This function returns a design for the regression linear model, without the intercept. The user can choose one of the two models:
"mod1" or "mod2". The first model "mod1" contains just one column, equal to \(i^2 + X_i\), \(i=1,...,n\), where \(X\) is an AR(1)
process with phi_1 = 0.5
.
The second model "mod2" contains two columns, the first equal to \(log(i) + sin(i) + X_i\) and the second equal to \(i\), for \(i=1,...,n\).
The process \(X\) is again an AR(1) process with phi_1 = 0.5
. More information about "mod2" is available in the paper of
E. Caron, J. Dedecker and B. Michel (2019). Linear regression with stationary errors: the R package slm.