Motivating Altruism: A Field Study

21 Pages·2010·0.35 MB·English

Motivating Altruism: A Field Study
∗
Nicola Lacetera Mario Macis
† ‡
University of Toronto Johns Hopkins University
August 12, 2010
Abstract
This paper analyzes the effects of a legislative provision that grants a one-day paid leave of
absence to blood donors who are employees in Italy, using a unique dataset with the complete
donation histories of the blood donors in an Italian town. The across-donor variation in job
market status, and within-donor job switching over time are the sources of variation that we
employtostudywhetherthepaid-day-offincentiveaffectsthefrequencyoftheirdonations. Our
analysisindicatesthattheday-offprivilegeleadsdonorswhoareemployeestomake,onaverage,
aboutoneextradonationperyear. Wediscusstheimplicationsofourfindingsforpoliciesaimed
atreducingtheshortagesinthesupplyofbloodand,moregenerally,forincentivizingpro-social
behavior.
Keywords: Incentives,Altruism,PublicGoodProvision,Pro-socialBehavior,PublicHealth.
JEL Codes: D12, D64, I18.
We thank Oriana Bandiera, Gary Becker, Alberto Bisin, Thomas Buchmueller, Christopher Carpenter, David
∗
Clingingsmith, Stefano DellaVigna, John DiNardo, Luigi Guiso, Daniel Hamermesh, Uri Gneezy, Antonio Lacetera,
Francesca Mazzolari, Hugo Mialon, Felix Oberholzer-Gee, James Rebitzer, Heather Royer, Ariel Rubinstein, Jesse
Shapiro,JoelSlemrod,JustinSydnor,LorenzoZirulia,EzraZuckerman,andseminarparticipantsatIndianaUniver-
sity,NorthwesternUniversity,MIT,UCIrvine,theUniversityofMichigan,ClevelandStateUniversity,CaseWestern
Reserve University, the University of Chicago, the 2008 ASSA Meetings, and the 2008 ASHE Conference for very
useful comments. To protect the privacy of the donors in our database, we have agreed to keep the name of The
Town(aswellasanyotheridentifyinginformation)confidential. WeareextremelythankfultothePresident,Board,
members, and staff of The Town’s unit of the Italian Association of Blood Donors (Associazione Volontari Italiani
del Sangue, AVIS), and to the Head and staff of the Transfusion Unit in The Town’s Hospital, for their precious
collaboration. Raffaella Manna has offered an invaluable contribution to the data collection effort, and Hong Pum
Chung has provided excellent research assistance. This research was conducted in part when Nicola Lacetera was a
faculty member at the Weatherhead School of Management at Case Western Reserve Unibersity, and Mario Macis
wasafacultymemberattheRossSchoolofBusinessattheUniversityofMichigan. FinancialsupportfromtheRoss
School of Business Small Grants Research Fund is gratefully acknowledged.
Rotman School of Management, Department of Strategy. E-mail: [email protected]
†
Carey School of Business. E-mail: [email protected]
‡
1 Introduction
Everyyear, millionsofpeopledevotetime, effort, andmoneytovoluntary, pro-socialactivitiessuch
as donating cash for a cause or organization, helping the elderly and disabled, cleaning beaches, or
donating blood. Yet, for many of these activities, supply is still below societal needs. A notable
example is represented by blood donations. Blood transfusions are required in such situations as
blood loss due to trauma, blood replacement during surgeries, the treatment of premature babies,
andthetreatmentofseveralchronicdiseases. Thereisnoavailablesubstituteforhumanblood,and,
in recent years, the demand has increased dramatically due to, among other causes, an aging popu-
lation and new surgical procedures such as organ transplants (Di Rado, 2004; www.bloodbook.com).
However, blood supply frequently does not keep pace with demand.1 Neither eligibility criteria nor
a lack of information seem likely to explain these shortages. In fact, while on average, in the US
for example, about 50% of adults are typically eligible to donate blood, only between 5-10% do
so at least once a year. Also, information campaigns and communications about shortage periods
are very often conducted by such organizations as the Red Cross, government agencies, schools,
hospitals, etc. An alternative cause to be explored concerns people’s behaviors and incentives.
