Optimal Test Design Approach to Fixed and Adaptive Test Construction

Use the optimal test design approach by Birnbaum (1968, ISBN:9781593119348) and van der Linden (2018) in constructing fixed and adaptive tests. Supports the following mixed-integer programming (MIP) solver packages: 'lpsymphony', 'Rsymphony', 'gurobi', 'lpSolve', and 'Rglpk'. The 'gurobi' package is not available from CRAN; see < https://www.gurobi.com/downloads/>. See vignette for installing 'Rsymphony' package on Mac systems.