What should be done if a higher test result is more than twice the lower test result in collocated tests?

In the context of collocated tests for radon measurement, if one test result is more than twice the lower test result, it indicates a significant discrepancy that warrants further investigation. Conducting a repeated collocated test is essential because it allows for a more reliable assessment of the radon levels in the environment. This testing can help to identify any anomalous readings, verify the consistency of the measurements, and ensure accurate reporting.

Repeated collocation ensures that any variations due to equipment malfunction, environmental factors, or measurement errors can be identified and addressed. This approach aligns with best practices in radon measurement, as it promotes accuracy and validity in the results obtained. The other options would not adequately address the discrepancy noted in the initial testing, which is why choosing to conduct a repeated collocated test is crucial for ensuring reliable data and maintaining safety standards in addressing radon exposure.