Individuals might simply not find it worthwhile to dedicate time to donate blood if the private
benefits of donating blood fall short of the opportunity costs. This implies that policies offering
explicit incentives to donate might play a role in encouraging participation in activities that are,
in most countries, based on voluntary and unpaid contributions.
In this paper, we study the effects of Law 584, a legislative provision that gives Italian blood
donorstherighttoapaiddayoffworkonthesamedaythattheydonatebloodorbloodcomponents.
The law applies to all donors who are employed at any private or public organization; salary and
contributions are reimbursed by the state. Our goal is to evaluate whether this legislative provision
induces blood donors to make more donations, and to quantify this effect.
One would not necessarily expect a paid day off to increase blood donations. In fact, while
standard economic theory would deliver this prediction, research in psychology and, more recently,
in economics, argues that extrinsic incentives might crowd out the quantity and quality of the
supplied altruistic activity. For instance, the introduction of economic rewards might create doubts
about the true reason behind pro-social behavior, thus potentially crowding out intrinsic motives.
Economicincentives,therefore,couldbackfireinsteadofreinforcingaltruisticmotivations(Bénabou
and Tirole, 2006; Deci, 1975).2 Given the presence of competing predictions on the impact of
economicincentivesonpro-socialbehavioringeneralandonblooddonationinparticular,empirical
examinations are in order.
1Shortages are frequent in most Western countries and even more severe in developing nations (World Health
Organization, 2009). It is estimated that, worldwide, there is currently a shortage of about 22 million units of blood
(HemoBiotech 2008).
2TheseviewslendsupporttotheearlyclaimsofTitmuss(1971)aboutthenegativeeffectsofpayingforblood,in
termsofbothlowerqualityofbloodandlowerquantitybecausepeoplewouldrefrainfroma"paid"prosocialactivity.
Titmuss’ 1971 book The Gift Relationship was very influential in marking the end of a paid blood supply system in
the U.S. in the 1970s (Healy, 2006; Shearmur, 2007).
2
Our analysis is based on a unique, longitudinal dataset comprising the individual histories of
blood donations of the whole population of donors in an Italian mid-sized town ("The Town"
hereinafter). In addition to demographic information and the number and dates of donations
made by about 2,600 unique donors in the periods 1985-89 and 2002-06, the database includes
information on the donors’ labor market status, and occupations. Because our data do not include
the years both before and after the introduction of the policy, we cannot evaluate the effects of
the policy on the extensive margin of donation (i.e., on inducing more people to become blood
donors). However, the data allow studying whether blood donors are responsive to the paid-day-off
incentive. In particular, our empirical strategy exploits cross-sectional variation in donors’ labor
market statuses, and, crucially, variation in job-switching by donors over time.
We first look at the choice of the donation day by the donors in our sample. Consistent with
abundant anecdotal evidence, we find that donors who are employees are significantly more likely
to donate on Fridays compared to other categories of donors. Because donations can be made only
in the morning in The Town’s hospital, and because most employees do not work on Saturday,
donating on a Friday maximizes the number of consecutive days off (2.5) a donor can enjoy if he or
shetakesadvantageof Law584.3 Individualswhoareoutofthelaborforce(i.e., notaffectedbythe
possibility of a day off) tend to distribute their donations uniformly during the week. Employers
and self-employed individuals, who also do not benefit from the policy, cluster their donations
on those days in which they do not work; store owners disproportionately donate on Mondays,
when stores in The Town are, by law, closed; and other self-employed donors donate mostly on
Saturdays, when their businesses do not operate. We interpret these patterns as indicating that
economic considerations play an important role in influencing donor behavior. In particular, the
"Friday effect" we detected for employees suggests that a substantial share of this group of donors
exploits the full potential benefit from the day-off provision. As a further corroboration of this
view, we find that employees show a preference for donating the day before major holidays, and
that the take-up rates of the incentive, as represented by the percentage of donors who request a
document attesting their donation to be presented to their employer, average 70%, with spikes of
80% on Fridays and Mondays.
