An asking price is an offer to the market
A property listing usually displays the seller's asking price. That number may incorporate negotiation room, renovation costs, the seller's expectations or a particular view of future market conditions.
It does not necessarily represent the amount for which comparable properties have recently changed hands.
A transaction price records an agreed outcome
A completed transaction reflects an agreement between a buyer and seller. Transaction datasets therefore provide a different type of evidence from current advertisements.
Historical transaction prices are still not perfect predictions of the next transaction. Market conditions change and every property has its own characteristics.
Their value is that they provide an observed benchmark against which an asking price can be considered.
Use the gap as a question, not a conclusion
If an asking price is significantly above a relevant transaction benchmark, the appropriate next step is to investigate why.
The property may have a larger parcel, superior condition, a more desirable position or characteristics that are not represented adequately by the comparison set.
Transaction-based benchmarks are therefore most useful as negotiation and research tools rather than automatic buy or sell signals.