After retraining staff, return to the field and attempt to re-collect the necessary data.
This is the most costly decision because it requires either re-contacting the original participants to collect the necessary data or recruiting additional participants. These are some possible outcomes:
|  | The research staff is able to contact about 90% of the original participants, and about 3/4 of those agree to come in for additional testing.
|  | The research staff is able to contact about 75% of the original participants, and only about half of those agree to come in for additional testing.
|  | The research staff is able to contact about 50% of the original participants, and only about 10% of those agree to come in for additional testing. The decision is made to begin additional recruitment.