We then turn to the core question of the paper: Does the day-off provision of Law 584 induce
blood donors to make more donations? We exploit the facts that the incentive benefits only donors
who are employees, that our data include information on donors’ jobs, and that a subset of the
donors in our sample change labor market status. The longitudinal nature of our data enables us
to perform regressions of each donor’s donation frequency on his or her labor market status with
individual fixed effects, which absorb any heterogeneity in time-invariant personal attributes that
might be correlated with donation behavior (including "intrinsic" altruism). Our identification
strategy, therefore, uses within-donor occupational shifts to determine whether changing labor
market status is associated with different donation frequencies. We find that when donors are in
3Anumberofstudiesinhumanresourcemanagementshowthatworkers,infact,preferworkschedulesthatallow
for more consecutive days off (Facer and Wadsworth, 2008; Moores, 1990; Pierce and Dunham, 1992).
3
the "employee" status (i.e., when they are eligible to benefit from the day-off incentive) they make
about one extra blood donation per year. This effect is robust to a variety of specifications and
sampleselections, someofwhichlimittheconcernthatotherchangesthatmightbeassociatedwith
changing labor market status, such as family structure and health, might be driving the results.
Importantly, not only do we find a positive average effect but also that the effect is opposite
and symmetric for the two treatment groups; donors who go from being non-employees to being
employees increase their donation frequency, and those who used to be employees and become non-
employees reduce their frequency by a similar amount. The evidence, therefore, is consistent with
the paid-day-off provision stimulating more donations. As a consequence, removing this policy (a
measure, infact, recentlyadvocatedbytheItalianEmployers’Associationaswell asbytheCentral
Government) would likely result in a reduced number of donations by existing donors.
In addition to providing novel findings from a new source of data, our study complements the
existingexperimental literatureontheimpactof explicitincentivesontheperformanceof altruistic
activities in at least two other ways.4 First, the fact that most industrialized countries often make
it illegal to reward blood donations makes it difficult to analyze the issue empirically in the field.
To the best of our knowledge, our study is the first to analyze the actual behavior of an entire
population of blood donors in response to a naturally occurring incentive. Second, the individuals
in our field study are free to not enjoy the economic benefits, for instance, by choosing the day of
theweekonwhichtodonate. Thefactthattheincentiveisnaturallyoccurringandthatindividuals
are free to not benefit from it reduces concerns about social desirability bias and limited sorting in
the experimental literature (Harrison and List, 2004; Lazear, Malmendier, and Weber, 2010; Levitt
and List, 2007).
Theremainderofthepaperisstructuredasfollows. Section2describestheinstitutionalcontext
of this study and the data. Section 3 presents the empirical analysis and findings. Section 4 offers
a summary of the findings and considerations on their policy implications.
2 Institutional Background and Data
The data used in this study originate from hand-collected information on the entire blood donation
histories of all donors in an Italian town located in the north-central part of the country.5 Before
4EarlylaboratoryexperimentsbyDeciandhiscollaboratorsfoundthataddingexplicitrewardsfortheperformance
of activities that are motivated by intrinsic reasons leads to a reduction in the performance of those activities (Deci,
1975). Similar findings have been obtained by, among others, Frey and Oberholzer-Gee (1997) and Gneezy and
Rustichini (2000). Gneezy and Rustichini, however, find that "large enough" incentives do stimulate pro-social
behavior. With specific reference to blood donation, Mellstrom and Johannesson (2008) document that Swedish
female college students are less willing to undertake a health test to be eligible to donate blood if offered monetary
incentives. In partial contrast to these results, Goette and Stutzer (2008), in a field experiment in Switzerland, find
that offering lottery tickets to promote donations increases turnout at blood drives. Other studies have focused on
other extrinsic motives for pro-social activities, such as the quest for social recognition. See, for example, Andreoni
and Bernheim (2009); Ariely, Bracha, and Meier (2008); Harbaugh (1998a, 1998b); Lacetera and Macis (2010a);
Nowak and Sigmund (2000); Polborn (2007); Price (2003); and Wedekind (1998).
5The demographic, social, and economic characteristics of The Town’s population are highly representative of
the overall Italian urban population. Statistics comparing The Town with other Italian towns under a number of
4
describing the data in detail, we provide some background information on the blood donation
system in Italy and in The Town, and we describe the day-off incentive introduced by Law 584.
