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OCR for page 221
Appendix A
Adapting the Easterlin-Crimmins
Synthesis Mode} to
Sub-Saharan Conditions
This appendix explores whether the Easterlin and Cnmrnins (1985) synthesis
model of reproductive decisions provides an appropriate framework for the
study of contraceptive use in Africa. The synthesis perspective centers
attention on an individual couple of reproductive age. What is at issue is the
number of children the couple expects to bear if no contraception is em-
ployed, compared with the number of births that are wanted or demanded.
If the potential supply of births exceeds the quantity demanded, there exists
a motivation for contraceptive use. Thus, the model draws together three
essential elements: reproductive capacity, the demand for reproductive out-
comes, and the principal means contraception by which couples bring
actual reproductive outcomes into agreement with their reproductive desires.
Socioeconomic determinants enter the model via the concept of de-
mand, which encompasses factors such as the risks of child mortality and
the access to and costs of contraceptive methods. Although the Easterlin-
Cnmmins model is usually taken to be a model of lifetime fertility or of the
behavior of ending or limiting reproduction, and their socioeconomic deter
1Easterlin and Crimmins (1985) introduce a second concept of demand, having to do with
the desired number of births in the absence of mortality risk, that assumes away all monetary,
time, or psychic costs of contraception. As discussed in Montgomery (1987), this hypothetical
or notional concept of demand plays no essential part in the synthesis model. Hence, the
concept of demand employed in the material that follows is conventional, in that mortality
risks and contraceptive costs are hypothesized to affect the desired number of births.
221
OCR for page 222
222
FACTORS AFFECTING CONTRACEPTIVE USE
minants, the model can be used equally well to understand the demand for
spacing births. As discussed below, the spacing-limiting distinction has to
do with the length of the decision period envisioned in the synthesis model.
Potential supply and demand may be compared over a period as short as the
monthly reproductive cycle or as long as the reproductive span itself. In
addition to its connections to birth spacing and limiting, the length of deci-
sion periods is also an issue in the model's treatment of proximate determi-
nants other than contraception.
In effect, the synthesis perspective divides the full range of proximate
determinants of fertility (e.g., contraception, involvement in sexual union,
postpartum nonsusceptibility, and induced abortion) into three mutually ex-
clusive groups. First, there are the exogenous proximate determinants such
as individual fecundability, which set constraints on reproductive capacity.
By exogenous we mean those determinants that are not under the control of
the couple during the decision period under consideration. This category of
determinants defines the couple's potential supply of births. The second
group of proximate determinants comprises the effective and less effective
methods of contraception; these are clearly endogenous in being, at least in
part, the means by which the couple puts into effect its reproductive de-
mands.2 In the third category of dete~-~inants fall those behaviors that
cannot be neatly classified as either exogenous or endogenous in nature.
One could include breastfeeding intensity and duration in this third cat-
egory, together with postpartum sexual abstinence, participation in a repro-
ductive union, and spousal separation. The degree of erogeneity displayed
by such behaviors will depend on the length of the decision period in ques-
tion and on the specific character of the economic, social, and cultural
organization.
By distinguishing among categories of proximate determinants, direct-
ing attention to the category of contraceptive use, and providing an organ~z-
ing framework that shows how reproductive constraints and demands are
expressed in contraceptive use, the synthesis perspective has much to rec-
ommend it. Its usefulness in this regard was recognized by an earlier
National Research Council report on determinants of fertility in developing
countries (Bulatao and Lee, 1983~.
2At this point we should remark on the place of induced abortion in the conceptual frame-
work developed below. It seems that by all accounts, the psychic and access costs of abortion
in sub-Saharan Africa are of such a magnitude that it is rarely employed in marriage, although
recent evidence indicates that abortion is increasing (Coeytaux, 1988). We regard these costs
as being grouped with other factors that implicitly determine the demand for contraception.
There is little need to single out the costs of abortion as a distinct motivation for contraception,
unless (1) these costs, or components of the costs, can be measured; and either (2) the costs
vary significantly across socioeconomic or demographic groups; or (3) the costs are expected
to change in the future, perhaps as a result of policy.
OCR for page 223
APPENDIX A
223
In what follows we make a few brief comments, primarily of a theoreti-
cal nature, on the elements of the analytic framework as applied to Africa.
The bulk of the discussion concerns the relations between the concepts of
supply and demand and their connections to contraceptive use, these factors
being grouped in the lowermost portion of Figure 1-1. The ambiguities in
these concepts are revealed perhaps more clearly in an application to sub-
Saharan Africa than they are in other settings, and we attempt to clarify the
issues as much as possible.
DEMAND FOR BIRTHS
As envisioned in the framework of Figure 1-1, the concept of demand
for births incorporates demands both for spacing births and for limiting
them. The distinction between spacing and limiting motivations is of course
very important with respect to the longer-run implications of method use.
