From Property Talk Community Wiki
Yield on Purchase Price or Current Value
In each calculation of yield the value of the property can be taken as either the purchase price, or the current value. Each of these different figures provides different information. Using yield on purchase price allows the comparing of two or more potential purchases to assess which has the better return. Yield on current value in contrast allows the assessment of how an investment is presently performing and in particular whether it would be better to switch the resources invested into that property into another investment.
For example assuming all else is equal if an investor has a property whose net yield on purchase price is 5% but on current value is 1% and they could sell that property and buy another property for the same price with a current net yield of 5% then it would seem likely that they should sell the first property and purchase the second property.