2.1 Blood donation in Italy and in The Town
Blood donation in Italy isorganized through blood banks run by volunteer donor associations. The
associations have a central headquartersas well as town-level units. Todonate blood, an individual
is required to become a member of one of these associations. The three major associations, which
are present in different parts of the country and do not compete with one another, are Associazione
Volontari Italiani del Sangue (AVIS),withabout1.1millionmembersin2007, Federazione Italiana
delle Associazioni Donatori di Sangue (FIDAS), with about 400,000 members (Caligaris 2007),
and Fratres, with 150,000 members (in 2000).6 The affiliation is to a local unit of the national
associations, and blood donors predominantly donate in the town where "their" unit is located.
In The Town, blood donation is managed by the largest blood donor association, AVIS, and
donations of either whole blood or blood components take place at The Town’s public hospital,
Monday through Saturday from 8 to 11 a.m. Donors do not make appointments, and donate on a
"first come, first served" basis.
In Italy, only individuals between 18 and 65 years of age are allowed to donate blood. Italian
law limits to the frequency of donations of blood and blood components. Whole blood can be
collected once every 90 days from male donors and once every 180 days from females.7 The time
required for a platelet or plasma donation is about one hour, compared to an average of twenty
minutes for a whole blood donation. Including the time to reach the donation site, the waiting
time before the donation and the resting time at the hospital after the donation (which is higher
for whole blood donation), on average, a blood donor should expect a commitment of about two
hours.
2.2 An explicit incentive to blood donors: A one-day paid leave of absence for
employees
According to the National Law 584 of 1967, all donors who are employed at any private or public
organization have the right to a paid day off work on the same day that they donate blood or
socio-economic characteristics are available upon request.
6Blooddonationsrunthroughbloodbanksandvoluntarydonorassociations(whichwerepresentsincethe1920s)
havebecometheofficialblooddonationandcollectionsysteminItaly,afterabriefperiod,followingtheendofWorld
War II, when the Red Cross played a prominent role. Similar blood bank systems exist in other countries, such
as Denmark, Greece, Norway, Portugal, and Spain. In the U.K., France, and Ireland, in contrast, the organization
of blood donation is run by the State. The Red Cross, finally, is the dominant organization that manages blood
donation in such countries as Belgium, The Netherlands, Germany, and the U.S. In the U.S., however, the system is
moreheterogeneousandcompetitive,comprisingtheRedCross,bloodbanks,andhospitalsdirectlymanagingblood
donations. See Healy (2006) on the different organizational modes of blood donations.
7Donors can give platelets once every 30 days and plasma once every 14 days. Conversations with doctors and
AVISofficialsinTheTownrevealedthatthetypeofdonationis"exogenous"toadonor’schoice. Donors,ingeneral,
join the Association to donate whole blood, and are assigned to donating blood components if they are not eligible
to donate whole blood (e.g., if they have insufficient iron in their blood), or if there is some urgent need for a blood
component.
5
blood components. Employers are refunded by the state for the related salary expenses they
incur (including social security and other contributions). From the employee’s standpoint, this
provision is equivalent to sick days in addition to those that he or she has by contract, with an
important difference. Unlike an illness absence, when the employee is required to stay home (a
medical inspector can be sent to check for the sickness claim), this requirement does not hold in
the case of an absence for blood donation.8 Employees in other countries are typically allowed time
during work hours to donate blood, usually without deductions in salary or accrued leave. Usually,
however, these provisions just give donors the material time to make their donation, and, typically,
the donor has to return to work after donating. The benefit from Law 584 goes well beyond giving
some rest to donors after their donation, and, therefore, it represents an explicit reward to blood
donors.
The typical work week of an Italian employee is Monday to Friday. Most businesses, as well as
most public workplaces, do not operate on Saturdays. Some exceptions are represented by hospital
doctors, teachers (because in Italian public schools, attended by the near totality of students, only
Sundays are off), and some employees in public workplaces such as City Hall clerks in offices open
to the public. A further notable exception is given by stores, most of which are closed, by law, on
Monday mornings and are open on Saturdays.
