This blog post was written in 2014, when I still naively hoped that the myriad problems with cryptocurrency might still be solved. I am now somewhat embarrassed to have written this in the first place, but will leave the post up for historical reasons. (Quite a number of medical journal articles link here now, for better or for worse.)
While the following methods are valid as far as they go, I absolutely DO NOT recommend actually using them to timestamp research protocols. In fact, I recommend that you never use a blockchain for anything, ever.
The gerrymandering of endpoints or analytic strategies in medical research is a serious ethical issue. “Fishing expeditions” for statistically significant relationships among trial data or meta-analytic samples can confound proper inference by statistical multiplicity. This may undermine the validity of research findings, and even threaten a favourable balance of patient risk and benefit in certain clinical trials. “Changing the goalposts” for a clinical trial or a meta-analysis when a desired endpoint is not reached is another troubling example of a potential scientific fraud that is possible when endpoints are not specified in advance.
Choosing endpoints to be measured and analyses to be performed in advance of conducting a study is a hallmark of good research practice. However, if a protocol is published on an author’s own web site, it is trivial for an author to retroactively alter her own “pre-specified” goals to align with the objectives pursued in the final publication. Even a researcher who is acting in good faith may find it less than compelling to tell her readers that endpoints were pre-specified, with only her word as a guarantee.
Advising a researcher to publish her protocol in an independent venue such as a journal or a clinical trial registry in advance of conducting research does not solve this problem, and even creates some new ones. Publishing a methods paper is a lengthy and costly process with no guarantee of success—it may not be possible to find a journal interested in publishing your protocol.
Pre-specifying endpoints in a clinical trial registry may be feasible for clinical trials, but these registries are not open to meta-analytic projects. Further, clinical trial registry entries may be changed, and it is much more difficult (although still possible) to download previous versions of trial registries than it is to retrieve the current one. For example, there is still no way to automate downloading of XML-formatted historical trial data from www.clinicaltrials.gov in the same way that the current version of trial data can be automatically downloaded and processed. Burying clinical trial data in the “history” of a registry is not a difficult task.
Publishing analyses to be performed prior to executing the research itself potentially sets up a researcher to have her project “scooped” by a faster or better-funded rival research group who finds her question interesting.
Using the bitcoin blockchain to prove a document’s existence at a certain time
Bitcoin uses a distributed, permanent, timestamped, public ledger of all transactions (called a “blockchain”) to establish which addresses have been credited with how many bitcoins. The blockchain indirectly provides a method for establishing the existence of a document at particular time that can be independently verified by any interested party, without relying on a medical researcher’s moral character or the authority (or longevity) of a central registry. Even in the case that the NIH’s servers were destroyed by a natural disaster, if there were any full bitcoin nodes left running in the world, the method described below could be used to confirm that a paper’s analytic method was established at the time the authors claim.
- Prepare a document containing the protocol, including explicitly pre-specified endpoints and all prospectively planned analyses. I recommend using a non-proprietary document format (e.g. an unformatted text file or a LaTeX source file).
- Calculate the document’s SHA256 digest and convert it to a bitcoin private key.
- Import this private key into a bitcoin wallet, and send an arbitrary amount of bitcoin to its corresponding public address. After the transaction is complete, I recommend emptying the bitcoin from that address to another address that only you control, as anyone given the document prepared in (1) will have the ability to generate the private key and spend the funds you just sent to it.
The incorporation into the blockchain of the first transaction using the address generated from the SHA256 digest of the document provides an undeniably timestamped record that the research protocol prepared in (1) is at least as old as the transaction in question. Care must be taken not to accidentally modify the protocol after this point, since only an exact copy of the original protocol will generate an identical SHA256 digest. Even the alteration of a single character will make the document fail an authentication test.
To prove a document’s existence at a certain point in time, a researcher need only provide the document in question. Any computer would be able to calculate its SHA256 digest and convert to a private key with its corresponding public address. Anyone can search for transactions on the blockchain that involve this address, and check the date when the transaction happened, proving that the document must have existed at least as early as that date.
This strategy would prevent a researcher from retroactively changing an endpoint or adding / excluding analyses after seeing the results of her study. It is simple, economical, trustless, non-proprietary, independently verifiable, and provides no opportunity for other researchers to steal the methods or goals of a project before its completion.
Unfortunately, this method would not prevent a malicious team of researchers from preparing multiple such documents in advance, in anticipation of a need to defraud the medical research establishment. To be clear, under a system as described above, retroactively changing endpoints would no longer be a question of simply deleting a paragraph in a Word document or in a trial registry. This level of dishonesty would require planning in advance (in some cases months or years), detailed anticipation of multiple contingencies, and in many cases, the cooperation of multiple members of a research team. At that point, it would probably be easier to just fake the numbers than it would be to have a folder full of blockchain-timestamped protocols with different endpoints, ready in case the endpoints need to be changed.
Further, keeping a folder of blockchain-timestamped protocols would be a very risky pursuit—all it would take is a single honest researcher in the lab to find those protocols, and she would have a permanent, undeniable and independently verifiable proof of the scientific fraud.
Fraud in scientific methods erodes confidence in the medical research establishment, which is essential to it performing its function—generating new scientific knowledge, and cases where pre-specified endpoints are retroactively changed casts doubt on the rest of medical research. A method by which anyone can verify the existence of a particular detailed protocol prior to research would lend support to the credibility of medical research, and be one less thing about which researchers have to say, “trust me.”