Strategies for Dealing with the Problem of Non-Overlapping Units of Assignment and Outcome Measurement in Field Experiments

Researchers conducting eld experiments are sometimes faced with the challenge of analyzing eld experimental results when the unit of assignment does not coincide with the unit of outcome measurement. For example, in electoral research it may be the case that election results are reported at a level of geography de ned by electoral law while the assignment of treatment can only be made at a level of geography di erent from this. Using examples from eld experiments conducted in Canada and Mexico, we describe this problem and its consequences for analysis and inter- pretation of eld experimental data and results. We also o er a number of practical solutions analysts can employ when faced with non-overlapping units of assignment and outcome measure in eld experiments.