Several hundred laboratories around the world are active in radiometric dating.

Other objections raised by creationists are addressed in [Dalrymple2006a].

The overall reliability of radiometric dating was addressed in some detail in a recent book by Brent Dalrymple, a premier expert in the field. 80-81]: These methods provide valid age data in most instances, although there is a small percentage of instances in which even these generally reliable methods yield incorrect results.

A recent survey of the rubidium-strontium method found only about 30 cases, out of tens of thousands of published results, where a date determined using the proper procedures was subsequently found to be in error.

One question that sometimes arises here is how can scientists assume that rates of radioactivity have been constant over the great time spans involved.

Over a thousand papers on radiometric dating were published in scientifically recognized journals in the last year, and hundreds of thousands of dates have been published in the last 50 years.

Essentially all of these strongly favor an old Earth.The latest high-tech equipment permits reliable results to be obtained even with microscopic samples.Radiometric dating is self-checking, because the data (after certain preliminary calculations are made) are fitted to a straight line (an "isochron") by means of standard linear regression methods of statistics.In a related article on geologic ages (Ages), we presented a chart with the various geologic eras and their ages.In a separate article (Radiometric dating), we sketched in some technical detail how these dates are calculated using radiometric dating techniques.Such failures may be due to laboratory errors (mistakes happen), unrecognized geologic factors (nature sometimes fools us), or misapplication of the techniques (no one is perfect).