extreme outlers, the mean values were stll rather senstve to a few observatons. In order to deal wth the outler problem, we also present the results from a regresson analyss. The dependent varable, contrbuton, was censored snce t equaled zero for a substantal fracton of the subjects. In addton, there are two ssues of nterest here: whether to contrbute anythng at all, and how much to contrbute, gven a postve contrbuton. Snce there were good reasons to consder these as two dfferent decsons, a basc Tobt model would be napproprate. We therefore used a smple two-stage model. The decson whether to contrbute anythng or not was modeled wth a standard probt model. The decson concernng how much to contrbute, gven a postve contrbuton, was modeled wth a regresson model that used only subjects wth a postve contrbuton. For completeness, we calculated both a standard OLS regresson and a robust regresson, where the latter put a lower weght on outlers. 7 The base case n the regresson models was gven by actual contrbutons n the anonymous treatment wth no menton of a reference contrbuton. In table 4, margnal effects for the two estmated models are presented together wth the total margnal effect,.e., ncludng the effects of the probt stage. All margnal effects are calculated at sample means. 8 The total margnal effect s calculated as: [ ] P[ C > 0] E C x = x [ C > 0] E C E C + [ C > 0] x [ > 0] P C where E [ C ] s the expected contrbuton of ndvdual, [ C > 0], P s the probablty that ndvdual contrbutes anythng at all, and x s a covarate. Both the probt model and the regresson models nclude a constant. 7 We used the rreg command n STATA. Frst, a standard regresson was estmated, and observatons wth a Cook s dstance larger than one were excluded. Then, the model was estmated teratvely: t performed a regresson, calculated weghts based on absolute resduals, and regressed agan usng those weghts (STATA 2005). See Rousseeuw and Leroy (1987) for a descrpton of the robust regresson model. 8 For the probt model, the margnal effect for dummy varables was for a dscrete change of the varable from zero to one. 10

15 We presented four dfferent models for the contrbuton decson: two where the dependent varable was the contrbuton (one wth a standard OLS regresson and one wth a robust regresson), and two where the dependent varable was the natural logarthm of the contrbuton (one wth a standard OLS regresson and one wth a robust regresson). In all models, we pooled the hypothetcal and actual contrbuton data. In order to correct for an overall hypothetcal bas, we ncluded a dummy varable for the hypothetcal experment. To be able to dentfy response dfferences between the hypothetcal and actual contrbuton treatments wth respect to the dfferent socal contexts (the man task of ths paper), we created nteracton varables between the dummy varable for hypothetcal treatment and the dummy varables for each socal context. The results are presented n table 4. The coeffcent assocated wth the hypothetcal experment was, as expected, large and hghly sgnfcant n all models, reflectng a large hypothetcal bas. The four coeffcents n table 4 below show the nfluence of the dfferent socal contexts for the actual contrbuton experment. Interestngly, there was no dfference between the anonymous and non-anonymous treatments. These results can be compared to Lst et al. (2004), who found that the proporton of subjects votng n favor of a proposal to fnance a publc good was sgnfcantly lower n a treatment where subjects were completely anonymous (20 percent), compared to a treatment where the solctor observed the behavor (38 percent). The lkelhood of a postve contrbuton was also hgher n the treatment wth a $2-reference contrbuton, compared to gvng no reference nformaton at all, whereas the correspondng effect on condtonal contrbutons was negatve. It thus appears that whle provdng a low reference pont ncreases the probablty of a postve contrbuton, the average sze of the contrbuton s lower when compared to not provdng a reference pont. Our man nterest lay n the last four coeffcents. They reflected the dfference n socal context effects between the hypothetcal and actual experments, where we controlled for an overall dfference between the two experments. For non-anonymty, we dd not fnd any sgnfcant dfference between the hypothetcal and actual experments for any of the presented models. For reference contrbutons, we dd not fnd any sgnfcant dfference between the hypothetcal and actual experments for the $2- and $5-reference contrbutons; ths appled both to the probablty of a postve contrbuton and to the sze of the condtonal contrbuton. For the $10-reference contrbuton, we dd not fnd any sgnfcant dfference n most models. However, n the case of a robust regresson where the dependent varable was the contrbuton, we found a sgnfcant dfference (at the 10-percent level). For the $10-reference level, the ncrease n contrbutons was $1.40 hgher n the hypothetcal experments, compared to the 11

