Randomized Block Designs - Where Might You Apply Them? 2121 unread replies.2121 replies. Think of a specific situation in your field of study or future career where experimental units might be heterogeneous, and using a completely randomized design would not be ideal. Describe this scenario with sufficient detail so it is clear where there may be differences in the experimental units. For example, consider a scenario similar to the air traffic controller stress test, where individual differences among subjects could significantly impact the results. Indicate your identified blocks and what "treatments" would you compare