The Skakkebaek error is analogous to comparing the data sets and concluding that men are getting shorter in a hurry. Skakkebaek, however, drew a line between them, termed a linear regression, and announced a falling trend. This can be a serious error. One could draw a line between them, note the steeply falling temperatures, and conclude that an ice age was only a week away. In fact, a reanalysis of the data from 48 of the papers revealed a statistically significant increase in sperm concentration over the past two decades.
Recent studies draw comparable skepticism.
An analysis showing some regional decline by Dr. J. Auger in France is not convincing, since other studies have been just as likely to find regional increases. In addition, differences in age, abstinence before semen analysis, ejaculatory frequency, and the number of samples analyzed per person were not controlled for. All of these factors contribute to variation. This needs to be noted. If synthetic chemicals were reducing fertility, Colborn's strongest-case scenario is the DES tragedy, where mothers were directly fed high doses of a hormone in hopes of preventing miscarriages.