I rent out two single family homes. You need to learn about how to analyze your return on investment, get the places rented, and deal with repairs, problem tenants, among other things. If you don’t do your research, you could easily lose money. I have to spend a few days a year managing things, checking up on the properties, finding new tenants, but it is effectively passive. I buy in areas near big universities with stable real estate markets so there is always a fresh crop of new people moving into the neighborhood.
In equity valuation, residual income represents an economic earnings stream and valuation method for estimating the intrinsic value of a company's common stock. The residual income valuation model values a company as the sum of book value and the present value of expected future residual income. Residual income attempts to measure economic profit, which is the profit remaining after the deduction of opportunity costs for all sources of capital.