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Author Date.  Introduction ◦ Hypothesis ◦ Significance ◦ Definitions ◦ Pathway  Methods  Results  Conclusion  Q&A.

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Presentation on theme: "Author Date.  Introduction ◦ Hypothesis ◦ Significance ◦ Definitions ◦ Pathway  Methods  Results  Conclusion  Q&A."— Presentation transcript:

1 Author Date

2  Introduction ◦ Hypothesis ◦ Significance ◦ Definitions ◦ Pathway  Methods  Results  Conclusion  Q&A

3  Among the population of adolescents in the study, younger siblings of dyad pairs born further apart from their older siblings will have higher cognitive scores than those born closer to their older siblings.  That is, you’ll be smarter if your parents have you and your sibling further in time apart.

4  How much time should you plan to set aside to have smart kids?  What makes you smarter than your younger sibling?

5  Birth spacing # months between sibling birth dates  Cognitive Ability ◦ Peabody Picture Vocabulary Test

6  More attention for child  Different interaction between siblings  More resources for care

7  Mostly infant and early childhood samples  Contradicting results ◦ Yes, there is an association 1,2,4,5,7,8, 11 ◦ No, there is no association 3,5, 6, 9, 10, 11  Weak controls in adolescent studies

8  Study of adolescents  Stronger control for SES, gender, birth order, family size  Different cognitive measure

9  Introduction  Methods ◦ Study design ◦ Exposure & Outcome variables ◦ Covariates ◦ Models & Interaction  Results  Conclusion  Q&A

10  Child Health and Development Study  Prospective, longitudinal  Kaiser Foundation Health Plan, Oakland, California  Women and their children born 1959 – 1967  Adolescent Study (born between 1960 – 1963)

11 *also excludes 9 records with inconsistent family size between PREPROD and ADOL 20,754 - Children w/severe anomalies 20,036 - Multiples 19,605 - Children whose mother had hypothyroidism 19,571 - Children not born 1960-1963 9,421 - Children not followed in Adolescent Study 1,900 - Children w/stepsiblings 1,768 - Children w/>1 sibling 384 - Children w/o Peabody score 375 - Children w/older sibling alive at Adol Study* and < 18 yrs older 364 135Younger siblings 22935382537 Older siblings<2 yrs2-3 yrs3.1-4 yrs> 4 yrs

12  Birth space interval = birthday of younger sibling – birthday of older sibling  3 versions of exposure: ◦ Categorical exposure ◦ Continuous exposure ◦ Dual exposure (categorical and continuous)

13  Version 1: Categorical (5) ◦ Second-born  ≤2 years  2.1-3 years  3.1-4 years  >4 years ◦ First-born  Version 2: Continuous (months)

14  Version 3: Dual ◦ Categorical  First-born  Second-born ◦ Continuous (months)

15  Continuous Peabody score (points)  In general: ◦ SD = 15 ◦ Range = 0 to 160  In sample: ◦ Range = 71 to 156 ◦ Mean = 117.9 ◦ SD = 14.3

16 maternal ageracechild sexsibling sex delivery type smokingchild age head circumference social class marital status low birthweight preterm alcohol

17 maternal ageracechild sexsibling sex delivery type smokingchild age head circumference social class marital status low birthweight preterm alcohol

18 maternal ageracechild sexsibling sex Smokingalcoholchild age head circumference social class low birthweight preterm Significance at p < 0.2

19 maternal ageracechild sexsibling sex smokingalcoholchild age head circumference social class low birthweight preterm

20 Significance: >10% change in coefficient of at least 1 exposure category maternal ageracechild sexsibling sex smokingalcoholchild age head circumference social class low birthweight preterm

21 Significance at > 10% change in coefficient of at least 2 exposure categories maternal age racechild sex smokingchild age social class

22 Categorical Birth spacing Continuous birth spacing Dual birth spacing FullModel 1Model 2Model 3 RestrictedModel 4Model 5Model 6 Interaction, Restricted Model 7 Model 8 Model 9 Model 10 N/A

23  Continuous birth spacing variable  B = 0.001, p = 0.13 Tiny magnitude Pretty linear

24 Continuous exposure model  Significance set at p < 0.2: 1.Birth spacing /race 2.Birth spacing /child sex Revised model  Significance set at p < 0.2: 1.Birth spacing /child sex 2.Race /child sex 3.Birth spacing / child sex / race

25  Introduction  Methods  Results ◦ Categorical Model ◦ Continuous Model ◦ Dual Model ◦ Interaction  Conclusion  Q&A

26 CharacteristicB95% CI Birth spacing Second- born ≤2 yrs-- Second- born 2.1-3 yrs-3.1(-8.9, 2.7) Second- born 3.1-4 yrs-0.7(-7.3, 5.8) Second- born >4 yrs*-9.4(-15.3, -3.5) First-born-2.7(-7.2, 1.9) Maternal characteristics Upper class (v. lower)*6.7(3.9, 9.5) White (v. other)*7.8(4.5, 11.2) Age (years)*0.4(0.2, 0.7) Smoking (yes v. no)*-3.9(-6.7, -1.2) Child characteristics Male (v. female)1.1(-1.5, 3.8) Age*4.3(2.1, 6.5) * p < 0.05

