A Starting Point

I think you will find this exremely informative and any comments you would like to leave at the bottom, are welcome.

So, a few people asked about calculating losing runs, lots of replies but this reply goes a long way (and I mean... a long way) to help some of you out, once again Dave from London wrote...

Hi Paul,
Sure thing. The Longest Losing Run is calculated with the formula:
Log(No. Bets)/- Log(1 - SR)*
Where:
*Log *is the logarithm to base 10 or base e.
*No. Bets* is the number of bets that we intend to place.
*SR* is the Strike Rate of the selection system (in decimal format).
In Excel this can be added to a cell using:
=LN(A1)/(-LN(1-B1))

Where A1 is a cell containing your Number of Bets and B1 is a cell
containing your Strike Rate in decimal format (e.g. 0.34 for 34% Strike Rate)
As a working example:
A1 contains "306" bets
B1 contains "0.34" Strike Rate
therefore the theoretical Longest Losing Run for that system would be 13.62
In actuality I can tell you it's hit an LLR of 10 so far but ordinarily at
some point in it's life it will hit the top end of the LLR.
If Excel is a pain or people would rather just have a simple table here you
go:
Strike Rate (%) Max. Losing Run
5 135
10 66
15 43
20 31
25 24
30 19
35 16
40 14
45 12
50 10
55 9
60 8
65 7
70 6
75 5
80 4
85 4
90 3
95 2
Being able to calculate the theoretical Longest Losing Run in my systems is
one of the best things I've ever done with racing as it always stops me
from over-reaching with my stakes.
NOTE: Just because your theoretical LLR is covered bear in mind that you
could still hit a few shorter LLR's with only a single winner in between
them so I personally still only stake to my bank divided by the 3 times the
LLR just in case.
Have fun,
Dave

Then Dave followed that up with...

Hi again Paul,
Using SaW with a Dutching system makes complete sense:
- Dutching averages the odds of all the selected runners.
- Averaging the odds lowers them overall.
- Lowering the odds increases the Strike Rate for the system.
- Increasing the Strike Rate means you'll hit your winner quicker.
- Increasing the Strike Rate also shortens the Longest Losing Run.
- Shortening the Longest Losing Run means you'll be less likely to come
unstuck if staking too much.
I can absolutely see the appeal of Stopping At A Winner when Dutching.
I'd be interested to see what would have occurred if the Dutching system
was run without the SaW applied (not in the slightest bit saying it would
be better by the way, just curious) :)

Dutching has always worried me in the past because we're effectively
backing a single runner with the average odds of all our Dutched runners
and so we're also backing a single runner with the average Value for those
selections. Getting a value bet on a single horse for a long term profit is
difficult so the more runners in a race we try to get value on the less
likely we are to get it and when we do it will be lower value.

Assuming from an optimistic perspective that we got 10% value on 2 of those
and 5% value on the other two (in reality I don't think it's possible to
get that much value over that many runners) we're averaging 7.5% value
rather than backing a single runner with 10% value. We might not hit
winners as often because our average odds are higher but as our value is
also higher when we do hit the winner we'll win more and increase the bank
quicker.

As you've said on a few occasions there's no right or wrong in this game,
just what each player is happy to accept for their own personal systems.
Ta,
Dave (W if that helps)
 

Well...Thank you Dave.

I'm sure there's lots to be taken out of that wealth of information.