Periodic Measurement of Advertising Effectiveness Using Multiple-Test-Period Geo
Abstract: In a previous paper  we described the application of geo
experiments to the measurement of advertising effectiveness. One reason this method of
measurement is attractive is that it provides the rigor of a randomized experiment.
However, related decisions, such as where and how to spend advertising budget, are not
static. To address this issue, we extend this methodology to provide periodic (ongoing)
measurement of ad effectiveness. In this approach, the test and control assignments of
each geographic region rotate across multiple test periods, and these rotations provide
the opportunity to generate a sequence of measurements of campaign effectiveness. The
data across test periods can also be pooled to create a single aggregate measurement of
campaign effectiveness. These sequential and pooled measurements have smaller
confidence intervals than measurements from a series of geo experiments with a single
test period. Alternatively, the same confidence interval can be achieved with a reduced
magnitude and/or duration of ad spend change, thereby lowering the cost of measurement.
The net result is a better method for periodic and isolated measurement of ad