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Irish Chess Union Rating Conversion?

Posted: Sun Oct 13, 2019 2:38 pm
by Steve Lovell
Hi there,

I've had an Irish family trio enter my tournament. Two of the three have FIDE ratings in addition to their Irish Chess Union rating, but nothing for the third player (who in ICU rating terms is the middle of the three). Has anyone much experience with the ICU ratings and how they should be handled for calculating an ECF equivalent?

Using the FIDE -> ECF formula but starting from an ICU rating instead seems wrong as while the ICU rating is elo style, that doesn't guarantee equivalence (compare USCF).

Are there any reasonably trustworthy conversions available?

Cheers,

Steve

Re: Irish Chess Union Rating Conversion?

Posted: Sun Oct 13, 2019 2:47 pm
by IM Jack Rudd
I suggest you do a linear interpolation from the FIDE and ICU ratings you have to work out what FIDE rating that player would probably have if they had one, and then convert from that.

Re: Irish Chess Union Rating Conversion?

Posted: Mon Oct 14, 2019 9:22 am
by Steve Lovell
Cheers Jack. That's exactly what I've done. The resulting formula was (approximately) ECF = (ICU/10) -18.

I'd have done this with a bit more confidence except that the result is quite near a section grade boundary (just below).

If I get some time after our event, I may make an informal study of the subject to aid anyone else who may find themselves in the same situation.

Re: Irish Chess Union Rating Conversion?

Posted: Tue Oct 15, 2019 3:34 pm
by Ian Jamieson
By coincidence this formula (or the equivalent ICU=ECF*10+180) is the same formula Chess Scotland use for converting ECF grades.

Re: Irish Chess Union Rating Conversion?

Posted: Tue Oct 15, 2019 5:18 pm
by Roger de Coverly
Ian Jamieson wrote: ↑
Tue Oct 15, 2019 3:34 pm
By coincidence this formula (or the equivalent ICU=ECF*10+180) is the same formula Chess Scotland use for converting ECF grades.
It's probably not a coincidence as a few years ago, the ECF moved the centre of its grading list from around the 115-120 level to around the 140 level. So modestly graded Irish or Scottish players taking part in English events found themselves 20 to 25 ECF points higher.