What data do you need to justify out-of-home ad spend? How do you measure success?

OOH is admittedly something I am not too experienced in. In the past, I've run geofenced display and paid social ads but those were more or less attributable to that region, so it was a hybrid OOH and digital campaign (probably closer to a directly attributable digital campaign). 

However, my approach is always to be as close to attributable as possible. I would try my best to figure out where my target audience is and partner with vendors that can allow me to serve impressions there. For example, if I have a high concentration of target accounts in the financial district of NYC, I wouldn't run a subway ad at the 125th st station. I would work with a vendor that will let me rotate my digital ads and static signage in/around FiDi. I'd pay a premium for it too because I know the impressions there would be actually going toward my target audience. I would then take a look at direct and organic mobile traffic coming from that area period over period to determine the efficacy of that campaign. I'd also review branded term search impressions from that area and see if there was a spike. 

Overall though, OOH is about building awareness, and hopefully your OOH ad has a clear CTA; whether it's to ask users to visit a vanity URL, scan a code, or Tweet something with a hashtag, you will always want to measure your primary success KPI as the number of individuals that took action on your call to action. The secondary metrics would be web traffic from the regions you ran those OOH ads. Then lastly would be using a social listening tool to capture any mention of your ad or specific language you put on those OOH ads that you find to link back to folks' posts on social. 

OOH is something I'm eager to learn more of and practice. 

To justify out-of-home (OOH) ad spend and measure its success, you first need to start with the goals and the measures of success for those goals. You would typically need the following data:

1. Impressions

2. Reach and frequency

3. Location-specific data

To measure success, based on the goals you outlined, you would look at data such as:

1. Engagement metrics

2. Quality indicators

3. Halo effect (e.g., how much additional direct traffic did you receive in the designated market area where the campaign ran)

I encourage you to view OOH as more of a branding tactic compared to demand generation. As a result, the measures of success would need to be adjusted to support this perspective, such as not solely focusing on leads generated.