What Is an Ideal Net Operating Income Percentage?

[Aqeelah M.]

Hello! I'm reading the Bigger Pockets article Net Operating Income (NOI) in Real Estate: What It Is & How To Calculate It

Under the heading What Is an Ideal Net Operating Income Percentage?, there is a statement that says 

"Generally, it’s best to look for properties in the real estate market with higher net operating income figures when compared to the property price. Most real estate professionals and investors agree that margins and operating incomes should be above 15% of the investment cost."

Can someone describe what this means in simple terms? 

Does investment cost mean operating expenses - debt service - capex?

What does margins mean in this scenario? 

Thanks!