I'm considering using difference in difference techniques to write my last two undergraduate papers relating minimum wages and employment/poverty. I've been told issues arise with using aggregate data like you would find on major statistical sources. I have notice most DID papers use survey data, however i do not have access to this or time to get it.
So, my question is: what are the issues with not using micro-level data? how big of a deal is it? and are there possible solutions?