Lumifer comments on Stupid Questions December 2014 - Less Wrong

16 Post author: Gondolinian 08 December 2014 03:39PM

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Comment author: wadavis 12 December 2014 04:30:35PM 1 point [-]

We have different goals. I want to my rating to reflect the items relative position in its group, you want a rating to reflect the items value independent of the group.

Is this accurate?

Comment author: Lumifer 12 December 2014 04:56:48PM *  2 points [-]

Doesn't seem so. If you rate by quintiles your rating effectively indicates the rank of the bucket to which the thing-being-rated belongs. This reflects "the item's relative position in its group".

If you want your rating to reflect not a rank but something external, you can set up a variety of systems, but I would expect that for max information your rating would have to point a quintile of that external measure of the "value independent of the group".

Comment author: wadavis 12 December 2014 06:47:30PM 0 points [-]

Trying to stab at the heart of the issue: I want the distribution of the ratings to follow the distribution of the rated because when looking at the group this provides an additional piece of information.

Comment author: Lumifer 12 December 2014 08:31:51PM 4 points [-]

Well, at this point the issue becomes who's looking at your rating. This "additional piece of information" exists only for people who have a sufficiently large sample of your previous ratings so they understand where the latest rating fits in the overall shape of all your ratings.

Consider this example: I come up to you and ask "So, how was the movie?". You answer "I give it a 6 out of 10". Fine. I have some vague idea of what you mean. Now we wave a magic wand and bifurcate reality.

In branch 1 you then add "The distribution of my ratings follows the distribution of movie quality, savvy?" and let's say I'm sufficiently statistically savvy to understand that. But... does it help me? I don't know the distribution of movie quality. it's probably bell-shaped, maybe, but not quite normal if only because it has to be bounded, I have no idea if its skewed, etc.

In branch 2 you then add "The rating of 6 means I rate the movie to be in the sixth decile". Ah, that's much better. I now know that out of 10 movies that you've seen five were probably worse and three were probably better. That, to me, is a more useful piece of information.

Comment author: wadavis 15 December 2014 03:35:13PM 0 points [-]

I understand and concede to the better logic. This provides greater insight on why the original attempt to use these ratings failed.