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What is the grade-averaging algorithm?!


Robert Hall · · North Conway, NH · Joined Aug 2013 · Points: 16,338

Look at the MtnPrjct "statistics" for about any climb and you'll probably find something like this:

100 climbers "ticked" it, of these..

about 10-20 bothered to give it a "star" rating but did not voice their opinion of the grade,.... of the 10-20 who "star-ed" it,

about half (5 or 10) also gave it a suggested grade rating, and

80-90% ( 4 of 5,  to about 9 of 10) of those stayed with the climb's "given" grade rating.

So whatever the algorithm is, it's unlikely the grade will change.    
 

Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,995
Robert Hall wrote: Look at the MtnPrjct "statistics" for about any climb and you'll probably find something like this:

100 climbers "ticked" it, of these..

about 10-20 bothered to give it a "star" rating but did not voice their opinion of the grade,.... of the 10-20 who "star-ed" it,

about half (5 or 10) also gave it a suggested grade rating, and

80-90% ( 4 of 5,  to about 9 of 10) of those stayed with the climb's "given" grade rating.

So whatever the algorithm is, it's unlikely the grade will change.    
 

Certainly not based on the info you've posted.

I think the issue is more along the lines of, when someone enters a route in the database, and one person rates it different, then the rating changes.
Robert Hall · · North Conway, NH · Joined Aug 2013 · Points: 16,338

From what Nick has said/told us it would have to be a BIG difference.  Ah.. but wait, didn't he say it actually returned the MEAN (not the AVERAGE); if so then one different could affect it. ??

Nick...what's the story here?

Nick Wilder · · Boulder, CO · Joined Jan 2005 · Points: 3,436

We use the MEDIAN grade as the consensus.  So when there are very few submissions (they start with one, from the OP), the consensus is very sensitive.  As the route gets more ratings, an outlying rating will have no affect.

Guideline #1: Don't be a jerk.

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