Are opening prices before 2004 accurate?
Here is a recent post with Marco’s comment on the subject that you can interpret yourself: Opening prices redux - #3 by marco
There are other posts you can search.
And an unanswered question about splits. @marco P123’s engagement in the forum seems random at best. Certainly not geared toward answering questions or responding to issues for machine learners using the API and or DataMiner.
When is the AI/ML release? There might be more questions than simple ones about the quality of data then.
It was not that long ago that Future%ChgD(5) had look ahead-bias and it took a lot for that to be noticed and addressed. Opening prices and splits are potential problems that some did not even know to ask about (including me which splits and others on opening prices) and there are remaining unanswered in the forum.
To the best of my knowledge there was a lag introduced into the analysts’ data (after a few years) to addresss the look-ahead bias that FactSet itself addresses here: Point-in-Time Database vs. Traditional FE Database
But one can no longer get answers on this in the forum and I am not aware that there is anything about this on P123’s site.
All machine learning tests, including holdout test sets come with an asterisk: “Assumes there was no significant look-ahead basis or another unknown problem with he data.” I think I can point to some people who have at least stopped posting after having unanswered questions about the data quality. Maybe they are still with P123 and just learned that it doesn’t do much good to ask but maybe not. It remains difficult for an individual to quantitate the problems with the data—assuming she is even aware of alll for the potential problems.
I do think machine learners notice this if you want a robust, dedicated machine learingingfollowing. Quantopian understood this and had extensive documentation on what it did to address issues with the data (they used FactSet also).
P123 still has the potential to capture some of the Quantopian market. There is still a vacuum—for now. @marco, P123 should address the split question today (along with opening prices) if it is serious about filling that vacuum.
Edit for Below: Thank you Jonpaul for answering some of the questions about P123 data! As well as raising the new question as to how exactly future%cahg_d(5) is calculated.