Part II Data and Methods
14.3 Fertility and Family Survey
1.Even if surveys refer to the same region and historical period they are likely to provide more or less different data. So it is always a good idea to consider all possibly informative data sources and compare the infor-mation. In the present section we use data from the German part of the Fertility and Family Survey (FFS). The FFS project was initiated by the Population Activities Unit (PAU) of the United Nations Economic Commission for Europe (UNECE) in order to conduct comparable Fertility and Family Surveys in about 20 ECEmember countries.13 The German FFS was conducted by theBundesinstitut f¨ur Bev¨olkerungsforschung(BiB, Wiesbaden) in 1992.14 While several studies using these data have already been performed and published,15 the data set is now generally available for scientific research.16
2.The sampling design intended to get data from 10000 persons, 5000 in the territory of the formerFRG(“West”) and 5000 in the territory of the formerGDR(“East”). In both territories, 3000 women and 2000 men of age 20 to 39, having a German citizenship, should be included.17 The field work was done during the period May to September in 1992 using a random route method to select persons for the survey. The final sample includes data from interviews with 10012 persons. The number of male and female sample members in both regions of Germany is shown in the left part of the following table:
All sample members With valid birth year
Region Male Female Male Female
West 2024 3012 2016 3005
East 1992 2984 1982 2971
Since for 38 persons neither a valid birth year nor a valid age at the time of the interview is known, the number of cases reduces as shown in the right part of the table. All remaining persons are born between 1952 and
13Seewww.unece.org/ead/pau/ffs/. Festy and Prioux (2002) provide an overview and evaluation.
14The basic data documentation is by Pohl (1995). For additional information see the homepage of the BiB:www.bib-demographie.de.
15Hullen (1998), Roloff and Dorbritz (1999).
16We thank Gert Hullen (BiB) who provided us with a copy of the data. The data set is also available from theZentralarchiv f¨ur empirische Sozialforschung (K¨oln).
17For more details on the sampling design see Pohl (1995, pp. 7-8).
Table 14.3-1 Age at first childbearing in the FFS subsample.
West East
C55 C60 C65 C55 C60 C65
τ d= 1 d= 0 d= 1 d= 0 d= 1 d= 0 d= 1 d= 0 d= 1 d= 0 d= 1 d= 0
15 1 2 3 1 1
16 6 5 3 3 6 5
17 12 6 4 7 14 9
18 32 13 13 35 36 23
19 28 22 13 59 69 57
20 49 21 28 67 106 88
21 38 32 25 94 108 95
22 30 35 19 94 90 91
23 34 31 53 68 62 76
24 40 39 23 54 52 49
25 39 50 32 141 42 48 30 52
26 36 32 26 103 25 33 30 45
27 30 47 17 101 17 17 5 42
28 30 39 8 96 11 15 6 19
29 28 33 2 59 13 6 26
30 33 14 91 7 8 26
31 20 9 46 7 3 24
32 13 4 67 4 2 15
33 12 1 42 5 9
34 6 41 2 17
35 8 47 2 19
36 3 37 2 10
37 35 11
38 1 34 12
39 46 30
Total 529 199 435 287 266 500 621 82 676 91 565 184
1972. Since our interest concerns births we only consider female sample members. In order to allow comparisons with the GLHS and SOEP we only consider women who belong to one of the birth cohorts shown in the following table:
Birth cohort Birth years West East
C55 1953−57 728 704
C60 1958−62 723 767
C65 1963−67 768 751
3.As was done in the previous sections, we begin with an investigation of the distribution of ages at first childbearing. Table 14.3-1, organized in the same way as Tables 14.1-1 and 14.2-1, shows the data and can be used to calculate survivor functions.18 For the cohorts C55 (West) and
18Like the GLHS, also the FFS allows to distinguish women’s own children from step children and adoptive children. For creating the data in Table 14.3-1 we have only
15 20 25 30 35 40 45
0 0.5 1
SOEP FFS
C55 (West)
15 20 25 30 35 40 45
0 0.5 1
GLHS FFS
C60 (West)
Fig. 14.3-1 Comparison of survivor functions for the age at first child-bearing. FFS survivor functions are calculated from the data in Table 14.3-1. The SOEP and GLHS survivor functions are taken from Figures 14.1-1 and 14.2-1, respectively.
C60 (West) they can be compared with corresponding survivor functions from the SOEPand GLHS respectively. As can be seen in Figure 14.3-1, the curves agree quite well. So we can turn to a comparison of all six age distributions that can be calculated with the data in Table 14.3-1.
The result is shown in Figure 14.3-2. Quite remarkable is the difference between the distributions in both territories. In the formerGDR, women began childbearing at substantially younger ages, and also the proportion
considered women’s own children. One should note, however, that in a few cases no valid birth year for the first child is available, the number of women referred to in Table 14.3-1 is therefore slightly smaller than in the table in paragraph 2.
15 20 25 30 35 40 45 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
C55 (West) C60 (West)
C65 (West)
C55 (East) C60 (East)
C65 (East)
Fig. 14.3-2 Distribution of age at first childbearing described by survivor functions, calculated from the data in Table 14.3-2.
Table 14.3-2 Number of children in the FFS subsample, classified with respect to mother’s birth cohort and age (τ).
West East
τ C55 C60 C65 C55 C60 C65
15 1 2 3 1 1
16 7 5 4 4 7 5
17 12 6 6 8 14 10
18 36 17 13 37 39 26
19 31 23 13 62 75 61
20 61 27 38 79 119 100
21 50 42 29 113 143 114
22 51 58 31 128 142 138
23 49 55 69 116 127 118
24 70 60 48 105 112 108
25 71 75 60 113 111 69
26 62 62 47 86 110 71
27 61 85 32 74 81 30
28 64 84 13 53 63 13
29 62 70 9 41 36 1
30 69 56 47 29
31 52 38 28 19
32 40 17 26 8
33 38 13 23 3
34 26 2 8 1
35 25 8
36 11 6
37 1 5
38 4 1
39 1
Total 955 797 412 1174 1240 865
Total∗ 981 826 429 1213 1253 887
of childless women was much smaller than in the former FRG. Further-more, the distribution is quite similar for all three cohorts. In contrast, the tendency of delaying childbearing into older ages continues in the western part of Germany. Of course, at least for the birth cohorts C60 and C65, the data to not allow to reliably estimate the proportion of eventually childless women.
4.We now turn to the number of children and begin with cumulated cohort birth rates. The data are shown in Table 14.3-2. As in Table 14.3-1, we have only considered women’s own children. We also note that the FFS questionnaire only asked for birth years of up to four children. However, the number of women with more than four children is quite small (seven women have five, and four women have six children). More important is the number of cases where, for one or more children, there is no valid birth year. This is documented in the last two rows of Table 14.3-2. The row labeled Total∗ has been calculated from women’s report on the total number of their own children, so that the difference between both rows
1970 1980 1990 2000 0
0.5