What You Need to Know About a Sample for Radiometric Dating

You need to know whether something other than radioactive decay may have changed the ratios of the parents and daughters. This can happen, for example, if a sample is contaminated with something that could either add or subtract parents or daughters. If the potential for contamination is low, your date is more likely to be accurate. And what's the third thing you need to know? The radioactive decay rate of the parent atoms, or their half life. But it's different for every radioactive isotope.