2.3 The data
UsingbothAVIS’sandTheTown’shospital’sarchives,weidentifiedalloftheAssociation’smembers
(and, therefore, all of The Town’s blood donors) from 1985 to 2006. For each individual donor,
we obtained the entire donation history over this 22-year period. Information on donors includes
sex, age, blood type, and the date when each individual became a donor. Crucially for the goal of
this paper, we have information, for a subset of donors, on their occupational statuses, and jobs.
AVIS does not update its members’ occupational status on a regular (e.g., yearly) basis. Within
our period of interest, updates were made in 1985 and 2002. We therefore limit our analysis to two
subperiods, 1985through1989and2002through2006, attributingthesamejobstatusintheinitial
years to the following four years. This introduces the possibility that, for some donors and in some
years, occupation is recorded with error. Our results, however, are essentially unchanged when we
restrict the analysis only to the years 1985 and 2002, when occupation is accurately measured.
Table 1 presents descriptive statistics on the donors. Over the years 1985-89 and 2002-06, 2,614
unique individuals donated blood in The Town, 759 of whom were females. The number of active
donors has increased over time, going from 543 in 1985 to 1,282 in 2006, and so has the fraction of
female donors, from 24.5% in the mid 1980s to 28.8% in more recent years. The pool of donors has
aged slightly over time, moving from an average age of 38 to about 40 years. The average number
8Also similar to the rules regarding sick days is the absence of a formal requirement to inform the employer in
advance of the intention to donate blood (and to not go to work) by an employee. The employer cannot refuse, in
any case,to "concede" theone-day leave. This does notexcludethat, on an informalbasis, employees can giveprior
notice to their employers.
6
of donations per year is 2.4, and the median number of donations over the entire period is 13. Of
the 826 donors who were active in the period 1985-89, 286 were still active in 2002-06. Panel B
of Table 1 shows descriptive statistics by labor market status.9 In 1985-89, about 65% of donors
(61% in 2002-06) were paid employees, 9% (12% in 2002-06) were self-employed, and 26% (27% in
2002-06) were out of the labor force. The majority of non-employed donors are students, and this
is reflected in the relatively younger age of these donors.
[Table 1 about here]
3 Empirical Analysis
We perform our empirical analysis in two steps. First, we provide evidence consistent with the fact
that blood donors take into account the economic benefits and costs from their donation decisions,
and, as standard theories would predict, they try to maximize the difference between the two. We
do so by examining the choice of donation days by donors of different labor market statuses. Our
secondstep, andthecentralpartofthisstudy, istodocumenthowtheLaw584/1967, byincreasing
the economic benefits of donating for employees, leads to an increase in blood donations.
3.1 Economic considerations, Law 584 and the choice of donation days
Donating on different days of the week entails different costs and benefits for different categories of
workers. Donors who are paid employees would need to ask for time off, or they could donate on a
day when they do not work. Law 584, however, givesthemthe option of taking a day off when they
makeablooddonation. Thiscreatesdifferentialbenefitsondifferentweekdays. Sincedonationscan
be made only in the morning in The Town’s hospital, and because most employees do not work on
Saturday, donating on a Friday (if leisure is taken as a good) maximizes the number of consecutive
days off (2.5) that a donor-employee can enjoy. A number of studies show that workers, in fact,
favor work schedules with more consecutive days off (Facer and Wadsworth, 2008; Moores, 1990;
PierceandDunham, 1992). Therefore, onewouldexpectdonors-employeestoshowapreferencefor
donating on Friday, if they respond to the incentive in the sense of making the most out of it. The
behavior of this group can be contrasted to that of other categories of donors, who do not enjoy the
day-off benefit. First, donors who are out of the labor force (e.g., students, housekeepers, retirees)
should not display strong preferences over different days of the week, because costs and benefits
are very similar. Second, for donors who own and operate a business ("self-employed" hereinafter),
the cost of donating varies across days of the week; they would incur a cost if they donated on a
working day, but not on the day their business is closed. In particular, also this group should not
display any particular preference for donating on Friday.
9Donors whose occupational status could not be determined because of the incompleteness of the AVIS records
do not significantly differ from the rest of the donors in terms of age and other observable characteristics.
