obvious choice, as spouses generally live together and could therefore be expected to report reliably on symptomatology. In Senegal, for example, spouses and parents were able to provide information leading to a diagnosis in 41% of cases, compared to 19% for other respondents (Garenne and Fontaine, 1986). There are, however, some disadvantages in questioning solely about spouses. In some societies, the definition of "spouse" is not always clear, especially in urban areas in which informal unions are common. Where divorce or separation are common, there may be confusion as to which spouse is intended, and respondents may be unable to report on the symptoms surrounding the death of a former spouse. Moreover, in the case of female deaths, the main carer in some societies tends to be a daughter or sister rather than the husband. Certainly it has been suggested in the context of studies of maternal mortality that sisters are better respondents than husbands (Graham et al, 1988). Finally, deaths of single adults would be missed completely.

It may be preferable, therefore, to question respondents about the survival of all their close relatives. This could include spouses, siblings, children that have reached adult age, and parents.

Further questioning, about the symptoms associated with a death, would be restricted according to the time of death (see Section 3.2.3), and the proximity of residence of the respondent and the deceased. Criteria for proximity would clearly include those who were living in the same household at the time of death. It is less clear whether respondents living in the same village or neighbourhood as the deceased would be acceptable, and this point requires further research.

# 3.2.3 Recall period

Given that adult deaths are relatively rare events, the use of a long recall period would be of benefit in reducing sample size. However, detailed information about the illness preceding death is unlikely to be recalled over a long period of time. The optimal recall period for surveys of cause-specific mortality must therefore be considered.

Most reported work on retrospective cause-of-death enquiries ("verbal autopsies") has been carried out in studies of deaths in childhood. They have usually involved questioning the mothers of dead children, or some other relative if the mother was unavailable. In Senegal, Garenne and Fontaine (1986) found that both the response rate, and the percentage of deaths for which cause was specified, were greatest when the interval between the death and the interview was between three and eight months. Zimicki (1989) in Bangladesh found that intervals of up to ten months did not affect the amount or quality of information obtained, and suggested that, as distress may be caused by asking about a death soon after its occurrence, it may be preferable to wait several months. Bradley and Gilles (1984) conducted interviews within one month of the death, and Greenwood et al (1987) used intervals of up to three months. The latter felt that information obtained more than three months after death would be unreliable.

It generally seems to be accepted, therefore, that recall periods exceeding one year are inadvinable for child deaths. It is possible 14