# st: RE: RE: RE: creating age at first birth from birth history data

 From "Nick Cox" To Subject st: RE: RE: RE: creating age at first birth from birth history data Date Mon, 26 Apr 2004 17:20:32 +0100

```I am not clear on what is problematic to you here, but
one simple thing may bite you sooner or later.

Your -year- variable takes on values 0 ... 3
and 60 ... 99 meaning presumably 2000 ... 2003
and 1960 ... 1999.

Fix that straight away by

gen Year = cond(year < 4, 2000 + year, 1900 + year)

I'm suggesting a new variable, so that you can
check -Year- against -year-.

Nick
n.j.cox@durham.ac.uk

> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Henry DOCTOR
> Sent: 26 April 2004 16:42
> To: 'statalist@hsphsun2.harvard.edu'
> Subject: st: RE: RE: creating age at first birth from birth
> history data
>
>
> I just want to be more clear with the data that I have again:
>
> I have the following variables:
>
> Age of mother, all pregnancies the mother has had (starts
> with last born and
> ends with first born), birthday for each child, an indicator
> variable for
> the child number which runs from 0 to the last child. So, I
> want the reverse
> order for the list of children (first born to last born).
>
> There are a total of roughly 16,000 pregnancies for the women
> and I tried
> what Nick suggested but I am just wondering why I am getting
> the same number
> of pregnancies (16,000). I thought the first births would be
> less than the
> 16,000.
>
> This is how my data are:
>
> tab child_n if child_n!=88  (In this case child 1 is last
> born, child 2 is
> second to last born etc etc)
>
>       child |
>      number |      Freq.     Percent        Cum.
> ------------+-----------------------------------
>           1 |      4,105       24.71       24.71
>           2 |      3,452       20.78       45.49
>           3 |      2,899       17.45       62.93
>           4 |      2,345       14.11       77.05
>           5 |      1,628        9.80       86.85
>           6 |      1,090        6.56       93.41
>           7 |        607        3.65       97.06
>           8 |        309        1.86       98.92
>           9 |        104        0.63       99.55
>          10 |         47        0.28       99.83
>          11 |         17        0.10       99.93
>          12 |          9        0.05       99.99
>          13 |          2        0.01      100.00
> ------------+-----------------------------------
>       Total |     16,614      100.00
>
> tab year (year child was born)
>
>  year child |
>        born |      Freq.     Percent        Cum.
> ------------+-----------------------------------
>           0 |        717        4.23        4.23
>           1 |        657        3.88        8.11
>           2 |        653        3.85       11.96
>           3 |        570        3.36       15.32
>          60 |          2        0.01       15.33
>          61 |          1        0.01       15.34
>          62 |          1        0.01       15.34
>          63 |          2        0.01       15.36
>          64 |          1        0.01       15.36
>          65 |          1        0.01       15.37
>          66 |          2        0.01       15.38
>          67 |          5        0.03       15.41
>          68 |          9        0.05       15.46
>          69 |         14        0.08       15.54
>          70 |         45        0.27       15.81
>          71 |         35        0.21       16.02
>          72 |         74        0.44       16.45
>          73 |        112        0.66       17.11
>          74 |        109        0.64       17.76
>          75 |        151        0.89       18.65
>          76 |        174        1.03       19.67
>          77 |        207        1.22       20.90
>          78 |        256        1.51       22.41
>          79 |        253        1.49       23.90
>          80 |        399        2.35       26.25
>          81 |        348        2.05       28.31
>          82 |        347        2.05       30.35
>          83 |        481        2.84       33.19
>          84 |        509        3.00       36.19
>          85 |        487        2.87       39.07
>          86 |        526        3.10       42.17
>          87 |        583        3.44       45.61
>          88 |      1,806       10.65       56.26
>          89 |        525        3.10       59.36
>          90 |        722        4.26       63.62
>          91 |        608        3.59       67.21
>          92 |        610        3.60       70.80
>          93 |        682        4.02       74.83
>          94 |        693        4.09       78.92
>          95 |        700        4.13       83.05
>          96 |        711        4.19       87.24
>          97 |        724        4.27       91.51
>          98 |        638        3.76       95.27
>          99 |        801        4.73      100.00
> ------------+-----------------------------------
>       Total |     16,951      100.00
>

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