Tracking Family Structure in ALSPAC

David W Lawson & Ruth MaceHuman Evolutionary Ecology Group

University College London

Tracking Family Structure in ALSPAC

1. Family Structure Data in ALSPAC

2. An Example of Using the Data

Lawson, D.W. & Mace, R. (submitted). Trade-offs in modern parenting: a longitudinal study of sibling competition for parental care. Evolution and Human Behavior

- Fathers- Siblings

400+ variables reference family structure.

Most data unevenly distributed across 6/7 key points:

(mother questionnaires)

(Child questionnaires)

With other relevant data spread in between.

A G H J M Q N??

KB KD KQ KU

Distribution of Family Data in ALSPAC

Tracking Fathers: A. Parental Relationship at Birth

75% married and cohabiting

16% unmarried cohabiting

5% unmarried not cohabiting

i. Mother’s Relationship to Child’s Father in Pregnancy

A

(Mother’s Questionnaire A: a520, a521)

Tracking Fathers: A. Parental Relationship at Birth

A

ii. Prior Length of Relationship to Child’s Father at Pregnancy

(Mother’s Questionnaire A: a523yy)

Mode: 3 years

Tracking Fathers: B. Father Presence Over Time

A G H J M Q

i. Option 1: Age at which biological father leaves

(Key Point Data: g521, h401, j375, Mc4b1yr, Mc4b1mth, QC4bi)

20% of absent fathers, absent from birth.

Advantages:Gives us exact age dad left.

Disadvantages:Doesn’t tell us about “replacement” father figures.

A G H J M Q

ii. Option 2: Live-in Father-Figure Variable x Cohab data

(Key Point Data: h400 ,h376 , j374, j365b, Mc4a, Mc1b2, g520, g506, g521, h401, j375, Mc4b1yr, Mc4b1mth, QC4b1 QC4a, QC1b2)

Objectifies father-figure as live-in partner of mother

Advantages:Tracks non biological father figures.Can impute some missing data.Necessary for coding sibling relatedness

Disadvantages:Restricted to unevenly distributed key points

Note:Able to cross reference each option and impute some missing.

Tracking Fathers: B. Father Presence Over Time

A G H J M Q

i. Financial Investment: How frequently does the bio father provide financial support?

ii. Time Investment: How often does the bio father see the child?

(Key Point Data: g523, h403, j377, Mc4b3, QC4b3)

(Key Point Data: g522, h402, j376, Mc4b2, QC4b2)

Tracking Fathers: C. Investment from Absent Fathers

A G H J M Q

Absent fathers more likely to invest later in study period

Tracking Fathers: C. Investment from Absent Fathers

i. Option 1: Matching Repeated Questions on Cohabitation and Marital Status

Advantages:Great Survey – No. of Live in Relationships of Mother, Dates for start and end for last 4 relationships.

Disadvantages:Only available for the ~8,000 that filled in questionnaire M. No comparable surveys in later waves, stops at M.

ii. Option 2: One-off Relationship Survey at Questionnaire M (7y1m)

M

Many repeated but differently distributed questions, could be matched up:* Is mum cohabiting with partner?, * current marital status?

Disadvantages:Difficult tell if partner is changing even if mother’s status stays the same. Does not tell us about father’s relationship to the study child.

Tracking Fathers: D. Relationship Status Over Time

A G H J M Q

i. Total Number of Resident Siblings

ii. Total Number of Non-Resident Siblings

(Key Point Data: g530, g531, g532, h411, h410, h412, j382, j383, j384, Mc5a, Mc5b, Mc5c, QC5a, QC5b, QC5c)

(Key Point Data: g536, g538, g540, h415, h417, h419, j386b, j387b, 388b, Mc6anum,Mc6bnum, Mc6cnum, QC6ano, QC6bno, QC6cno)

At 10 years, 10% of families have at least one non resident sibling

Limitations:Residence is not clearly objectified e.g. does it include kids at boarding school/university?Or kids living with different carers??

Tracking Siblings: A. Number of Siblings

A G H J M Q

iii. Sum: Total Number of Siblings

Around 50% of kids are only children at birth, but only 10% are only children by Age 10.

Tracking Siblings: A. Number of Siblings

A G H J M Q

i. Number of Siblings Related to Live-in Father Figure

(Key Point Data: g530, g531, g532, h411, h410, h412, j382, j383, j384, Mc5a, Mc5b, Mc5c, QC5a, QC5b, QC5c) + Data on who the current father figure is, so we can subtract study child from total number and also know if a man is actually in the house!

Limitations:All of this data contains no information on age or sex of children…

Tracking Siblings: B. Relatedness

A G H J M Q

KB KD KQ KU

i. Centring Relative Age and Sex Data to Key Points:

(kb590, kb591, kb592, kd451, kd452, kd453, kd432, kd453, kd454, j420,j422, j4228a/b j420a/b, j422a/b, kq637, kq636a/b kq630, kq631, kq633, kq634, kq632, kq635, kud63b1bro, kud6b1sis, kud6b2bro, kud6b2sis)

Lots of imputation...

Tracking Siblings: C. Sex & Relative Age

A G H J M Q

Limitations:All of this data specifically makes reference only to currently coresident children.

Imputation leads to some inconsistencies in data…

Still don’t how actual age of siblings.

YSibs: just arrival windows

OSibs: only know DOB of next oldest from interpreg interval.

Tracking Siblings: C. Sex & Relative Age

i. Data from past relationship survey at Questionnaire M (7y 1m)

Advantages:Good Survey – DOB of each child associated with last 4 live in relationships

Disadvantages:Only available for the ~8,000 that filled in questionnaire M. Don’t have comparable surveys in later waves, stops at M.

While tells us relatedness and DOB, doesn’t tell us sex or residence of each child.

M

Tracking Siblings: D. D.O.B.

Acknowledgements

ESRC &Parkes

Foundation(Funding)

Jill Greenberg

(Images)

Jon Heron, Jean Golding &

ALSPAC (Data)

Human Evolutionary

Ecology Group

Lawson, D.W. & Mace, R. (submitted). Trade-offs in modern parenting: a longitudinal study of sibling competition for parental care. Evolution and Human Behavior

Lawson, D.W. & Mace, R. (in press). Sibling configuration and childhood growth in contemporary British families. International Journal of Epidemiology