e-Discovery Team

Anybody who does complex investigations is familiar with this problem. Indeed, you can argue this insight is fundamental to all of science and experimental method. Logan, David C. (March 1, 2009). “Known knowns, known unknowns, unknown unknowns and the propagation of scientific enquiry”, Journal of Experimental Botany 60 (3). pp. 712–4. [I have always wanted to quote a botany journal.]

How do you deal with the known unknowns and the unknown unknowns, the information that we don’t even know that we don’t know about? The deep, hidden information that is both obtuse and rare. Information that is hard to retrieve and harder still to prove does not exist at all. Are you chasing something that might not exist? Something unknown because nonexistent? Such as an overlooked Highly Relevant document? (The stuff of nightmares!) Are you searching for nothing? Zero? If you find it, what does that mean? What can be known and what can never be known? Scientists, investigators and the Secretary of Defense alike all have to ponder these questions and all want to use the best tools and best people possible to do so. See: Deconstructing Rumsfeld: Knowledge and Ignorance in the Age of Innovation (Inovo 5/114).

Seeking Knowledge of the Unknown Elusion Error Rate

These big questions, though interesting, are not why Judge Johnston started his opinion with the Rumseld quote. Instead, he used the quote to emphasize that new e-discovery methods, namely random sampling and statistical analysis, can empower lawyers to know what they never did before. A technical way to know the known unknowns. For instance, a way to know the number of relevant documents that will be missed and not produced: the documents that elude retrieval.

As the opinion and this blog will explain, you can do that, know that, by using an Elusion random sample of the null-set. The statistical analysis of the sample transforms the unknown quantity to a known (subject to statistical probabilities and range). It allows lawyers to know, at least within a range, the number of relevant documents that have not been found. This is a very useful quality assurance method that relies on objective measurements to demonstrate success of your project, which here is information retrieval. This and other random sampling methods allow for the calculation of Recall, meaning the percent of total relevant documents found. This is another math-based, quality assurance tool in the field of information retrieval.

One of the main points Judge Johnston makes in his order is that lawyers should embrace this kind of technical knowledge, not shy away from it. As Tara Emory said in her article, Court Holds that Math Matters for eDiscovery Keyword Search:

Small Discovery Dispute in an Ocean of Cooperation

Judge Johnston was not asked to solve the deep mysteries of knowing and not knowing in City of Rockford. The parties came to him instead with an interesting, esoteric discovery dispute. They had agreed on a great number of things, for which the court profusely congratulated them.

The attorneys are commended for this cooperation, and their clients should appreciate their efforts in this regard. The Court certainly does. The litigation so far is a solid example that zealous advocacy is not necessarily incompatible with cooperation. The current issue before the Court is an example of that advocacy and cooperation. The parties have worked to develop a protocol for the production of ESI in this case, but have now reached an impasse as to one aspect of the protocol.

The parties disagreed on whether to include a document review quality assurance test in the protocol. The Plaintiffs wanted one and the Defendants did not. Too burdensome they said.

To be specific, the Plaintiffs wanted a test where the efficacy of any parties production would be tested by use of an Elusion type of Random Sample of the documents not produced. The Defendants opposed any specific test. Instead, they wanted the discovery protocol to say that if the receiving party had concerns about the adequacy of the producing party’s efforts, then they would have a conference to address the concerns.

Judge Johnston ruled for the plaintiff in this dispute and ordered a  random elusion sample to be taken after the defendant stopped work and completed production. In this case it was a good decision, but should not be routinely required in all matters.

The Stop Decision and Elusion Sample

One of the fundamental problems in any investigation is to know when you should stop the investigation because it is no longer worth the effort to carry on. When has a reasonable effort been completed? Ideally this happens after all of the important documents have already been found. At that point you should stop the effort and move on to a new project. Alternatively, perhaps you should keep on going and look for more? Should you stop or not?

In Legal Search we all this the “Stop Decision.” Should you conclude the investigation or continue further AI training rounds and other search. As explained in the e-Discovery Team TAR Course:

See: TAR Course: 15th Class – Step Seven – ZEN Quality Assurance Tests.

If you want to go deeper into this, then listen in on this TAR Course lecture on the Stop decision.

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Once a decision is made to Stop, then a well managed document review project will use different tools and metrics to verify that the Stop decision was correct. Judge Johnston in City of Rockford used one of my favorite tools, the Elusion random sample that I teach in the e-Discovery Team TAR Course. This type of random sample is called an Elusion sample.

