Hi Novice,
This is the way I do it .

Net Profit calculation
(also known as P/L)
Write down the total Gross Returns (this means the total Ret including the bet amnt before net profit is calculated) e.g. $240

Write down the total Outlays e.g. $200

Take one away from the other e.g. $240-200= +$40 Net Profit & that will be ones P/L (profit /loss)

POT calculation.
Divide the above Net Profit figure into the total Outlay figure
e.g. +40/200 = 20% POT (profit on turnover)

If it was a Loss say -10/200 = -5% LOT (loss on turnover)

It makes it easy to compare statergys once everything is converted to percentages.

SR calculation
Divide the number of winners by the total number of bets
e.g. 50 wins / 167 bets = 30% SR (strike rate)

ROI calculation
(Gross Return on Investment) in this case it is the Gross Ret
e.g. $240 / 200 = 120% ROI (before net is caculated).
Take away 120% -100% = 20% POT (net profit)

Personally I dont use ROI calculation, I have shown it here because you requested it.

I use SR percentages & POT percentages only.

Average Dividend is caculated by dividing the No. of winners into the Gross $ Ret amount e.g. 50 wins / $240 = $4.80 av div.

Once you have worked out your SR, I will be able to give you an approximation of what the longest run of outs one should encounter at some stage & it will happen , no matter how good a plan is.
We need to know this, so we can create a stratergy in advance so when it happens , we wont be caught off guard.

Cheers.

__________________
Cheers.