 The Monte Carlo design considers several sparsity structures (sparse, dense, block) and error structures (i. i.d. errors and heteroskedastic errors).
<meaning-changed>  The Monte Carlo design considers several sparsity structures (sparse, dense, block) and error structures (i. i.d. errors and heteroskedastic errors).
 The Monte Carlo design considers several sparsity and error structures (i. i.d. errors and heteroskedastic errors).