Does cap rate matter while house hacking?

[Tyler Uenaka]

Hey guys I'm new to buy n hold investing and I'm looking to get my first property in Vegas as a house hack with a 3-4 Unit Multi Fam. I'm wondering if Calculating cap rate really matters with residential properties let alone a house hack deal? 

If it does matter, then lets say I got a 4 unit, when calculating the cap rate should I be using the income from the 3 units I'll be renting out? Or should I include the potential rent of the one I would be living in as well?