However, apart from sterilization, use of a contraceptive method does not in
itself give evidence as to the relative weight of the spacing and limiting
motives. .
Rather, birth spacing is accommodated in the Easterlin-Crimmins syn-
thesis by the consideration of a relatively short decision period, wherein an
individual attaches utility rankings to various probabilities of conception
within the period in question. A person with-a strong motivation to delay
the next birth would assign a utility penalty to behavioral choices that entail
high probabilities of conception; so too would a person with a strong moti-
vation to avert the next birth altogether. The birth spacer may be motiv fated
by concern for child survival, the birth averter by a desire to limit family
size; but each is engaged in behavior that has a contraceptive effect. The
differences in these underlying motivations would emerge in the subsequent
sequence of decision periods, as the utility penalty associated with concep-
tion progressively declines for birth spacers while (presumably) remaining
constant for birth averters.
To put it differently, the spacing-lim~ting distinction has to do, in one
respect, with the length of the decision period to which the analytic model
is applied and, in another, with the linkages among such decision periods
over the reproductive life span. We do not propose to address here the
theoretical issues associated with birth spacing and limiting. A full treat-
ment would require an explicitly dynamic decision framework with due
allowance for uncertainty and for the interplay over the reproductive span
between reproductive outcomes and contraceptive-related choices.3 Rather,
3For exploratory work in this area, see the volume edited by Tsui and Herbertson (1989);
one article in the collection, Montgomery (1989), sets out the dynamic theory as applied to
contraceptive use.
OCR for page 224
224
FACTORS AFFECTING CONTRACEPTIVE USE
the framework of Figure 1-1 is drawn so as to give equal theoretical stand-
ing to spacing and limiting motives for contraceptive use, and to suggest
further that in sub-Saharan Africa, there need be no neat line of division
separating them.
Along with the intertemporal aspect of demand, the interpersonal aspect
must also be recognized. We argue in Chapters 3 and 4 that a reproductive
decision framework appropriate to sub-Saharan Africa must admit the pos-
sibility of separate interests on the part of the male and the female in a
reproductive pair. It follows that the concept of demand must itself be
individual specific. Thus, in assigning utility rankings to decision options
regarding method use, a woman would take into consideration her own
present and expected future resources, resources from her husband on which
she can expect to rely in the future, the possibility of future marital dissolu-
tion or the entry of new wives into the union, and so on. The husband
would have his own calculations in these matters, which would not neces-
sarily yield rankings in agreement with those of his wife.
Indeed, once the reproductive pair is split in this fashion, a gap is
introduced between individual demands and contraceptive behavior. Whose
demands and utility rankings are actually expressed in contraceptive use?
The use of certain methods, including most of the coitus-dependent meth-
ods, requires a measure of cooperation between spouses or, at minimum, an
acquiescence on the part of one spouse. Other methods can be employed
unilaterally and even surreptitiously, without requiring the knowledge of
one's spouse. In some socioeconomic circumstances where one might ex-
pect husband-wife conflicts, it might prove useful to distinguish among
contraceptive methods according to the degree of spouse cooperation they
entail.
SUPPLY OF BIRTHS
As indicated above, the supply of births that influences decisions about
contraceptive use is affected by proximate determinants that are clearly
exogenous, such as individual fecundability; those that can be treated as
exogenous only in the short run, such as spouse separation; and possibly
determinants such as breastfeeding and postpartum abstinence, whose exogeneity
is in doubt.
However, there is considerable empirical evidence that marriage, mari-
tal dissolution' spouse separation, breastfeeding, and postpartum abstinence
are correlated with the same socioeconomic factors (e.g., urbanization and
female education) that influence contraceptive use.
Moreover, in a number of African societies (Page and Lesthaeghe, 1981)
the motivation for breastfeeding and abstinence is explicitly understood in
contraceptive terms: as the traditional African means of spacing births.
OCR for page 225
APPENDIX A
225
(The spacing motive has to do with the health of the child and the mother,
but this is not the important point.) How then can these behaviors be
viewed as exogenous determinants of contraceptive use? A related question
must be raised about the appropriateness of including women who are
breastfeeding or postpartum abstinent in calculations of contraceptive prevalence.
From the analytic point of view, it would be awkward to group postpar-
tum behaviors such as breastfeeding, which is tied in a physiological sense
to a previous birth, with contraceptive methods that in principle can be
adopted at any point in the reproductive span. One simply does not take up
breastfeeding six months into a birth interval; the prevalence of breastfeeding
is therefore bound up with the incidence of births in a way that the preva-
lence of the pill or the intrauterine device (IUD) is not.
