What is the most representative way to measure the impact of a digital signage deployment?”
I’m not sure there is a one-size-fits-all answer to this question, given the fact that digital signage deployments vary based on the overall objective of the media owner or end user.
In our case, we are relying on third-party measurement via Nielsen’s Place-Based Video Report as well as closely monitoring engagement with our interactive content. For the latter, we look to see what interactive features riders are engaging with the most depending on the location of an individual kiosk. This gets a little complicated with our current scenario in which we have two distinct user interfaces, but we are still able to glean the content with which riders are engaging. Knowing which features riders interact with most arms us with the information we need to improve the offering and to understand what sticks.
My advice would be to decide what it is you want to glean from your metrics. Understanding how you measure impact will be based on your objectives at deployment, which differ from another end user or network operator.