1 Normal Distribution

Here we plot the normal distribution
K: lifetime risk of disease, the proportion of the normal distribution
T: The threshold
z: height of normal curve at T
i: mean liability of affected group = z/K

mx=4
z <- seq( from=-mx, to=+mx, by=.01)
dens <- dnorm(z)
plot( z, dens, type="l",lwd=5,yaxt="n",xaxt="n",ylab="",xlab="",frame.plot=F)

K=0.10  # lifetime risk of disease
t=qnorm(1-K) # Threshold
x.shade <- seq(t,mx,0.01)
n=length(x.shade)
polygon(c(rev(x.shade),x.shade),c(rep(0,n),dnorm(x.shade,0,1)),col="red")