proc iml;
    Cov = {1 0.3,
          0.3 1};
    X = RandNormal(&n*&nrep, {0,0}, Cov);
    ID = colvec(repeat(T(1:&nrep), 1, &n));
    n_id = repeat(&n, &n * &nrep);
    B = n_id|| ID || X;
    x = B[,3];
    z = B[,4];
    eta = 2 - 4 * x + 2 * z;
    mu = exp(eta);
    y = rand("Poisson", mu);
    B = B || eta || mu || y;
    d = {n, rep, x, z, eta, mu, y};
    mattrib B colname=d;

    create raw from B [colname=d];
    append from B;
    close raw;

run;