Investment Calculation

[Daniel O'Grady]

From what I know cap rate is calculated as NOI/Value of Asset (Down payment+amount financed). While the cap rate seems like an OK calculation, it does not include the part you pay for financing so it is possible to have a positive cap rate with negative cash flow.

Would a another useful calculation be your total net income/value of asset? It seems like this would be good since it looks at the whole picture while cap rate calculation only looks at part of the picture. 

Is this calculation commonly used? If so what is called?

If it is not used, why?