current daily:
200 new joins
400 recuring
3 chargebacks (@ 0.5% of 600)
Assuming the site is stable at this point,
where new joins balance drop outs, there is:
app. 1 2/3% turnover/day, or 98.3% expected daily shrinkage w/o new joins
Using: <B>#recurs * (daily shrinkage)^#days</B> (where #recurs = 400, daily shrinkage = .983, #days = 30)
400 * (0.983)^30 = 400 * 0.597868311 =~
app. 239 recurs/day after one month
BUT, due to the previous month's activity, still with 3 chargebacks daily, so:
3/239 = 1.26% Chargeback Ratio after 30 days w/o new joins.
And it's worse after 60 days; if there are still 3 CB's/day- you'd have a 1.52% Chargeback Ratio.
The way I see it, you either need to find a rampdown percentage of new joins that keeps you around a 0.75% CB ratio (easily computed if the CB lag time is known) or work out a deal ahead of time with your processor on the expected.
Or, of course, just sell it to KK and let her deal with it.
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