Such as the avg persons per household. 1/1s can be profitable as well, but you have to make sure the demographic matches up to the unit mix for that area.

For income, you can consider the 3x of the rental rate “household” income and consider both tenants together, but I wouldn’t use this as justification to abbreviate your application process.

Usually at that price point you are going to be dealing with low income households and will have issues with collecting rent. 

In our household the rental income does all the heavy lifting (covers living expenses) and her income is more like Monopoly money, and goes towards mani/pedi/massages, and crazy expensive "healthy" foods that she loves.

My 2013 was to find a new household in Washington (I had to move for my job ) that would eventually transtion to a rental; rent ou my old primary residence in Georgia, and rebuild my reserve / cash available that i used to put down a dopwn payment . 

If you're solely relying on rental income or are you refinancing and taking a cut of that for your own household, cars, bills, vacation, investments, etc as you continue to reinvest. 

You have 3 other people in your immediate family that will follow your lead, as the first generation english speaker and from what it sounds like, the financial head of household.

The scenario is you are just starting out and have $100,000 cash to begin investing in real estate, you also have no debts besides residential operating expenses and a mortgage that consumes a total of 70% of your household income.

According to a recently published "Business Insider" article, the average American spends close to 35% of their household income on housing.

Of the top 20 or so largest metro areas in the country, DC is the most affordable with median home prices being roughly 4 times the median household income.