The Importance of Beng Margnal: Gender Dfferences n Generosty 1 Stefano DellaVgna, John A. Lst, Ulrke Malmender, and Gautam Rao Forthcomng, Amercan Economc Revew Papers and Proceedngs, May 2013 Abstract Do men and women have dfferent socal preferences? Prevous fndngs are contradctory. We provde a potental explanaton usng evdence from a feld experment. In a door-to-door solctaton, men and women are equally generous, but women become less generous when t becomes easy to avod the solctor. Our structural estmates of the socal preference parameters suggest an explanaton: women are more lkely to be on the margn of gvng, partly because of a less dspersed dstrbuton of altrusm. We fnd smlar results for the wllngness to complete an unpad survey: women are more lkely to be on the margn of partcpaton. 1 Many thanks to Alec Brandon, Sheng L, Davd Novgorodsky, and Vera te Velde for able research assstance. We are grateful to Rachel Croson and Yan Chen as well as to semnar partcpants at UC Berkeley, CalTech, Chcago, and the ASSA 2013 and ESA 2012 meetngs for valuable comments. 1
In modern economes, prvate organzatons are reled on to provde mportant publc goods and servces. Indeed, snce 1971 ndvdual contrbutons to chartable causes have ncreased from roughly $130 bllon to nearly $300 bllon, or about 2% of GDP. Despte much nterest n understandng the whys? and whats? of gvng, however, fundrasers and academcs alke have faced some persstent puzzles when tryng to predct whch ndvdual wll gve for whch cause. The predctve power of demographc and other ndvdual characterstcs vares wdely across data sets and studes. In the case of gender, the focus of our study, there are conflctng vews on whch s the more chartable gender. In the laboratory, usng varants of the dctator game, Bolton and Katok (1995) fnd no evdence of gender dfferences n generosty, whle Eckel and Grossman (1998) fnd that women share twce as much on average. The same puzzle exsts n feld data. Lookng at the statstcs of blood donaton, women sometmes are overrepresented (e.g., among frst-tme Norwegan blood donors n Msje, Bosnes, and Heer, 2010) and sometmes underrepresented (e.g., n most European countres n the meta analyss of Ban and Gussan, 2010) relatve to men. We provde new evdence from a feld experment that can help reconcle pror conflctng fndngs. We argue that seemng nconsstences n gender-specfc patterns of pro-socal behavor reflect, at least partly, dstrbutonal dfferences n altrusm between genders. Even n cases where men and women do not dffer n ther mean nclnaton to gve, dfferences n heterogenety can lead to a hgher share of women beng on the margn of gvng. Hence, small dfferences n the gvng request (such as n the cost of sayng no) can have szeable effects on women s pro-socal behavor relatve to men. Hence, t s mportant to estmate the wthngender heterogenety n socal preferences to better understand the gender dfferences. Our analyss bulds on recent attempts to te models of pro-socal behavor more closely to 1
emprcal tests, obtanng structural estmates of the underlyng preferences. Specfcally, DellaVgna et al. (2012) use a door-to-door fund-rasng campagn and survey to dsentangle the mportance of warm-glow altrusm versus socal pressure n chartable gvng. Ther estmates suggest that the socal pressure cost of sayng no to a solctor plays an mportant role n hghpressure gvng requests such as door-to-door campagns. In ths paper, we explot the rch desgn n DellaVgna et al. (2012) to estmate the dstrbuton of socal preferences by gender. DellaVgna et al. (2012) compare the ncdence of gvng n a control treatment, n whch subjects receve an unannounced door-to-door vst, to two flyer treatments, n whch subjects are notfed a day n advance of the upcomng door-to-door campagn va a flyer on the door knob. The flyer treatments allow donors who gve due to altrustc motves to sort n; and they allow donors who gve due to socal pressure to sort out. In one of the two flyer treatments, the flyer also ncludes an opt-out box, whch makes t easy to avod the solctor (the solctor does not contact the household f the box s checked). The man fndngs are that () the smple flyer lowers the share answerng the door, relatve to the control group, but does not affect the share gvng; and that () the opt-out opton lowers both the share answerng the door and the share of ndvduals gvng. These fndngs suggest that both altrusm and socal pressure are at play. The desre to avod socal pressure explans the drop n gvng n the opt-out treatment. In ths paper, we decompose these fndngs by gender of the respondents. In Fgure 1 we plot for each treatment the share of households n whch a male person answers and gves to the charty out of all the households contacted; smlarly, we compute a share of females answerng and gvng to the charty. The sum of the two shares equals approxmately the uncondtonal share of gvers out of all the ndvduals contacted. 