Curious Prime Grid dump in secondpass

[VJS]

I was just curious about prime grids dump of 9500 tests totaling exactly 1M points.

Is this real or a stats glitch, also I was curious as to why Prime grid was doing double checks? Is it simply reissued tests from users who were late with tests or are they getting assigned doubles.

[mdettweiler]

Originally Posted by VJS

I was just curious about prime grids dump of 9500 tests totaling exactly 1M points.

Is this real or a stats glitch, also I was curious as to why Prime grid was doing double checks? Is it simply reissued tests from users who were late with tests or are they getting assigned doubles.

PrimeGrid automatically does doublechecks on all its numbers--i.e. they tell their BOINC server software that the workunits have both a "quorum" and "initial replication" of 2, which means that the workunit it sent out twice from the start, and two matching results must be returned before any credit is assigned to either user. This helps to practically eliminate the problem of bad residuals, which is quite widespread in BOINC projects due to unwitting owners who just let their machines crunch away and never bother to check on them.

[themerrill]

are we going to double check the result that PrimeGrid sends us on our own double check server? Or do we assume they are right because of the required quorum they have?

[mdettweiler]

Originally Posted by themerrill

are we going to double check the result that PrimeGrid sends us on our own double check server? Or do we assume they are right because of the required quorum they have?

Well, I would think that it's safe to assume that once you have two separate, matching residuals for the same number, the chances that the result is inaccurate is quite miniscule indeed. Not to mention that PrimeGrid is, in effect, doing the exact same thing that PSP is doing in its own doublechecking--namely, considering a k/n pair verified when at least two matching residuals are had--the only difference being that PrimeGrid is doing both its firstpass and doublecheck tests at the same time, rather than years apart.

[ltd]

We will not rerun any of the primegrid residues as with the quorum of 2 they test a pair until there are two matching residues.

And i have checked the points. It was really pure luck that the 9500 tests done by primegrid gave 1000000.00000 points.