The case of postpartum sexual abstinence is less clear-cut because,
unlike breastfeeding, abstinence could well be adopted midway in a birth
interval. Here we must argue that the psychic costs associated with a given
spell of abstinence are lower if the spell begins at the event of birth, rather
than at some later point in the birth interval. This argument returns to the
African emphasis given to birth spacing and the social sanctions that sur-
round weaning and the resumption of sexual relations (Caldwell and Caldwell,
1981~. From this perspective, abstinence can be viewed as a postpartum
behavior somewhat akin to breastfeeding, although its link to the previous
birth is behavioral and social in origin rather than physiological.
The analytic awkwardness associated with treating breastfeeding and
postpartum abstinence on an equal footing with contraceptive methods con-
sists in both the interpretation and the implications of contraceptive preva-
lence rates. Consider a prevalence calculation in which the base comprises
all nonpregnant women and nonuse is distinguished from use of various
contraceptive methods. If we decide to group breastfeeding and abstinence
with other conventional contraceptive measures, we must at the same time
recognize their highly distinctive patterns of adoption and discontinuation,
and for breastfeeding, a contraceptive failure rate that is strongly dependent
on duration.4
To be correctly interpreted, contraceptive prevalence rates that incorpo-
rate breastfeeding and abstinence would have to be calculated by holding
constant the duration since last birth. Consider a comparison of distribu
4It has been hypothesized that the contraceptive effect of breastfeeding could be maintained
indefinitely if feeding were to be sustained at maximum intensity. But the usual pattern is for
breastfeeding to decline in intensity as food supplements are introduced into the infant's diet,
and this process may be accelerated by the physiological strain or fatigue on the part of the
mother associated with long durations of full breastfeeding. Hence, it is safe to assume that
the use-effectiveness of breastfeeding, as it were, will tend to erode with duration since last
birth.
OCR for page 226
226
FACTORS AFFECTING CONTRACEPTIVE USE
lions of nonuse and use by method among nonpregnant women at two dura-
tions, d and d + 1, since last birth. In moving from duration d to duration
d ~ 1, one would expect to see a systematic reduction in the percentage
breastfeeding and postpartum abstinent, and a systematic inflation in the
sum of nonuse and use of conventional methods. One would then have to
devise corrections to the prevalence rates that would net out such system-
atic patterns, in order for more interesting behavioral regularities to be
discerned in the data.
Moreover, owing to the systematic decline in the contraceptive failure
rate of breastfeeding with duration since birth, the greater the duration d is,
the larger is the fraction of women breastfeeding and not pregnant at d who
then conceive and are removed from consideration at duration d + 1. So
far, as we are aware, no other conventional means of contraception displays
such a pronounced duration dependence in its failure rate. When contracep-
tive methods are defined so as to include breastfeeding therefore, the impli-
cations of a given method mix for the degree of contraceptive protection
will depend on the duration since last birth.
The second part of the rationale for treating breastfeeding and postpar-
tum abstinence differently from contraceptive use has to do with the contri-
bution to understanding and to policy of statistical analyses based on a
synthesis framework. The concern is a general one, perhaps most readily
evident here in respect to postpartum behaviors, but also of relevance in
marriage, spouse separation, and other choice-related behavior having an
influence on the risks of conception. The issue can be framed in the follow-
ing way: In what sense, if any, will analyses of contraceptive use defined
as conditional on the status of other proximate determinants, tend to mis-
lead?
The central issue is that of statistical erogeneity, selectivity bias, and
the importance of unmeasured variables.5 Perhaps a simple representation
SEconomic demographers have given great emphasis to the concept of statistical erogeneity,
as is evident in Schultz's (1986) critique of the Easterlin synthesis. It should be recognized
that the key issue is in fact of a statistical nature, rather than being an issue of the appropriate
theory.
The concept of conditional demand functions, wherein the demand for one good is ex-
pressed as being conditional on demands for other goods, is well accepted in economic theory.
The analogy here would be to the demand for contraception conditional on breastfeeding status
or conditional on the status of other proximate determinants. But economists have also recog-
nized the difficulties in statistical applications of conditional demand theory, given that the
theoretically appropriate conditional demand functions will typically include a number of vari-
ables that are not subject to empirical measurement. Thus, an empirical application of condi-
tional demands will be vulnerable to the charge of selectivity bias arising from omitted vari-
ables.
