gen_model: Samples effect sizes for the disease model
Description
The generated disease model is the list of effect size coefficients.
The list comprises the following fields: 'syner', 'marg' and 'inter'.
'syner' is itself a list of numeric vectors with two entries named
'A0' and 'A1'. 'A0' refers to the vector of effect sizes when the target
variant \(A = 0\). Similarly, 'A1' refers to the vector of effect
sizes in the case \(A = 1\). The two other entries 'marg' and
'inter' are, respectively, the marginal and epistatic effect sizes. The
effect sizes are independent and normally-distributed. The mean
parameter is either a list of vectors or a vector of length 4. If
mean is a vector, then the effect sizes for each type of effects have
the same mean. Otherwise, the corresponding vector in the list
specifies their individual means. The same logic applies to sd, the
standard deviation parameter. For coherence, the parameters mean and
sd are encoded in the same order as the output.