83% Chance of Patent Term Extension Due to USPTO Delay

According to Professor Crouch at Patently-O,

[As shown by the histogram], 72% of the issued patents include at least some 154(b) extended patent term. Among those with an extended term, the average extension is 392 days. Slightly over 10% of the issued patents were granted an extension of three months (0.25 years) or less. A cumulative frequency chart of this same data would show that just over 50% of all the issued patents have a term extension lasting more than six months.

. . . Of course, the extension term is correlated with the length of time in prosecution. This scatter plot shows that relationship quite well. . . .

. . . Primary examiners are “quicker” — i.e., that patents examined by a primary examiner issue more quickly and with fewer amendments than those examined by assistant examiners. . . . As may be guessed, issued patents associated with an “assistant examiner” are much more likely to have an extension. (78% of patents with assistant examiner have extension compared with 69% of patents examined only by a primary examiner). It appears that at least some of the quickness is due to the examiner actually acting more quickly (rather than merely compromising more easily).

Similarly, continuations are much less likely to receive extensions than patents without any ancestral history. (78% of patents with no ancestry have extension
compared with only 61% of patents that reference one or more parent). That
result is explained by the PTO’s procedure of reviewing continuation applications on a priority basis. Combining these numbers, I find a recipe for delay: In this study a patent with no ancestry that is examined by an assistant examiner has an 83% chance of received extensions due to PTO delay.