[VadeRetro]

. . . but 1 in 4 times 106 and 1 in 4 times 10⁶ are both too big to be probabilities. Maybe "likelihood" means "one in x."

[longshadow]

but 1 in 4 times 106 and 1 in 4 times 10⁶ are both too big to be probabilities.

I think they are paraphrasing Arp's conclusion, which was that the probability of the conventional explanation of the observed redshift was "one in four million"..... i.e., highly unlikely.