7
Figure 1 reports the distribution of donations across the days of the week by donors’ labor
market statuses, pooling the data from the two periods 1985-89 and 2002-06.10 These distributions
areconsistentwithdonorstakingintoaccountcostsandbenefitsconsiderationswhenchoosingwhen
to donate, and with employees, in particular, trying to receive the highest net economic benefit.
Overall, Saturdayemergesasthedayinwhichmostdonationsoccur—aboutfourpercentagepoints
above a case of uniform distribution of donations across days (i.e., 100%/6 = 16.70%). There are,
however, substantial differences in the distribution of donation days across job categories. For
employees, a higher-than-average number of donations, around 20%, take place on Fridays. The
"excessfraction"ofFridaydonations(fractionFridayminus 16.70%)is+3.26%foremployees, with
a statistically significant t-ratio of 8.77, against 0.96% (not statistically different from zero) for
−
the unemployed and donors out of the labor force, and a statistically significant 4.90% for the
−
self-employed(t-ratio = 6.29). Donationsbytheself-employedarestronglyclusteredonMondays
−
and Saturdays. Specifically, we find that store owners’ donations are clustered on Mondays, when
stores are closed, and the other employers’ donations are concentrated on Saturdays, when the
other businesses are closed. Finally, the donations by donors who are out of the labor force are
uniformly distributed across weekdays. Finally, the donations by donors who are out of the labor
force are virtually uniformly distributed across weekdays.
[Figure 1 about here]
We also have some direct evidence that donors-employees actually take advantage of the day-
off incentive. Upon request, The Town’s hospital provides the donors with official documentation
that they can then present to their employer to prove that they donated blood (the employer then
presents the same document to the state when asking for reimbursement). The Town’s hospital,
unfortunately, does not keep complete records of these documents. We obtained partial records
(about half a year) for 2006, which show that, on average, Monday through Friday about 70%
of donors-employees requested official documentation that they donated. This indicates that they
actually took the day off rather than donating and then returning to work. Spikes in the take-up
rate (about 80%) are found on Mondays and Fridays. Interestingly, the take-up rate is 30% on
Saturday; therefore, a non-negligible fraction of donors-employees who choose Saturday also enjoy
the day off. Conversations with the doctors and hospital administrators confirmed that take-up
rates are very high, especially on Fridays, and our results confirms their perception that donors-
employees take advantage of Law 584.
In sum, our analysis of the choice of donation days by groups of donors based on their labor
market statuses indicates that all categories of donors take into account cost-benefit considerations
when deciding when to donate. In particular, a substantial fraction of donors-employees shows a
10The distribution of donations across weekdays for all donors is virtually identical to that for donors with non-
missing labor market status. In the remainder of the paper, we will limit our attention to donors with non-missing
labormarketstatusinformation. Also,wereplicatedalloftheanalysisperformedinthissectionseparatelybyperiod
(1985-1989 and 2002-2006), and the results were very similar.
8
preference for Friday, which, thanks to the day-off incentive, allows them to maximize the consec-
utive number of days off work that they can obtain by donating.11
3.2 Does the day-off incentive lead to more donations?
The previous analysis presented suggestive evidence that donors-employees choose when to donate
in a way that is consistent with exploiting the full potential of the benefit (i.e., maximizing the
numberofconsecutivedaysoff). However,itispossiblethattheLawinducesdonorstochangetheir
preferred donation day while leaving their total number of donations unchanged. In the remainder
of the paper, we assess whether the incentive actually causes donors who are entitled to the benefit
to make more donations than they would otherwise.
3.2.1 Descriptive evidence
We begin by asking whether donors who are employees donate more or less frequently, in general,
compared with other donors. Figure 2 shows the entire distribution of the number of donations
per year by labor market status: employees, self-employed and out-of-labor-force donors. The
differences in the distribution of donation frequencies across these groups are substantial. The
percentage of donors making just one donation a year is about 27% among employees, 33% for
the self-employed, 37% for the non-employed. Conversely, while 43% of employees make 3 or more
donations a year, this fraction is just 36% among the self-employed and 31% for those out of the
labor force. This descriptive evidence is strongly suggestive that the paid-day-off provision might
be inducing donors-employees to donate more often than they would without the incentive. The
regression analyses that follow will test the causal nature of, and quantify, this effect.
