What condition should be met regarding devices when conducting sequential tests?

When conducting sequential tests in radon measurement, it is essential to use similar devices. This ensures consistency and reliability in the data collected over different testing phases. Similar devices typically have the same detection thresholds, calibration, and response times, which minimizes variations that could arise from using disparate technologies. When tests are performed with similar equipment, any differences in radon levels can be attributed more accurately to variations in radon concentration over time rather than inconsistencies inherent to the devices themselves.

Using different devices in sequential tests could lead to discrepancies in measurements as each device may have different biases or sensitivities. The choice of a single device for all tests could also lead to limitations in understanding the comprehensive environmental radon dynamics unless that device is adequately calibrated and tested. Not requiring a device is irrational in the context of radon testing since a method must be employed to measure radon levels accurately. Thus, using similar devices is vital in maintaining the integrity of the test results.