• Cost structures, ethical factors, and multiple objective functions (these have already been incorporated in some of our work on other problems). Generalized cost criteria include money, time, resources, or ethical factors such as failures or expected successes lost. Costs may be optimization criteria or evaluation criteria.
• Optional (and optimal) stopping.
• Randomization

• More populations. The time/space complexity is polynomial in the sample size, but exponential in the number of populations.
• Covariates.
• Correlated populations. We are currently engaged in joint work with Connie Page involving an estimation problem where different types of observations yield different information about the same parameter. As more medical diagnostics become available, such situations will become increasingly important.
• Non-binary responses. It is extremely hard to optimize designs in such situations, and so one needs to emphasize locating "good" designs.
• Delayed responses. Note that hyperopic designs may be useful here, because they provide a natural way to incorporate partial information.
• Vastly larger sample sizes. We may use extrapolation or interpolation approaches to achieve near-optimal designs.

A related project is to explore using a variety of graphical techniques for examining procedure behavior. For example, commonly expressed complaints about the OS procedure include:

1. it is too hard to compute
2. it is too hard to understand

References Outline Points of Interest