DIVORCE EFFECTS'AND CAUSALITY IN THE SOCIAL SCIENCES 35 the change in some outcome from before to after 3 Pre-separation predictors of post-separations divorce among the children of divorcing couples outcomes are controlled for,including espe- with change over an equivalent period among the cially any that are joint predictors of separation children of stable marriages.To avoid bias,the pre- and outcome;such predictors can be classified as divorce observation should be made prior to )specific to the child-i.e.child characteristics divorce,and this may be essential in any case because and (specific to the parents or family; some phenomena can only be observed concur- 4.To avoid bias,these predictors are measured rently.The timing of the post-divorce measurement before separation. should be unambiguous -it should relate to the Pre-separation child characteristics are of impor- period after divorce.To approximate to random-tance in general,but particularly in relation to ization,this comparison must be net of any pre-educational outcomes,since it is known that early divorce factors that influence either or both divorce ability and achievement are related to later school propensity and(the risk of)the outcome of interest.achievement and continuation rates.Condition(2) Again,observations on these covariates should be rules out studies in which initial observation of taken before any divorce occurs. children in intact families is at,say,age 12,a second In longitudinal research on children,some out- observation is at age 18,parental divorce is identified comes lend themselves to a formulation in terms of as having occurred some time between 12 and 18, change and others do not.For example,before-and-and the outcome is whether the child had ever after measures can be obtained of school attainment experienced some event-e.g.leaving school- or of emotional adjustment and a measure of change between 12 and 18.In such cases the difficulty is constructed.But others do not fit this mould.Some that the outcome might have preceded separation. behaviours and experiences become possible with These may appear to be stringent conditions though the passage of personal time that were either impos-in fact they should strictly be a great deal more so.A sible or exceedingly rare at an earlier age.Examples full set of conditions would specify that we know the include first sexual experience,first pregnancy, causes of divorce and that measures of these are cohabitation,and so on.Excepting abnormal cir- entered into the equations.There is one further pro- cumstances,such experiences occur only after mising approach via sibling studies that will be sexual maturation.In these cases,the true question considered presently. of interest is whether the rise of an early first preg- nancy etc.is raised by parental divorce beyond what it would otherwise have been.As things The Evidence stand,this risk is unobservable at the individual level.Furthermore,comprehensive predictors of The literature on the subject is in three broad future risk are,as yet,unavailable and may never be groups,although there is some overlap between known.The best we can do,within current metho-them: dological resources,is to make the comparison 1.studies reported in psychology sources,usually controlling in some way for pre-divorce characteris- but not exclusively based on small samples; tics and circumstances that are predictive of the later 2.reports in psychiatric publications,also usually behaviours. small in scale;and In sum,minimal requirements for establishing a 3.studies by demographers and sociologists,pri- link between parental divorce and later outcomes marily analyses of large data-sets. for children,whether positive or negative,that The paper addresses chiefly studies of the third kind would be a candidate for causal investigation are while drawing also on the clinical literature. these: Investigations of the first type,discussed briefly 1.Where possible,a change variable is used,with here,are numerous and in the main weak in meth- measurements taken both before and after the odology.A much cited meta-analysis by Amato and event; Keith (1991)summarized 92 such studies,that are 2 If not,that outcomes relate unambiguously to probably a fair sample of the psychological literature the period after the separation takes place; on 'divorce effects.The methodology of 84 of the 92                                 5                                    5              >           5     0               B           #  " *       +          "      !                          F                   /             7                                                                      !                !                        +     "        F         "          "  5               "                           . !           "                                  A % ? 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