Chuuk State Census Report - pacificweb.org

2000 FSM Census of Chuuk StateChapter 4. FertilityTable 4.3: Registered Births by Calendar Year and Implied Crude Birth Rate, Chuuk State: 1992 to 1999Index 1992 1993 1994 1995 1996 1997 1998 1999Registered births 1,108 1,157 1,139 1,094 1,044 1,101 1,160 1,138Implied crude birth rate (CBR) 21.8 22.3 21.6 20.5 19.6 20.6 21.7 21.3Source: Department of Health Services, FSM, unpublished dataAs long as the assumptions made in choosing the life table and in selecting a rate of growth are reasonable, the errors infertility estimates, resulting from the lack of better data, will be small. The principal merits of the CBR as a measureof fertility are its relative simplicity and its interpretation as a direct contribution to the rate of natural growth.However, the CBR in relation to the total population tells little about the fertility of women neither at reproductive agesnor about the age structure of childbearing. We must be very careful in using CBR for comparison. The CBRestimates are dependent on the age structure of a population. As a result, unless standardized, they will not becomparable over time or across regions with different age structures. Fortunately, the census data do enable us tomeasure fertility in more detail.Age-Specific FertilityTo look at the recent age structure of births, the age groups of mothers can classify children born in the past year. Thistabulation enables the calculation of age specific fertility rates (ASFR), that is, the average number of children born toeach woman in an age group during the year. Relating fertility experience to age provides a more detailed descriptionof fertility behavior or family formation, and provides a control of changes in age structure for comparative purposes.This report provides two methods for calculating and adjusting ASFRs. One involves reverse survival of births and theother involves comparing current fertility to previous fertility to check for under counting. The reverse survival methodis discussed first.Before producing age specific rates through reverse survival, the number of births in the past year reported by womenwas adjusted (see Table 4.1). This type of question is often under-reported and considerable care is needed for theresults to be usable. Consider, for example, the 1,471 estimated births for the year 1999-2000 based on reverse survivaland shown in Table 4.1. Assuming that the effects of migration for infants below one year were moderate anddiscrepancies arising from multiple births and maternal deaths were negligible, the response to the question elicitinginformation on births in the past year should be the same, or at least very close. As Table 4.4 shows, the total numberof women reporting a birth in the past year was 1,393, considerably lower than the estimated 1,471 derived from usingreverse survival.In order to correct for the under count, an adjustment factor is calculated by dividing the estimated births from reversesurvival by the reported number of births. In this case, it would be 1,637 estimated births divided by 1,393 reportedbirths resulting in an adjustment factor of 1.06 (see Table 4.4). The adjustment factor is then applied to the births tocorrect for the under count.Table 4.4: Adjustment of Births in Year Prior to the Census, Chuuk State: 1994 and 20001994 2000Number Reported Unadjusted Adjusted Adjusted Number Reported Unadjusted Adjusted AdjustedAge groups of women births ASFR births ASFR of women births ASFR births ASFRTotal 11,852 1,417 ... 1,689 ... 13,061 1,393 ... 1,471 ...15 to 19 years 2,855 75 0.026 89 0.031 3,343 93 0.028 98 0.02920 to 24 years 2,214 280 0.126 334 0.151 2,270 316 0.139 334 0.14725 to 29 years 1,708 332 0.194 396 0.232 2,032 380 0.187 401 0.19730 to 34 years 1,605 325 0.202 387 0.241 1,571 288 0.183 304 0.19435 to 39 years 1,426 228 0.160 272 0.191 1,451 199 0.137 210 0.14540 to 44 years 1,197 143 0.119 170 0.142 1,293 91 0.070 96 0.07445 to 49 years 847 34 0.040 41 0.048 1,101 26 0.024 27 0.025TFR ... ... 4.35 ... 5.18 … … 3.84 … 4.06Source: 1994 FSM Census, Table P15; 2000 FSM Census, Table P2-3.Note: Adjustment factor equals total births (reverse survival) divided by the number of women reporting a birth in the past year.Chuuk Branch Statistics Office, Division of Statistics, FSM Department of Economic Affairs 37