Analyzing birth intervals: Implications for demographic theory and data collection

In the last decade, the study of birth intervals has been greatly facilitated by a rapid expansion in data availability and by improvements in analytical techniques. Unfortunately, the results emerging from individual level, empirical studies of birth interval dynamics do not correspond with the predictions of standard demographic theory. This paper reviews a series of individual level studies that find substantial socioeconomic variation in childspacing after controlling statistically for the major intermediate or proximate variables. It then offers possible explanations for the lack of fit between theory and results at the micro level, concluding that the two most likely explanations are poor measurement of the four principal proximate determinants and the exclusion of additional proximate determinants.     

Interpersonal communication and the diffusion of family planning in West Malaysia

Using data from a 1966–1967 probability sample of West Malaysian married women 15–44 years of age, this paper analyzes the characteristics of women who were active in diffusing information about family planning. The woman’s age and her parity, her educational attainment, her race, her present residence (urban-rural), and whether or not she wanted more children were significantly related to opinion leadership in bivariate tables. However, these relationships appeared to be substantial mainly because these social and demographic characteristics were highly related to whether the woman participated in discussions about family planning with other women. Among women who did participate in such discussions, the social and demographic variables were not substantially related to opinion leadership. In fact, the critical variables for opinion leadership appeared to be participation in the discussions, greater knowledge of family planning, and a higher level of family planning use. An attempt is also made to assess the effect of interpersonal communication on the adoption of family planning among women in the sample.     

Explaining regional fertility variations in the Philippines

Analysis of the 1993 National Demographic Survey in the Philippines has uncovered regional variations in fertility-related behavior. The total fertility rate ranged from 2.8 in Manila to 5.9 in Bicol and averaged 4.1 for the entire country, but contraceptive prevalence rates were not highly correlated with total fertility (Manila showed the fifth highest prevalence, and Bicol the fifth lowest). This lack of correlation may be caused by the mix of contraceptive methods chosen with a high proportion of women using ineffective methods (40% of all currently married women of reproductive age [MWRA] were using contraceptives, but only 25% were using the most effective methods). Thus, low fertility was associated with use of the most effective methods regionally. Fertility also was lower in regions where women spent more time unmarried. Infecundity added to the discrepancy (Bicol had the lowest regional infecundity rate in the country). The total protection rate, which can be derived from three factors (contraceptive usage, time spent unmarried, and infecundity), accounts for must of the regional variation. Unmet need for contraception was found in 26% of currently MWRA, and another 12% were using ineffective methods. In designing effective family planning programs, policy-makers must understand the various factors that contribute to high levels of fertility in different regions and must be flexible enough to plan regionally-specific strategies. As the government decentralizes programs and resource management decisions, local-level analysis will be increasingly important.     

Self-Reported Ageism in Social Work Practitioners and Students

In this study, we focus on self-reported ageism in college students and social service providers using the Relating to Older People Evaluation (ROPE; Cherry & Palmore, 2008 Cherry, K. E. and Palmore, E. B. 2008. Relating to Older People Evaluation (ROPE): A measure of self–reported ageism. Educational Gerontology, 34: 849–861. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). The ROPE is a 20-item questionnaire that measures positive and negative ageist behaviors that people engage in during everyday life. Participants included undergraduate and graduate social work students and practicing social service providers in the nursing home and mental health setting. Findings indicate that people of varying educational backgrounds and occupational experience in social services readily admit to positive ageist behaviors. Item analyses revealed similarities and differences between groups in the most and least frequent forms of ageism endorsed. Ageism as a social phenomenon with implications related to social work policy and practice is discussed.     

Marriage Patterns And Cumulative Fertility In West Malaysia: 1966–1967

Differentials in age at first marriage and being married more than once are discussed for a probability sample of West Malaysian currently married women 15-44 years of age. Both marriage ages and the incidence of multiple marriages vary greatly by race, place of current residence, wife's education, and husband's occupation; and the marriage variables are shown to have significant effects on the cumulative fertility of West Malaysian women. Early marriage leads to higher cumulative fertility and multiple marriages lead to lower cumulative fertility. Since the social groups with the highest proportions of early marriages are also those with the highest incidence of multiple marriages, the marriage variables explain some but not all of the variance in cumulative fertility for West Malaysian social groups. After adjustment for the effects of the marriage variables, rural Indian or Pakistani women still have the highest cumulative fertility and urban Chinese women with more than five years of schooling still have the lowest cumulative fertility.     

Intermediate variables and educational differentials in fertility in Korea and the Philippines

This analysis compares the effects of contraceptive use and infant and fetal mortality on the pace offertility in Korea and the Philippines and explores the mediating effects of these intermediate variables on educational differentials in childspacing. For birth intervals initiated in a recent period before a sample survey, second, third and higher-order intervals are examined. Transitions within successive segments of interval exposure (q _xvalues) are examined rather than cumulative transitions (1 - l _xvalues). This methodological choice is substantively important because breastfeeding should primarily affect early segments of exposure and because it allows empirical examination of the timing of the effects of other variables such as contraceptive use. Further, this choice allows multivariate analysis within the structure of the life-table perspective. The results show substantial differences in patterns between Korea and the Philippines, indicate clearly the effect of each intermediate variable, and illustrate how educational differentials in fertility are affected by contraception and infant and fetal mortality.     

Analyzing fertility histories: Do restrictions bias results?

The straightforward tests we have conducted lead to two major conclusions. First, parameter estimates, such as the proportions that practice contraception or that breastfeed, can be biased in data restricted to the last closed and open interval. This is particularly true the further back in time one goes. However, the second conclusion is that these restrictions do not bias estimates of the structure of the relationships predicting fertility. This may seem surprising, and perhaps even magical. The reason is that multivariate life table techniques allow one to reach the same conclusion even if the proportions in various categories are altered by a criterion such as limiting the analysis to intervals begun by the last and next-to-last live births. Limiting the analysis in this way means that there are fewer short intervals and thus fewer cases of intervals with characteristics associated with short intervals (e.g., no contraceptive use, no breastfeeding, or infant mortality). As long as the model specified in the multivariate life table is an appropriate one, that is, it is not misspecified, and as long as the skew produced by the WFS restriction is not too extreme, then the multivariate life table procedures can produce unbiased estimates of the structure of the relationships predicting birth interval dynamics. Thus even though the WFS data are in fact inappropriate for some simple parameter estimation procedures, they appear to be adequate for the more complex multivariate procedures of the sort used here. Several caveats must be added to the foregoing results. First, we have performed this test in only one country, Korea; it is possible that the same results might not be obtained in other countries. We expect, however, that they would. Second, our procedure only looks at the first 40 months of experience in the birth interval. A procedure that incorporates the long tails of the birth interval distribution may obtain different results. In fact, we caution against analyzing the tail of the distributions using data from the normal WFS sample, since these would be most affected by the restriction to last closed and open intervals. Third, the extent to which these results are generalizable to other types of substantive problems is unknown at present. We suspect, however, that examining the determinants of lengths of breastfeeding will produce similar results. Finally, even with multivariate procedures, it would be highly misleading to impose the WFS restrictions and then examine trends in the length of birth intervals.(ABSTRACT TRUNCATED AT 400 WORDS)