Calculating Social Impact

Figuring out how to calculate the social impact I'm going for has been something I've been trying to figure out for a while. On one hand, the social good I'm trying to achieve is economic development, which in theory should be by nature easier to monetize that other social benefits. However, there are also secondary benefits, like improved perception of Pittsburgh on the part of newcomers, that I think will also happen, although that is just a theory at this point.

The theory behind onlyinpgh creating a positive economic effect for neighborhoods is based on the idea that a lack information about a place is a disincentive to to go there. For example, someone might have heard of Lawrenceville and may even know that it's generally a hipper part of the city, but if they're unsure what exactly are good places to go or events to attend, they will be less likely to go there and more likely to either stay home or stay near their home. Just as transportation is seen as a net economic benefit by making markets more accessible, information works similarly by increasing demand through broadening the customer base.

I'm confident in that theoretical model based on market research and literature searches I've done, but the problem with measuring the impact onlyinpgh will have is that there are a lot of confounding variables. Information is a factor that goes into someone's decision to go somewhere, but there are many, many others, so sorting out the amount of net benefit created through onlyinpgh is difficult. This is also true with the other benefits I think may happen but have less theoretical backing for. If I'm surveying people's perceptions of Pittsburgh and it gets better over time, there really isn't any way to empirically prove what portion of that was due to me.

My idea right now to measure benefit is to actually run some experiments using onlyinpgh when it is up and running. For example, I can give people a survey about their perceptions of Pittsburgh before and after using onlyinpgh and compare the results to a control group. Or, I can survey people after they've used the system to see if using it resulted in them going to a part of the city they wouldn't have otherwise.

Both of these would be hard and resource-intensive, however--any suggestions for other ways to isolate onlyinpgh's social benefit?