2 As Fgure 1 shows, the shares of male and 2 For a small fracton of respondents, gender was not recorded. Notce also that we do not observe the gender of the potental gver n the case of households not answerng the door. 2
female gvers are about the same n the baselne treatment. Gven that the shares of males and females answerng the door (not shown) are also smlar n ths treatment, we conclude that generosty n the baselne treatment does not dffer by gender. The shares reman smlar n the smple flyer treatment. In the opt-out treatment, however, women are sgnfcantly less lkely to gve. The decrease n male gvng n the opt-out treatment s nstead small. Fgure 1. Share of households contacted gvng to a charty, by gender and treatment These results provde yet another example of the seemngly nconsstent fndngs n gvng behavor: In a settng where ndvduals cannot (easly) avod a gvng request, we fnd no gender dfferences; n a settng where ndvduals can sort out at a low cost, nstead, the data suggests sgnfcant gender dfferences n gvng behavor. Consderng these fndngs jontly, however, we conclude that women are more responsve to a smple avodance strategy, the opt-out box. We estmate the socal preference parameters separately by gender. Usng all the emprcal moments n the data (not just those dsplayed n Fgure 1), and allowng the key parameters to dffer by gender, we fnd a sgnfcant dfference not only n the mean, but also n the varance of 3
the gender-specfc altrusm dstrbutons. The mpled dstrbutons ndcate that a hgher share of women s on the margn of gvng, and hence responsve to a low-cost opportunty to opt out (snce margnal gvers prefer not to be asked n the frst place). We also fnd evdence of a smlar pattern wth respect to the pro-socal wllngness to answer a survey request. Our fndngs pont to the mportance of consderng dfferences n the overall dstrbuton of socal preferences and, n partcular, margnalty. When put under pressure, women may gve more, and contrbute more to publc goods because they are more lkely to be on the margn, and hence senstve to an extra push. But they may say no f gven a smple opton to do so. The fndng n ths paper are consstent wth the hypothess that women are more malleable or more senstve to socal cues n determnng approprate behavor (see, e.g., Kahn et al., 1971; Croson and Gneezy, 2009). 3 Our fndngs are not nconsstent wth the fndngs cted above that suggest that women are more generous than men. A natural nterpretaton s that the presence of a larger share of margnal gvers leads women to gve more n certan stuatons, but not n others. We would lke to emphasze, though, that the results n ths paper should be seen as suggestve and that more evdence wll be necessary. Fnally, ths paper hghlghts the benefts of the lterature on Structural Behavoral Economcs. Whle the reduced-form fndngs on gender dfferences n gvng are of frst order mportance, t s the estmaton of the underlyng gvng preferences whch suggests a possble explanaton of dfferences n gvng across settngs. I. Framework and Expermental Desgn 3 Our fndngs also complement the prce senstvty of gvng establshed by Andreon and Vesterlund (2001), who show that women are more generous than men when t s relatvely expensve to gve, but that men begn to gve more than women as the prce of gvng decreases. 4
