17 Questions
What does a non-significant Chi-square statistic indicate about the model fit?
The model fits well
How can the significance of a parameter in a model be tested?
By fixing it to zero
What happens when a parameter is dropped from a model?
The model may get significantly worse
What does it mean if a parameter is considered non-significant in terms of model fit?
It does not add much to the model
What does a Chi-square value of 5.18 with 1 degree of freedom indicate?
The parameter is significant
What is the general statistical power to detect effects of C?
Very low
What is the formula to calculate heritability (h2 or a2) using Falconer's rules?
(rMZ - rDZ) * 2
What does the shared environment component (c2) represent in Falconer's rules?
Shared environment component represents the difference between the monozygotic correlation and heritability component.
How is the non-shared environment component (e2) calculated in Falconer's rules?
e2 = 1 - rMZ
What are the steps involved in Estimation with Structural Equation Modelling (SEM)?
- Put together a theoretical model with path tracing, 2. Derive predictions from the model, 3. Compare predictions to observed relationships, 4. Use fit functions to assess, 5. Conclude the plausibility of the model if it fits well.
Explain the principle of having a maximum of one curved arrow per path in the context of modeling.
The principle limits the complexity of the model by allowing only one curved arrow per path, which helps in maintaining model simplicity and interpretability.
Why is the double-headed arrow from the independent variable to itself included in modeling?
The double-headed arrow is included to represent the latent variable's variance, even if there are other double-headed arrows in the chain.
What is the required sample size to detect a heritability of 60% with 80% power and a c2 of 10%?
62 MZ and DZ pairs
Why does detecting a c2 of 10% with a h2 of 60% require a larger sample size compared to detecting heritability?
To detect c2 of 10% with a h2 of 60%, 2200 MZ and DZ pairs are needed.
What is the problem faced in twin studies when the sample size is too small to detect a certain proportion of C?
The AE model is selected as the best model, inflating the heritability estimate.
What happens to familial effects when the C component is dropped from the model?
All familial effects will be attributed to A, resulting in a very high heritability estimate (>70%).
Why is it important to report the full ACE model along with the 95% CI in data analysis?
To provide a fair representation of the data and avoid bias in parameter estimates.
This quiz covers the concept of model fitting and assessing model fit using the Chi-square statistic derived from maximum likelihood estimation. It discusses how to determine if a theoretical model is a good description of the data and the significance of model parameters.
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