Is your request related to a problem? Please describe.
I find it annoying when a new person joins our roster the attendance is 4% after the first raid. It defeats the purpose of using to see if people have a good attendance rate.

Describe the solution you'd like
A clear and concise description of what you want to happen.
When a person joins a roster they instantly get 100% attendance rate. The attendance rate should be base on the percentage of raids they've attended since they joined the roster up to the amount of raids in the given attendance period (X raids per week over Y weeks).
So if they've shown up to 3 raids out of 4 they've been able to join it should show 75% attendance and not 15% (assuming 2 raids a week over 10 weeks).

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.
Currently I need to save attendance in an external sheet instead.

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Any update on this? Would love it in Cataclysm

Not saying no but currently not yet under development

That seems like a good solution. I would love this!

I think this is doable to some extent. What I could do is change the attendance calculation from N raids / M weeks to N raids / minimum(M weeks, P weeks in roster). This way, if player is shorter time in the roster, his attendance will be calculated only over that period of time.