Hello There, Guest!  

[OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer

#17
It's untrue that ACE model specifies additive heritability. It's not even clear if some experts understand it well, or not. Here's an illustration :

Haworth, C. M. A., Wright, M. J., Luciano, M., Martin, N. G., de Geus, E. J. C., van Beijsterveldt, C. E. M., ... & Plomin, R. (2010). The heritability of general cognitive ability increases linearly from childhood to young adulthood. Molecular Psychiatry, 15, 1112-1120.

Now, click on it, do CTRL+SHIFT+F, type "additive". You get 4 hits. Now, read these sentences.

Quote:These genetic and environmental effects are commonly represented as A, C and E. ‘A’ is the additive genetic effect size, also known as narrow heritability.

How is it wrong ? Well, I have written an article on income mobility where, at some point, I talked about "genoeconomics". Here's the paragraph that will help to understand this problem :

Quote:Similarly, Hyytinen et al. (2013) showed, using the Older Finnish Twin Cohort Study for Finland, with MZ and DZ pairs of 620 and 1146 for women and 494 and 1094 for men, that 24% and 54% of variance in lifetime income for women and men, respectively, is due to genetic factors, whereas shared environment is small. The authors begin to cite studies showing that schooling reforms have enhanced earnings mobility. As explained above, this is irrelevant due to its weak intergenerational transmission through the family.

The income data was from administrative registers and thus do not suffer measurement errors due to misreporting. For their analysis, they use the Defries-Fulker regression method, which can be formulated as INC1=β0+β1INC2+β2R+β3(INC2*R)+ϵ, where INC is income, β0 is the intercept, β1 is a measure of shared environment ©, β2 is a coefficient of genetic relatedness (r=1.00 for MZ and r=0.50 for DZ twins, and thus assumes full additivity), β3 the heritability, ϵ the error term (E) which includes both the non-shared environment as well as measurement error. It is possible to include a parameter for non-additive genetic effect, or dominance (D), which in this case can be denoted as β4(INC2*D), where D=1.00 for MZ and D=0.25 for DZ twins. This can be called the ADE model, where β3 and β4 evaluate the additive (i.e., narrow) and non-additive heritability for income. The sum of the additive (A) and non-additive (D) is called the broad-sense heritability. Thus the difference between ACE and ADE models is that the former, but not the latter, assumes the heritability is purely additive.

[Image: heritability-of-lifetime-income-hyytinen...able-3.png]

We read the results from their model fitting in table 3. For females, shared environment © is small (0.10) in the ACE model whereas for males the C parameter is negative and this is indicative of dominance (D) effect, since C is the mirror of D, and conversely. For both gender group, based on the model fit index Akaike (AIC) the AE has the worst fit but the ACE and ADE have equal fit. At first glance, one believes it is impossible to select among them. However, given that D is negative for women, this model is probably ill-specified and thus they have (rightly) opted for the ACE. Because C is negative in ACE and this in turn is suggestive of large D parameter, which is confirmed in ADE model, the authors have correctly chosen the ADE as the preferred model for men. In the ACE, women and men have a heritability of 0.24 and 0.77. In ADE, the A and D parameters for women amount to 0.54 and -0.20 and for men to 0.07 and 0.47. The sum of A and Z gives a broad heritability of 0.54 for men. Given that ACE should be preferred for females, their heritability is 0.24. Interestingly, they note (table A2) that the use of a broader measure of income (which includes capital income and transfers, such as unemployment benefits and parental leave benefits) has improved the heritability estimates, which were 0.42 and A+D=0.26+0.33=0.59 for women and men, given their respective preferred model, AE and ADE. This provides another illustration of how measurement errors can reduce heritability.

When they attempt to add education as covariate in the regression, thus holding education constant, the parameter estimates (A,C,D,E) remain somewhat unchanged compared to table 3, even though heritability has diminished somewhat. When education effect is deducted from income, the A, C, D and E parameters appear similar.

