A version change that breaks a results comparison

A worked example using a hypothetical scenario to show how the reasoning applies.

The scenario

A hypothetical service changes its feature set halfway through a reported season. Combining the old and new outputs into a single unqualified performance claim conceals the change. Retain version labels and report each period with enough information to reconstruct which model made each prediction.

What to take from it

Documentation creates a review trail; it does not prove the model is accurate.

What to check next

• State exactly what the output predicts and in what units.
• Record data exclusions, test windows and baseline methods.
• Describe monitoring triggers and the response to a material change.

Keep the conclusion specific

Separate the observation, the interpretation and the unresolved question. A worksheet is most useful when its conclusion stays within the evidence entered into it.

The notebook is browser-local and contains no confidential PTPTips methodology.