Talk:Profitability/@comment-4192477-20110723212956/@comment-4045164-20110724174007

I don't know what it is, but I don't know if the formula of Adi is correct. Is it the percentage or something else (I'm not a mathematican, where does one of us go wrong).

When we look at the numbers of "times income collected" and "times repaired" of many users, we see 14 times income collected, 1 time repaired.

If we take: income=$ 1000, repair=$ 2000, income time=2 hours, repair time=1 hour.

So on average we have 14 * 1000 income and 1 * 2000 repair in a total time of 29 hours

In a formula: (14*1000 - 2000) / (14*2 + 1) = 414

Adi uses the percenatge in his formula:

((1-p)*income - p*repair) / ((1-p)*IncHours + p*RepHours)

with p is the repair chance, in our case 1/14 = 0.0714285. This gives:

(0.9285715*1000 - 0.0714285*2000) / (0.9285715*2 + 0.0714285*1) = 407

In case the ratio is exact 14 * income, 1 * repair, the result is 414, not 407.

I know the ratio is not exact 14 - 1, it's just an example, but by that example I doubt about the correctness of the formula.