Final answer:
Waiting to begin observations is not a method for dealing with reactivity; effective methods include using multiple observers, measuring behavior unobtrusively, and blending in.
Step-by-step explanation:
The ways to deal with the issue of reactivity in research include using multiple observers to increase inter-rater reliability, measuring the behavior unobtrusively to reduce participant awareness, and blending in with the surroundings to maintain a nonparticipant observer status. However, waiting to begin observations is not a recognized method for dealing with reactivity, as reactivity is related to the influence the presence of the observer has on participants' behaviors, not the timing of when the observation starts.