data_y: Simulated response variable
Description
A toy example is simulated from the functional form of
$data_y = sin(2*pi*x1) + 4*(1-x2)*(1+x2) + sqrt(0.5) * rnorm(1)$, where x1 and x2 are
simulated from a uniform distribution between 0 and 1.format
A vector of 50 observations