Judge Johnston ordered an Elusion type random sample of the null set in City of Rockford. The sample would determine the range of relevant documents that likely eluded you. These are called False Negatives. Documents presumed Irrelevant and withheld that were in fact Relevant and should have been produced. The Elusion sample is designed to give you information on the total number of Relevant documents that were likely missed, unretrieved, unreviewed and not produced or logged. The fewer the number of False Negatives the better the Recall of True Positives. The goal is to find, to retrieve, all of the Relevant ESI in the collection.

Another way to say the same thing is to say that the goal is Zero False Negatives. You do not miss a single relevant file. Every file designated Irrelevant is in fact not relevant. They are all True Negatives. That would be Total Recall: “the Truth, the Whole Truth …” But that is very rare and some error, some False Negatives, are expected in every large information retrieval project. Some relevant documents will almost always be missed, so the goal is to make the False Negatives inconsequential and keep the Elusion rate low.

Here is how Judge Iain Johnston explained the random sample:

Plaintiffs propose a random sample of the null set. (The “null set” is the set of documents that are not returned as responsive by a search process, or that are identified as not relevant by a review process. See Maura R. Grossman & Gordon v. Cormack, The Grossman-Cormack Glossary of Technology-Assisted Review, 7 Fed. Cts. L. Rev. 1, 25 (2013). The null set can be used to determine “elusion,” which is the fraction of documents identified as non-relevant by a search or review effort that are, in fact, relevant. Elusion is estimated by taking a random sample of the null set and determining how many or what portion of documents are actually relevant. Id. at 15.) FN 2

Judge Johnston’s Footnote Two is interesting for two reasons. One, it attempts to calm lawyers who freak out when hearing anything having to do with math or statistics, much less information science and technology. Two, it does so with a reference to Fizbo the clown.

The Court pauses here for a moment to calm down litigators less familiar with ESI. (You know who you are.) In life, there are many things to be scared of, including, but not limited to, spiders, sharks, and clowns – definitely clowns , even Fizbo. ESI is not something to be scared of. The same is true for all the terms and jargon related to ESI. … So don’t freak out.

Accept on Zero Error for Hot Documents

Although this is not addressed in the court order, in my personal view, no False Negatives, iw – overlooked  documents – are acceptable when it comes to Highly Relevant documents. If even one document like that is found in the sample, one Highly Relevant Document, then the Elusion test has failed in my view. You must conclude that the Stop decision was wrong and training and document review must recommence. That is called an Accept on Zero Error test for any hot documents found. Of course my personal views on best practice here assume the use of AI ranking, and the parties in City of Rockford only used keyword search. Apparently they were not doing machine training at all.

The odds of finding False Negatives, assuming that only a few exist (very low prevalence) and the database is large, are very unlikely in a modest sized random sample. With very low prevalence of relevant ESI the test can be of limited effectiveness. That is an inherent problem with low prevalence and random sampling. That is why statistics have only limited effectiveness and should be considered part of a total quality control program. See Zero Error Numerics: ZEN. Math matters, but so too does good project management and communications.

The inherent problem with random sampling is that the only way to reduce the error interval is to increase the size of the sample. For instance, to decrease the margin of error to only 2% either way, a total error of 4%, a random sample size of around 2,400 documents is needed. Even though that narrows the error rate to 4%, there is still another error factor of the Confidence Level, here at 95%. Still, it is not worth the effort to review even more sample documents to reduce that to a 99% Level.

Random sampling has limitations in low prevalence datasets, which is typical in e-discovery, but still sampling can be very useful. Due to this rarity issue, and the care that producing parties always take to attain high Recall, any documents found in an Elusion random sample should be carefully studied to see if they are of any significance. We look very carefully at any new documents found that are of a kind not seen before. That is unusual. Typically  any relevant documents found by random sample of the elusion set are of a type that have been seen before, often many, many times before. These “same old, same old” type of documents are of no importance to the investigation at this point.

Most email related datasets are filled with duplicative, low value data. It is not exactly irrelevant noise, but it is not a helpful signal either. We do not care if we  get all of that kind of merely relevant data. What we really want are the Hot Docs, the high value Highly Relevant ESI, or at least Relevant and of a kind not seen before. That is why the Accept On Zero Error test is so important for Highly Relevant documents.

The Elusion Test in City of Rockford 

In City of Rockford Judge Johnston considered a discovery stipulation where the parties had agreed to use a typical keyword search protocol, but disagreed on a quality assurance protocol. Judge Johnston held:

With key word searching (as with any retrieval process), without doubt, relevant documents will be produced, and without doubt, some relevant documents will be missed and not produced. That is a known known. The known unknown is the number of the documents that will be missed and not produced.