Measuring this is hard, but Gaétan de Rassenfosse (Ecole Polytechnique Fédérale de Lausanne) and four co-authors from University of Melbourne and Swinburne University of Technology think they have found the answer. Examining 1.2 million granted and refused patent applications in the US, Europe (EPO), China, Japan, and South Korea, they think they have the answer. They have posted a draft on SSRN, and the abstract is here:
Failure to obtain a patent weakens the market position and production chain of enterprises in patent-intensive technology domains. For such enterprises, finding ways to maximise the chance to obtain patent protection is a business imperative. Using information from patent applications filed in at least two of the five largest patent offices in the world between 2000 and 2006, we find that the ability to obtain patent protection depends not only on the quality of the invention but also on the quality of the patent attorney. In some cases, the latter is surprisingly more important than the former. We also find that having a high-quality patent attorney increases the chance of getting a patent in less codified technology areas such as software and ICT.They use a clever approach with their multi-country methodology to separate attorney quality from invention quality. By estimating grant rates across countries for the same inventions as well as for the same attorneys, they are able to estimate the marginal value added by the invention versus the attorney. For example, if different attorneys have differing results in two countries with the same invention, then attorney quality is likely at play. However, if the same attorney has differing results in two countries with the same invention, then invention quality is more likely at issue. Of course, this doesn't work with a couple of patents, but with more than one million patent applications, the estimates likely trend toward a reasonable measure of each type of quality unaffected by the other.
Using this index of quality, they then estimate the effects of attorney and invention quality. They find that, as expected, invention quality matters. But they also find that attorney quality matters--sometimes a lot. More interesting, they find that attorney quality matters more where there is more wiggle room (my term, not theirs), such as in software (as opposed to chemistry). In other words, they find empirical evidence to support the intuition that attorneys who can mold claims to avoid rejections are more likely to wind up with issued patents.
Now, the benefit isn't unbounded. Because grant rates are really high (like 85%), the marginal benefit is unlikely to be huge. One marginal estimate they make is that moving from the 10th percentile to the 90th percentile in quality increases the grant probability by 13 percentage points (e.g, from 79% to 92%). What this means is that invention quality is very important, because even the least successful attorneys are successful most of the time. Of course, this is a potential criticism, because if everything is granted, then how can we measure quality based on grant rates? The paper addresses this, arguing that there is a lot of variability, even within the same patent family. They also test on other measures of patent quality and find similar results.
The authors also make other interesting findings: external counsel increase grant rates, attorney quality doesn't seem to have an effect on foreign v. local probabilities, and attorney quality is of less importance in PCT applications. There is a lot more to the paper - including effects in different offices, on different technologies and other great information. I found this to be a really interesting and useful read.