How to calculate % of population that overlaps another polygon?

[KathrynAngleton]

I am trying to figure out what percentage of my City's population falls within a certain distance of their parks. I created a 10-min walkshed via network analyst, but my population data is limited. The best I have is Census Block Groups (2014-5 year estimates). Since I don't have points for population or even just household points with household sizes in the attribute table, I'm relying on the BG polygon. I know I can intersect the BG poly with the parks network analyst output poly, but how do I calculate the percentage of the population (a field within the BG attribute table) overlaps with the parks output? Is there a better way to do this? Any ideas, input, or advice is greatly appreciated. Also, I do not have BAO or BA Desktop, I know those tools can generate population numbers based on polygon inputs.

[Robert_LeClair]

Another workflow is to use Modelbuilder to do the analysis.  There is a tool - Make Feature Layer that uses a ratio policy - basically a percentage split on the population field based upon an intersect.

[KathrynAngleton]

Hey Robert, I actually tried that originally and wasn't entirely confident in the results that came back. It was probably more so the data I was using rather than the process itself. I realized I should have been using 2010 census data rather than the 2014 estimates. What I ended up doing was selecting by location having their centroids within. May not be as fancy, but the results came back closer to what I was expecting. Thanks for the input, though!