[en] Owing to the short-lived nuclides present in the decay chain of radon and the complexity of environmental parameters, the behaviour of radon daughters in the environment is rather complicated. Therefore, errors are easily induced in the measurements of radon daughters. In this investigation 10 methods developed by several investigators compiled as a software package were reviewed and tested one by one in a radon environment with known concentrations. The Alpha Smart 770 of Alpha Nuclear Canada was used to evaluate and make comparisons among these ten methods. Consistent results within an error of 6% were obtained for six methods. However, inconsistent results within an error of from 24% up to a factor of 4 were obtained for the other four methods. It is concluded that the method to be used should be evaluated before routine or large-scale sampling is planned. (author)