Framework. Consder a two-stage game between a solctor and a potental gver (solctee). 4 In the frst stage, the solctee may receve a warnng of the upcomng solctaton va a flyer at the door, whch she notces wth probablty r (0,1]. In the second stage, the solctor vsts the home. The solctee opens the door wth probablty h [0,1]. If she dd not notce the flyer (or dd not receve one), then h s equal to h 0 (0,1). If she notced the flyer, then she can adjust the probablty to h at a cost c(h), wth c(h 0 ) = 0, c (h 0 ) = 0, and c ( ) > 0. If the solctee opens the door, then she donates g 0. If she does not open the door, there s no donaton (g = 0). In our set-up, a solctee of gender {female, male} has utlty gven by: U ( g) = u ( W g) + a v ( g, G) s ( g). (1) The overall utlty U of an ndvdual of gender s composed of three terms. (For smplcty, we suppress the ndex for each ndvdual.) Frst, prvate consumpton s denoted by u, whch ncludes wealth W mnus the ndvdual s donaton g. We model ths prvate utlty as satsfyng standard propertes: ( u ) > 0 and ( u ) 0. The second term n (1), a v, allows for pure and mpure altrusm (warm glow). In the case of pure altrusm, the agent cares about the total contrbutons to the charty, G + g, where G s the gvng of others. In the case of mpure altrusm, the agent cares about the warm glow from gvng g, and v does not depend on the gvng of others. The altrusm parameter a 0 captures the ntensty of the warm glow (the case a < 0 captures the possblty of spte). Importantly, a s assumed to be heterogeneous across people of gender, wth a dstrbuton F. 4 We only summarze the framework here, drectng the nterested reader to the detals and the slghtly more general model n DellaVgna et al. (2012). 5
The thrd component of (1) s socal pressure. The solctee absorbs a utlty cost s (g) = S (g n g) 1 n g < g 0 for not gvng (or for gvng a small amount), wth ths cost decreasng lnearly n g. The gver does not ncur a socal pressure cost f she s away from home durng the vst. The specal case of S = 0 (no socal pressure) and a = 0 (no altrusm or warm glow) represents the standard model. The model yelds several testable mplcatons. When altrusm domnates socal pressure, the flyer ncreases home presence and gvng relatve to the control group snce some agents seek to meet the solctor. When socal pressure domnates, nstead, the flyer treatments, and especally the opt-out ones, lead to lower rates of answerng the door and of donatons. We allow these effects to dffer by gender. We also model the decson to respond to a survey request, whch s a form of gvng, namely of gvng tme for a survey. We assume that ndvduals of gender receve a utlty sv (whch could be postve or negatve) from completng a 10-mnute survey for no monetary payment. In addton, ndvduals receve utlty from a payment m for completng the survey, and receve dsutlty from the tme cost t of the survey, both of whch are determnstc. The overall utlty from completng a survey hence s sv + m - t. We assume that each ndvdual has a pro-socal value sv drawn from a normal dstrbuton. We structurally estmate the model to provde evdence on the socal preference parameters for men and women. Expermental Desgn. Our desgn combnes two elements. Frst, we rase money n a door-to-door fundrasng drve for two chartes: La Rabda Chldren's Hosptal and the East Carolna Hazard Center (ECU). Second, we conduct surveys of varyng lengths (and varyng 6
monetary ncentves as nducements) to estmate the elastcty of the presence at home and of the response rate to ncentves. In the control treatments, solctors knock on the door or rng the bell and, f they reach a person, proceed through the scrpt. In case of the charty solctaton, they nform the household about the charty (La Rabda or ECU) and ask f they are wllng to make a donaton. In case of the survey solctaton, they nqure whether the household member s wllng to answer a survey about chartable gvng. The solctor nforms the household member about the duraton of the survey (5 or 10 mnutes) and about the payment for completng the survey, f any ($10, $5, or none). In the flyer treatments, the solctor's scrpt s dentcal, but n addton a dfferent solctor leaves a flyer on the doorknob the day before the solctaton. The professonally prepared flyer ndcates the tme of the upcomng fund-rasng (or survey) vst wthn a one-hour tme nterval. In the treatments wth opt-out, these flyers nclude a box that says: Check ths box f you do not want to be dsturbed. If the solctors fnd the box checked, they do not knock on the door. The feld experment took place on Saturdays and Sundays between Aprl 2008 and October 2008. We employed 92 solctors and surveyors, mostly undergraduate students at the Unversty of Chcago. II. Structural Estmates We estmate the parameters of the model usng a mnmum dstance estmator followng the same procedure as n DellaVgna et al. (2012), to whch we refer for detals. We allow some of the key parameters to dffer by gender, namely the parameters determnng the dstrbuton of altrusm a towards the chartes: the mean and the standard devaton of altrusm. We also allow for a dfferent socal pressure cost of turnng down a solctor for males and females. Fnally, we 7
