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From |
"Sidney Atwood" <SATWOOD@hsphmail.harvard.edu> |

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

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

Date |
Wed, 28 Apr 2004 12:37:27 -0400 |

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/

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