[Figure 2 about here]
3.2.2 Identification strategy
Assessing the causal relationship between the provisions of Law 584 and an increase in donation
frequency using different labor market statuses requires that we control for both observable charac-
teristics and unobservable heterogeneity (including "intrinsic" altruism) that might be correlated
with the propensity to donate blood. The richness of our data and, crucially, their longitudinal
nature allows us to do so. In particular, we have multiple observations for each donor; therefore,
we perform donor-fixed-effects regressions, which absorb any unobservable and time-invariant het-
erogeneity. Further, we exploit the fact that a set of donors who were active donors in the 1985-89
11All of the above findings are robust to regression analyses. In regressions not reported here, we have estimated
probit models for which the outcome variable is whether an individual donated on Friday, and multinomial logit
models forwhich the fouroutcomes are donating on (1) Monday, (2) Tuesday through Thursday, (3) Friday, and (4)
Saturday. The explanatory variables included indicators forthe labormarket status ofthe donor, as well as controls
for demographic characteristics and year effects. The results are available upon request. We obtain similar results
when we look at the propensity of donors to donate the day right before a series of national holidays (i.e., such days
look like Fridays). This further corroborates our interpretation of the results.
9
period are still active in the 2002-06 period, and a subset of these donors changed labor market
status in the second period relative to the first. Thus, we use within-donor occupational shifts
to determine whether changing labor market status is associated with different donation frequen-
cies. In other words, we implement a difference-in-differences methodology as part of which we use
donors who are active in both periods and have not changed labor market status as the control
group, and where the two "treatment" groups are: (a) donors who were self-employed or out of the
labor force in the first period and became employees in the second period, and (b) donors who were
employees in the first period and became self-employed or left the labor force in the second period.
If the day-off incentive does play a role in the donors’ choices of their frequency of donation, we
expect to observe a change in the donation frequency of donors in groups (a) and (b) compared
to donors in the control group. Specifically, we should see an increase in the donation frequency
of group (a) and a decrease in the donation frequency of group (b) relative to the group of donors
who do not change labor market statuses. As with any difference-in-differences estimation, our
identifying assumption is that, in the absence of the policy, the average outcomes for the "treated"
(i.e., occupation switchers) and "control" (i.e., those who do not change occupation) groups would
have followed similar paths over time. In the analysis below, we discuss whether this assumption
is likely to be satisfied in our setting, and we perform a series of robustness checks.
3.2.3 Regressions results
Main results The right-hand side panel of Table 1 reports descriptive statistics on the sample of
the 286 donors who were active in both periods 1985-89 and 2002-06. Of the 153 donors for whom
wehavelabormarketstatusinformationinbothperiods, 97maintainthesamelabormarketstatus
in 2002-06 as in 1985-89, while the remaining 56 changed status. More than 60% of male donors
who were below the age of 40 in 1985 were still active in 2002.12
As a first step toward establishing a causal relationship between the day-off incentive and the
frequency of donation, in columns (1) and (2) of Table 2 we report the results of individual fixed-
effects regressions of the number of donations made by each donor each year on a dummy variable
equal to 1 if a donor is an employee at a given point in time, and 0 otherwise. In column (1),
the sample consists of all donors observed in either 1985-89 or 2002-06 and with known labor
market status whereas, in the remaining columns, we restrict the sample to donors who are active
in both periods. At the bottom of each column, we report the mean of the dependent variable, for
comparison. The regressions include a set of controls consisting of period effects (for 1985-89 and
2002-06), year dummies, and age-group dummies. The coefficient on the employee indicator is the
difference-in-differences estimator, identified, in our fixed-effects regressions, out of the donors who
switch labor market status, transitioning in or out of employee status.
12Reaching the age limit is what mostly explains why donors cease to donate and hence drop out of our database
between 1985-89 and 2002-06. Logit regressions of the probability for a donor who was active in 1985-89 to be still
active in 2002-06 confirm this. In particular, controlling for the age of donors in 1985-89, employment status does
not have a significant effect on the probability of being still active in 2002-06. These regressions are not reported
here but are available upon request.
10