model the wllngness to complete an unpad 10-mnute survey as a normal dstrbuton, wth mean and standard devaton that dffer by gender. The resultng estmates are reported n Table 1 of the Onlne Appendx. Among the most relevant parameters, the standard devaton of the altrusm dstrbuton s smaller for women (17.4) than for men (19.5); n addton, there s a szeable dfference n the mean altrusm towards the out-of-state charty (ECU). Fgure 2 plots the mpled densty of the altrusm dstrbuton for the two chartes, separately for each gender. Noted s the threshold for postve utlty from gvng. 5 As Fgure 2 shows, for the out-of-state charty (ECU) the share of types that are on the margn of gvng that s the types at the threshold s sgnfcantly larger for women. There s a smaller dfference for the n-state charty. The larger densty of estmated types at the margn for women mples that women wll be more responsve to shfts n features of the envronment, or n the cost of sortng out. 5 The actual threshold for gvng s a = (1-S)G and thus depends on the estmated socal pressure cost whch dffers by charty and by gender; ths threshold les between 0 (plotted n the fgure) and G ( = 10), the threshold wth no socal pressure. 8
Fgure 2. Impled dstrbuton of altrusm towards the two chartes, by gender Whle the emphass so far s on gvng of money, what about gvng of tme? We use the feld experment on door-to-door survey completon to estmate the wllngness to complete an unpad 5-mnute survey. Fgure 1 n the Onlne Appendx shows that the share of women completng the survey decreases sgnfcantly from the flyer treatment to the flyer wth opt-out, consstent wth the chartable gvng results. Table 1 n the Onlne Appendx shows that the estmated standard devaton of the pro-socal utlty of completng a survey s agan smaller for females (26.3) than for males (34.0), although the dfference s not statstcally sgnfcant at conventonal levels. Fgure 3 dsplays the mpled dstrbuton of pro-socal utlty from survey completon, whch agan shows that women are more lkely to be at the margnal pont. 6 0.02 Females Males Probablty Densty, f(s) 0.015 0.01 0.005 0-100 -50 0 50 100 Utlty of $0, 10 mn survey (s) Fgure 3. Impled dstrbuton of wllngness to complete a 5-mnute unpad survey. 6 As n the case of gvng money, the fgure plots the threshold for postve wllngness to do a survey; the threshold for survey completon s S. 9
III. Conclusons Ths study uncovers an mportant relatonshp between gender and gvng patterns: there are gender dfferences n socal preferences, but t s mportant to go beyond consderng dfferences n means mportant gender dfferences may be at the margn. Ths leads women to gve more n certan stuatons, but not n others, and also to be more senstve to socal cues. Our study revolves around an expermental desgn that s tghtly lnked to a theory of altrusm and socal pressure. The results naturally permt to mprove our understandng of the quanttatve mportance of each determnant of chartable gvng. Dfferentatng by gender reveals a novel explanaton for seemngly contradctory fndngs n prevous lterature, and our methodology s applcable to other determnants of gvng. Frst, ever- References Andreon, Jm and Lse Vesterlund. 2001. Whch s the far sex? Gender dfferences n altrusm. Quarterly Journal of Economcs 116(4): 293-312. Ban, Marco and Barbara Gussan. 2010. Gender dfferences n gvng blood: a revew of the lterature. Blood Transfuson 8(4): 278-287. Bolton, Gary and Elena Katok. 1995. An expermental test for gender dfferences n benefcent behavor. Economcs Letters 48(1995): 287-292. DellaVgna, Stefano, John Lst, and Ulrke Malmender. 2012. Testng for Altrusm and Socal Pressure n Chartable Gvng, Quarterly Journal of Economcs, 127, 1-56. Eckel, Catherne C. and Phlp J. Grossman. 1998. Are Women Less Selfsh Than Men?: Evdence From Dctator Experments. Economc Journal 108(448): 726-735. Msje, A. H., V. Bosnes, and H. E. Heer. 2010. Gender dfferences n presentaton rates, deferrals and return behavour among Norwegan blood donors. Vox Sanguns 98: e241- e248. 10