Achievement Rarity Calculation Discussion

In response to discussion on the Bombcast of calculation regarding achievement rarity - among other things - I would argue that the calculation would benefit from taking into account the number of users who have achievements in the game containing the achievement in question.

I think at the moment, the rarity calculation is applied wholesale across all people who have the game on their profile. However, this skews the rarity representation particularly where Xbox Live Arcade games are concerned, in which many people played the trial, but didn't buy the game and will always have zero achievements in that game. To this end, using only people who have achievements in any given game would give a better representation, since this is pretty much the only way to guarantee a person actually has that game.

So for example:

x = #peopleWhoHaveAchievement
y = #peopleWhoHaveAchievementsInGame
z = achievementPercentage

(x / y) * 100 = z

Then you apply your ranges for percentages that make an achievement rare / uncommon / common.

The current system is certainly something similar to this. I just can't believe so many people bought Rez and then never played it!

Thanks

Uh... how do you think they do it? Snide (I think) posted the percentages somewhere. I don't remember them exactly, but they use a formula just like that. :-S

You're suggesting exactly what the system is. It's a rare achievement if less than 10% of people who have the game have the achievement. It's an uncommon achievement if less than 30% of people who have the game have the achievement.

And yet...

Games that are unplayed in the majority have almost 100% rare achievements, which appears to be a calculation based on all people, rather than people who have achievements in that game.

There has been a tweet regarding awareness of rarity issues, so I suspect they have noticed this problem.

Thank you for your time, patience and sarcasm. Oh, and for not understanding the problem addressed.

I have a somewhat on topic question, With the rarer achievements they tend to be ones that are listed as secret normally on the xbox achievements list, is there any way to have them show their real name and/or description? Its rather annoying not knowing what my rare/uncommon achievements are because they are all listed as secret.

Ah I figured as much, sucks though. Thanks for the info