This contrast in perspectives is evident in the exchange between Easterlin (1986) and
OCR for page 227
APPENDIX A
227
of method use and postpartum abstinence can help to illuminate. Let C
denote the use of a contraceptive method by individual ~ and let Ai indicate
postpartum abstinence on the part of this individual. A set of variables Xi
encompasses all measurable exogenous socioeconomic determinants of con-
traceptive use, including program-related measures of contraceptive access
and costs. In any empirical application, important components of the deter-
m~nants of use will doubtless go unmeasured, and these unobserved influ-
ences are summarized in the variable £i, the value of which will vary across
individuals. We assume that Xi and £i are unco~Telated.6
If both contraceptive use, Ci, and postpartum abstinence, Al, are viewed
as endogenous, a linear statistical representations of the determinants of C.
and Ai could be set out as follows:
Ci = Xi Dc + ci + Vi
Ai = XipA + a Pi +Ui'
r
where the unmeasured background factors si exert an influence on both
method use and postpartum abstinence. (We accommodate any additional
unmeasured influences on abstinence in the disturbance terms vi and ui,
which can be taken to be uncorrelated with £i.) Because Xi and (si and vi)
are uncorrelated, we have
EtCilXi ~ = Xi Dc'
and the coefficients pc of the contraceptive use equation can be consistently
estimated by conventional methods.
Consider now the alternative approach in which the equation for contra-
ceptive use Cz is estimated as conditional on abstinence status Ai. For
instance, the contraceptive use equation could be estimated on the subsample
of women who are not postpartum abstinent, which we may represent as A
= 0. Then in the subsample,
Schultz (1986) concerning empirical applications of the synthesis model. Easterlin defends his
empirical specification of the model in terms of conditional demand theory (although he does
not use this language), whereas Schultz attacks the specification primarily on statistical grounds.
6That is, Xi is exogenous from the statistical point of view.
7We use a linear regression representation only to illustrate the key issues; clearly it is not
the most appropriate framework for qualitative variables such as contraceptive method choice.
OCR for page 228
228 FACTORS AFFECTING CONT~CEPTIVE USE
EtCilXi' Ai = 0] = Xi'pC + Er£ilAi = 0]
= Xi TIC + Et£~1£i = ~-11a)(Xi PA + Ur)]
~ X'0
In short, when a common unmeasured variable Pi enters both the contracep-
tion and the abstinence equations, the influence of socioeconomic and pro-
gram determinants of demand Xi cannot be consistently determined in gen-
eral through the conditional approach. The degree of bias inherent in this
approach is an empirical matter, and it would be very difficult to know, a
priori, whether the bias would be small enough to ignore for policy or other
purposes.
The conditional approach can be defended in two ways. First, one
could argue that £i does not in fact appear in the abstinence equation (i.e.,
a = 0), which amounts to an assertion that unobserved characteristics af-
fecting abstinence do not have any influence on method use a strong as-
sertion indeed given the documented associations between the observed
socioeconomic factors Xi and abstinence. Second, one could assert that
when the data are grouped according to specific socioeconomic or cultural
criteria, so little individual-specific variation remains in Pi that it is, in
effect, absorbed into the constant terms of the regression equations, which
is the essence of the argument that proceeds from the assertion that postpar-
tum abstinence and breastfeeding are "culturally determined," to the con-
clusion that one can examine contraceptive use on a conditional basis.8
We wish to underscore this point: To justify using the conditional
approach, one or the other of these arguments must be applied to each of the
other proximate determinants, including marital status and spouse separa-
tion.
These analytic and statistical complications surrounding the synthesis
framework are not beyond resolution, but to address the issues in full in this
report would carry us into new and possibly controversial terrain with re-
gard to' methodology. In addition, we believe that the payoff in terms of
lessons for policy could be small. For both physiological and behavioral
reasons, breastfeeding and postpartum abstinence are necessarily limited
behaviors. No conceivable policy could hope to extend the duration of
breastfeeding or abstinence much beyond three years, and even reaching
three years would be doubtful in the case of abstinence, whereas policies in
sub-Saharan Africa could well encourage durations of modern contraceptive
The group-specific nature of Pi wounds then be captured in dummy variables indicating
region, ethnicity, and the like.
OCR for page 229
APPENDIX A
229
use of this length or longer. With regard to the other proximate determi-
nants such as marital status, it seems unlikely that program interventions
directed to contraceptive use could have important spillover influences on
selection into marriage.
To sum up, our approach in this volume proceeds as follows: Our
judgment is that marital status is probably not sufficiently endogenous to
cause concern. Thus, we calculate measures of contraceptive prevalence for
currently married women. Breastfeeding and abstinence are treated as po-
tentially endogenous; we do not calculate contraceptive prevalence mea-
sures conditional on breastfeeding and abstinence status. But neither do we
merge breastfeeding and abstinence with other contraceptive methods. Our
attention is restricted to modern method use.
This focus on a subset of the endogenous variables may well be ad-
equate for an exploration of contraceptive use, but given the possibilities
for substitution between breastfeeding/abstinence and modern contraceptive
methods, it could yield misleading predictions about fertility. This issue is
discussed in Chapters 2 and 7 in connection with the two-phased fertility
transition in Africa.
Representative terms from entire chapter:
proximate determinants
