When missing hazard data gets mistaken for low risk


A missing result needs a defined operational response. Treating it as a reassuring answer can distort an otherwise careful risk assessment.

A hazard API returns a zero for one location, no value for another and an unfamiliar negative number for a third. All three responses fit neatly into a numeric column. That does not make them comparable observations.

This is a basic integration problem with significant consequences. A portfolio report may rank the locations as low risk, a quote engine may accept them automatically, or an analyst may remove them from the evaluation without noticing that the missingness is concentrated in a particular region.

Give missingness a meaning

Before using a hazard layer, establish how it represents a valid zero, an unavailable result, a point outside coverage and a failed request. Also check whether an account can access the requested layer and whether the requested period or scenario is supported.

These conditions require different responses. Retrying may resolve a temporary failure. It will not create coverage outside the dataset's scope. Requesting a different parameter may correct an invalid query, but it does not justify substituting another hazard measure without telling the user.

Keep the original response and its status where possible. If a supplier uses a numeric sentinel for unavailable data, transform it into an explicitly documented missing state before calculating summaries. Do not leave a special negative value to compete with genuine observations in a ranking.

Test the meaning of apparently valid values

Successful delivery is only one part of quality assurance. Check whether the returned value is plausible for the measure and location, and whether the unit matches the receiving system.

For example, wind speed and gust speed are different measures. A temperature in kelvin will look extreme if interpreted as degrees Celsius. A valid zero for one hazard metric may be suspicious for another. The appropriate check comes from the layer's definition, rather than a rule that every zero is either safe or wrong.

Consider a fictional insurer testing a feed across three territories. Its sample includes supported locations, known boundary cases and intentionally invalid requests. The exercise reveals that one territory returns unavailable values for a requested layer. The integration records that limitation and routes affected cases to the agreed fallback instead of assigning the lowest score.

That test has improved the workflow before any claim about predictive value has been made.

Show the missing part of the portfolio

A useful portfolio report should state the population submitted, the population assessed and the reasons other records could not be assessed. Break this down by geography and relevant property segments. Missingness that looks small overall may be substantial in the part of the book a team is trying to expand.

For modelling, compare results on available records with the effect across the intended population. For operational use, make the fallback visible to the decision owner. Options might include another evidence source, manual review or deferring a decision, depending on the workflow.

Finally, monitor changes in response patterns. A sudden improvement in apparent portfolio risk may be a change in data availability or request handling. Track missing rates and status codes alongside the scores themselves.

Chimnie's work with global peril data reinforces the importance of clear field definitions, coverage checks and exception handling. They belong in the evaluation from the first sample, alongside any assessment of the hazard information's usefulness.


If you are testing Global Perils, bring the territories, hazards and fallback requirements that matter to your intended deployment.

Put this data to work

Everything discussed here is available through the Chimnie API, with up to £16 of free balance to try it.

© 2026 Chimnie is a trading name of Little Chimney Limited. All rights reserved.

London, United Kingdom · hello@chimnie.com