|Figure 1: Fictitious data showing spurious correlation between
height and reading ability| |Figure 2: Model showing how a
spurious correlation between height and reading arises because
both are affected by age| |Figure 3: 95% confidence interval
around estimated correlation of .5, with different sample sizes|
|Figure 4: Correlations obtained in samples of dyslexic (red)
and controls (blue) for 20 runs of simulation with N = 30 per
group.| |Figure 5: Models of causal relationships underlying
observed correlation between auditory deficit and language
impairment| - We found that, when studying heritable conditions,
it is useful to include data on parents or siblings. Models
differ in predictions about how measures of genetic risk - for
instance, family history, or presence of specific genetic
variants - relate to A (auditory deficit) and B (language
impairment) in the child. This approach is illustrated in this
paper. Interestingly, we found that the causal model that is
often implicitly assumed, which we terme