27 CharacteristicB95% CI Birth spacing (months)*-0.1(-0.2, -0.02) Maternal characteristics Upper class (v. lower)*2.3(2.3, 11.4) White (v. other)2.9(-2.2, 9.5) Age (years)0.2(-0.2, 0.7) Smoking (yes v. no)2.4(-8.6, 0.7) Child characteristics Male (v. female)2.2(-3.7, 5.1) Age2.2(-1.6, 7.0) * p < 0.05

28 CharacteristicB95% CI Birth spacing (months)*-0.1(-0.2, -0.1) Maternal characteristics Upper class (v. lower)*6.5(3.7, 9.2) White (v. other)*8.0(4.7, 11.4) Age (years)*0.5(0.2, 0.7) Smoking (yes v. no)*-3.7(-6.4, -0.9) Child characteristics Male (v. female)1.1(-1.5, 3.8) Age*4.5(2.3, 6.7) * p < 0.05

29 CharacteristicB95% CI Intercept β0β0 *108.3(100.7, 115.9) Birth spacing (years) β1β1 -0.6(-4.3, 2.8) Maternal characteristics Upper class (v. lower) β2β2 *5.8(1.3, 10.2) White (v. other) β3β3 *9.9(1.7, 18.1) Age (years) β4β4 0.2(-0.2, 0.6) Smoking (yes v. no) β5β5 *-4.0(-8.6, 0.5) Child characteristics Male (v. female) β6β6 *10.9(0.9, 20.9) Age β7β7 3.0(-1.2, 7.3) Interaction Birth spacing / white β8β8 0.3(-3.5, 4.1) Birth spacing / male β9β9 *-8.5(-16.6, -0.4) White / male β 10 *-11.7(-22.9, -0.48) Birth spacing/white/male β 11 *7.1(-1.2, 15.5) *p < 0.1

30 Slope (year)95% CIRegression equation White boys -1.8 (-3.3, -0.3) Y = B 0 + (B 1 + B 8 + B 9 + B 11 ) yr + B 3 + B 6 + B 10 Other boys -9.2 (-16.5, -1.9) Y = B 0 + (B 1 + B 9 ) yr + B 6 White girls -0.5 (-1.9, 1.0) Y = B 0 + (B 1 + B 8 ) yr + B 3 Other girls -0.8 (-4.3, 2.8) Y = B 0 + B 1 * yr ** holding other covariates constant

31

32

33  Introduction  Methods  Results  Conclusion ◦ Summary ◦ Limitations & Strengths ◦ Future Directions  Q&A

34  Slight inverse relationship between birth spacing and Peabody score  Negligible difference in Peabody score  Interaction from gender and race

35  Small sample size  Limited information on first-born siblings ◦ No PREPROD record  Unable to compare scores within dyad  Operationalizing cognitive ability

36  Statistical rigor ◦ Limiting confounders ◦ Extensive covariates list ◦ Interactions

37  Bigger sample size  Designs that can account for what we could not ◦ Different family sizes ◦ Intra-family differences in Peabody score ◦ Missing covariates  Exploring variables underlying interactions

38  Introduction  Methods  Results  Conclusion  Q&A ◦ Thank you!

39 1. Breland HM. Birth order, family configuration, and verbal achievement, Child Development. 1974;43:1011–1019. 2. Dandes HM and Dow D. Relation of intelligence to family size and density, Child Development. 1969;40: 641–645. 3. Gibbs ED, Teti DM, Bond LA. Infant-Sibling Communication Relationships to Birth-Spacing and Cognitive and Linguistic Development. Infant Behavior and Development. 1987;10(3):307-324. 4. Kamin KD, Kubinger, Schubert MR. Sibling constellation and intelligence in behavior disordered children, Zeitschrift fur klinische Psychologieforschung und Praxis. 1981;10:98– 109. 5. Lancer I, Rim Y. Intelligence Family Size and Sibling Age Spacing. Personality and Individual Differences. 1984;5(2):151-158. 6. Lewis M, Jaskir J. Infant Intelligence and its Relation to Birth Order and Birth Spacing. Infant Behavior and Development. 1983;6(1):117-120. 7. Nuttall EV and Nuttall RL. Child spacing effects on intelligence, personality, and social competence, Journal of Psychology. 1979;102:3–12.

40 8. Record RG, McKeown T, Edwards HH. An investigation of the difference in measured intelligence between twins and single births, Annals of Human Genetics. 1970;84:11–20. 9. Rodgers JL, Rowe DC. Does Contiguity Breed Similarity? A Within-Family Analysis of Nonshared Sources of IQ Differences between Siblings. Dev Psychol. 1985;21(5):743- 746. 10. Teti DM, Bond LA, Gibbs ED. Sibling-Created Experiences Relationships to Birth-Spacing and Infant Cognitive Development. Infant Behavior and Development. 1986;9(1):27-42. 11. Wagner ME, Schubert HJP, Schubert DSP. Effects of Sibling Spacing on Intelligence Interfamilial Relations Psychosocial Characteristics and Mental and Physical Health. Reese, H.W.(Ed.). Advances in Child Development and Behavior, Vol.19.X+260p.Academic Press Inc., Publishers: Orlando, Fla., Usa; Academic Press Inc.(London) Ltd.: London, England. Illus. 1985:149-206.


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