A worked distinction
Receiving a 2-basis-point rebate on a 10,000 USD fill contributes 2 USD. If the effective execution benchmark is 8 USD worse, the rebate alone does not make the observed execution better than the benchmark.
What to verify in your own analysis
Use signed fees, consistent buy/sell conventions and a benchmark known at decision time. Separate a posted quote from a completed fill.
Write down the market or protocol identifier, units, observation window and data source before comparing outputs. Keep unavailable values distinct from zero. Capture a baseline and change one assumption at a time so the resulting difference can be explained.
Use the linked working tools
Open the related tools below to inspect actual public observations or calculate a local scenario. The numerical example above is illustrative, not a current quote. Export the result together with its assumptions if you need a reproducible research record.
The review checklist records what you checked in this tab. Completion measures your own notes, not whether an investment is safe, suitable or profitable.