In other words, before talking about additive heritability, you must test ACE against ADE. If the D component is clearly larger than 0, you probably have to select it, and then look at the A component. But unless you test models vs models, you can't have any certainty about what is additive and what is not.

The A in ACE is just an assumption, and it must be tested to see if that holds or not.
 Reply
 
Messages In This Thread
[OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Chuck - 2014-Jul-14, 06:25:48
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Emil - 2014-Jul-14, 10:45:09
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Meng Hu - 2014-Jul-14, 19:57:08
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Jul-19, 22:37:13
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Aug-05, 22:39:40
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Emil - 2014-Aug-07, 19:25:59
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Aug-07, 22:27:33
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Aug-08, 00:32:10
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Aug-19, 03:11:37
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Emil - 2014-Aug-08, 00:29:43
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Emil - 2014-Aug-19, 09:36:33
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Aug-19, 19:22:42
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Duxide - 2014-Aug-19, 19:33:48
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Aug-19, 20:27:44
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Duxide - 2014-Aug-19, 20:56:25
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Emil - 2014-Aug-19, 21:23:08
RE: Genetic and Environmental Determinants of IQ - by Meng Hu - 2014-Aug-21, 01:11:58
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Aug-21, 01:25:25
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Meng Hu - 2014-Aug-21, 02:29:13
RE: Genetic and Environmental Determinants of IQ - by Dalliard - 2014-Aug-21, 19:58:04
RE: Genetic and Environmental Determinants of IQ - by Meng Hu - 2014-Aug-21, 21:11:34
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Aug-21, 23:43:11
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Duxide - 2014-Aug-21, 22:57:35
RE: Genetic and Environmental Determinants of IQ - by Dalliard - 2014-Aug-21, 23:45:22
RE: Genetic and Environmental Determinants of IQ - by Meng Hu - 2014-Aug-22, 04:19:42
RE: Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Americans - by Chuck - 2014-Aug-22, 04:25:14
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Meng Hu - 2014-Sep-02, 23:40:26
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Chuck - 2014-Sep-03, 02:48:14
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Meng Hu - 2014-Sep-07, 01:49:42
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Chuck - 2014-Sep-07, 19:35:52
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Duxide - 2014-Sep-08, 13:02:31
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Chuck - 2014-Sep-08, 15:16:27
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Emil - 2014-Sep-07, 21:44:22
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Chuck - 2014-Sep-07, 23:34:54
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Emil - 2014-Sep-07, 23:51:24
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Meng Hu - 2014-Sep-08, 00:21:20
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Emil - 2014-Sep-08, 00:36:38
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Emil - 2014-Sep-08, 15:04:06
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Duxide - 2014-Sep-08, 17:48:27
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Duxide - 2014-Sep-08, 18:01:30
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Chuck - 2014-Sep-08, 19:44:52
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Duxide - 2014-Sep-08, 19:48:12
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Chuck - 2014-Sep-11, 23:19:01
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Duxide - 2014-Sep-12, 10:53:22
RE: [OBG] Genetic and Environmental Determinants of IQ - by Dalliard - 2014-Sep-09, 21:25:33
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Meng Hu - 2014-Sep-10, 01:12:35
RE: [OBG] Genetic and Environmental Determinants of IQ - by Dalliard - 2014-Sep-11, 18:27:00
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Emil - 2014-Sep-11, 23:29:03
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Chuck - 2014-Sep-11, 23:35:43
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Emil - 2014-Sep-11, 23:44:40
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Meng Hu - 2014-Sep-12, 01:30:14
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Emil - 2014-Sep-12, 02:26:19
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Duxide - 2014-Sep-12, 22:59:24
RE: [OBG] Genetic and Environmental Determinants of IQ in Black, White, and Hispanic Amer - by Chuck - 2014-Sep-14, 21:11:40
 
Forum Jump:

Users browsing this thread: 1 Guest(s)