The 1,000 covariates are from 10 blocks of independent variables, with each block consisting 100 autoregressively correlated variables. There are a total of 12 covariates affecting the response variables: \(x_{50}, x_{51}, x_{150}, x_{153}, x_{250}, x_{256}, x_{350}, x_{359}, x_{450}, x_{467}, x_{550}, x_{583}\).