16 Table 4. Regresson Analyss of Hypothetcal and Actual Contrbutons to the Natonal Park The coeffcents reflect margnal effects evaluated at sample means. All models nclude an ntercept, solctor dummy varables, and subject characterstcs varables. P-values are n parentheses. Dependent varable: Contrbuton Dependent varable: Log (contrbuton) Probt OLS regresson Robust regresson OLS regresson Robust regresson Hypothetcal contrbuton (HC*) Non-anonymous treatment Treatment wth a $2 reference contrbuton Treatment wth a $5 reference contrbuton Treatment wth a $10 reference contrbuton HC* non-anonymous treatment HC* treatment wth a $2 ref. contrbuton HC* treatment wth a $5 ref. contrbuton HC* treatment wth a $10 ref. contrbuton Solctor dummy varables Subject characterstcs varables (0.000) (0.738) (0.086) (0.752) (0.791) (0.347) (0.977) (0.333) (0.359) Condtonal effect (0.001) (0.951) (0.073) (0.404) (0.848) (0.772) (0.169) (0.162) (0.586) Total effect (0.000) (0.891) (0.373) (0.481) (0.943) (0.585) (0.315) (0.461) (0.907) Condtonal effect (0.003) (0.790) (0.001) (0.916) (0.865) (0.620) (0.299) (0.417) (0.074) Total effect (0.000) (0.970) (0.304) (0.800) (0.793) (0.687) (0.554) (0.888) (0.101) Condtonal effect (0.000) (0.791) (0.000) (0.504) (0.372) (0.997) (0.811) (0.408) (0.248) Total effect (0.000) (0.721) (0.112) (0.546) (0.666) (0.525) (0.875) (0.946) (0.206) Condtonal effect (0.002) (0.673) (0.000) (0.486) (0.612) (0.488) (0.840) (0.533) (0.252) Total effect (0.000) (0.946) (0.026) (0.535) (0.866) (0.786) (0.925) (0.820) (0.206) Included Included Included Included Included Included Included Included Included Included Included Included Included Included Included Included Included Included 12

17 ncrease n contrbutons was $1.40 hgher n the hypothetcal experments, compared to the actual experments. Ths fndng s far from robust, however, and n the standard OLS regresson, the sgn was reversed (although the effect s nsgnfcant). 9 In the two models wth the log of contrbuton as the dependent varable, both the OLS and the robust regressons showed that the nfluence of the $10-reference level on the condtonal contrbuton was about 20 percent hgher n the hypothetcal treatment compared to the actual treatment, but the coeffcent was nsgnfcant n both cases. 4. Conclusons Ths paper dscusses a test for whether people are more nfluenced by socal contexts n a hypothetcal experment than n an experment wth actual monetary mplcatons. We based the test on a natural feld experment wth voluntary contrbutons to a natonal park n Costa Rca. We found a large hypothetcal bas. However, we dd not fnd any sgnfcant dfferences between hypothetcal and actual contrbutons wth respect to the effects of socal context, except for one treatment and one regresson model for whch a sgnfcant effect at the 10-percent level was observed. The results suggest that socal context s mportant n general and s not a phenomenon that s prmarly present n stuatons that do not nvolve tradeoffs wth actual money. Ths can be compared to the fndngs by Lst et al. (2004), who observed smlar effects of dfferent nformaton treatments for hypothetcal and actual votng treatments. Our results consequently mply a generalzaton of the fndngs by Lst et al. to a feld experment settng most mportantly and whch also encompasses provded reference contrbutons. Our results also have mportant mplcatons for valdty tests of stated preference methods, such as the contngent valuaton method. A frequently used test, whch s typcally consdered relable, s to compare the hypothetcal responses from a stated preference method to a correspondng setup that nvolves actual money (e.g., Cummngs et al. 1997; and Blumenschen et al. 2007). However, t follows from the results here that treatments that nvolve actual monetary payments are also vulnerable to framng effects, whch calls such tests nto queston; ths concluson parallels Lst et al. (2004). Moreover, we have n addton shown that people appear to be almost as vulnerable to framng effects even f they do not know that they are partcpatng n an experment. Thus, the result of the valdty test s not only vulnerable to the framng of the stated 9 The underlyng reason for ths rather large dfference between the robust regresson and the OLS regresson results was, of course, the nfluence of a few large contrbutons.

18 preference formulatons (use of cheap talk scrpts, etc.), but also to the context n whch the actual behavor s observed. If the ultmate purpose of the test s to fnd out the extent to whch the stated preference method reflects the valuaton n realty, t s mportant that the actual comparson case resembles as closely as possble the socal context n whch the valuaton typcally takes place n realty. Future research based on other samples and dfferent stuatons s encouraged n order to test the extent to whch the conclusons here are robust. 14

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