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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: RE: RE: creating age at first birth from birth historydata |

Date |
Wed, 28 Apr 2004 17:53:42 +0100 |

In the original 88 was used as a code for missing -child_n-. As this is evidently larger than what is possible in practice, the effect of this code would be to sort all the 88s to low _n, and thus contaminate what is kept to the maximum degree. If in fact numeric missing were used, the same would not apply, which I think is what Sidney has in mind. Nick n.j.cox@durham.ac.uk Sidney Atwood > I like the bysort but we need to take the highest numbered kid and > perhaps that birthdate is missing. Try this: > How about > > gsort momid -child_ n > by momid:keep if _n==1 > > This will produce a dataset with one observation per mother - > her first > born child. Merged back into your mother's dataset will then allow you > to get mother's age at first birth. > > ssa > > > > /*********************************** > Sidney Atwood > Manager > Instructional Computing Facility > Harvard School of Public Health > Kresge, LL-17 > 677 Huntington Avenue > Boston, MA 02115 > 617-432-3134 > 617-432-4998 - Fax > ************************************/ > > >>> HDOCTOR@navrongo.mimcom.net 4/26/2004 11:41:37 AM >>> > 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 > > I hope this helps > Henry > > ******************************************************** > Henry V. Doctor > Navrongo Health Research Centre > P.O. Box 114 > Navrongo, Upper East Region > GHANA > tel/fax: +233 (0)742 22320; cell: +233(0)244 433706 > ******************************************************** > > > -----Original Message----- > From: Nick Cox [mailto:n.j.cox@durham.ac.uk] > Sent: 26 April 2004 10:57 > To: statalist@hsphsun2.harvard.edu > Subject: st: RE: creating age at first birth from birth history data > > I'll guess at your data structure. If this > isn't correct, you may need to say more > about it. > > I assume some identifier variable > and a variable containing dates of birth > of children, as in > > mother birthdate > 1 1feb2001 > 1 1mar1999 > 1 4jul1996 > 1 28feb1994 > 2 2nov2003 > 2 etc. > 3 > 3 > 3 > 3 > > I also assume -birthdate- is a Stata > elapsed date. > > Your problem at its simplest is that > the birthdates are in the reverse order > fom what you want. > > bysort mother (birthdate) : gen first = birthdate[1] > > will generate a variable with firstbirths from > these data. The same value of -first- will be > repeated for each -mother-. To get the age > of the mother at the first birth, you may > need to subtract the mother's date of birth, > possily in another variable. > > Nick > n.j.cox@durham.ac.uk > > Henry DOCTOR > > > I need to create a variable called "age at first birth" > > for women from birth history data. The variable has information > > for births beginning with the last child (most recent birth) > > to the first child (first pregnancy). So, every woman has n > > children and the last (nth child) in the data is the first born. > > I want to reverse this so that the variable gives me the nth > > child for every woman as the first born. > > > * > * For searches and help try: > * http://www.stata.com/support/faqs/res/findit.html > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * > * For searches and help try: > * http://www.stata.com/support/faqs/res/findit.html > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * > * For searches and help try: > * http://www.stata.com/support/faqs/res/findit.html > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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