Quote from bwolinsky:
I would expect any person looking into a trading system or considering investing in any advisory service to understand at least a little probability theory. Positive expectancy without an explanation of what it is and expecting people to accept that you have positive expectancy with your system is the nature of gurudom, yes, but it is a great disservice for those of us that actually know what it means to dismiss it as guru-like offhand. Positive expectancy assumes that after completing your backtest you know your probability of winning times the percentage win less the probability of losing times the percentage loss should be greater than zero. To shorten this calculation, you could just say that a system has positive expectancy.
Indeed I've seen it used as proof of a system maybe incorrectly, but it takes third party verification to validate any trading system's claim, and is the main reason I can ride on anybody that comes onto ET and immediately expects recognition for free. Common objections when you start questioning a system include that they saw it work well in other places, and I've done it this way for 10,20,30 years despite affordable trading only being available since around 1995.
After thinking on this awhile Iâve decided to respondâ¦
Bwolinsky
Please know I am not posting this to prove you wrong⦠I am posting this to show how a discretionary traderâs mindset is different â along with the views a discretionary trader holds regarding some of the more widely accepted views.
TheBestGuruEver
I beg your indulgence and forgiveness Sir
I would like to address positive expectancy from one discretionary traderâs standpoint â in other words âmyâ standpoint
MY DEFINITION â of Positive Expectancy;
I am âpositiveâ that I can âexpectâ my next trade â to either lose or make money
This is the only definition I acknowledge⦠(even though I remember someone on another thread being very adamant about how wrong I was when I posted my definition) so Iâll explain why â then yâall can decide if I am completely wrongâ¦
STARTING POINT
First allow me to state some absolute truths about the mkt/ tradingâ¦
Absolute truth #1 â Everything works till it doesnât
Absolute truth # 2 â The mkt is always changing/ evolving
Absolute truth #3 â Anything can and will happen in the mkt.
Btw â If anyone would like to dispute these absolute truths â please feel free to state your case⦠now onward
MY PERSPECTIVE
In order to be in total alignment with the above absolute truths⦠(which btw means I am trading with maximum efficiency and effectiveness.)
i I can not afford to be prejudiced or biased when entering a position.
ii I can not put anymore credence in one set up over another â else I am biased
iii I must always be willing to admit when a trade is not working and exit it â without hesitation or thinkingâ¦. Obviously for a loss â but a loss thatâs within my accepted % to lose.
ASIDE
Could I identify specific set ups, then wait on them to materialize â sure I could â but why limit myselfâ¦, that is unless I am unable to manage myselfâ¦
Oh and there is still no guarantee any given setup will work is there â reference the absolute truths
(No RN; but there is a higher probability isnât there⦠No there is not â that is an illusion folks - so humans can have some sense of knowing, some sense of control, some sense of creating certainty â out of a completely uncertain environment)
Give up control to gain control, accept uncertainty to create certainty â it will serve you well
TO CONTINUE
So if I were to enter a position with the mindset that this setup has a âpositive expectancyâ (as defined by the commonly accepted definition) and it fails â then I might hesitate / second guess my decision to exit â and remain in the position longer â thereby exposing myself to losing moreâ¦.
CONCLUSION
Should I ever fool myself into thinking/ believing/ knowing â âanyâ set up has x more % of working than another (it has a positive expectancy as define by the commonly accepted definition) â then I have just discounted all the above absolute truths, biased myself, minimized my trading effectiveness and efficiency, and more importantly â potentially set myself up for a blow out, or at best a loss of major proportion (a loss exceeding my accepted %).
Additionally I have also acknowledged that I do not trust myself â nor can I manage myself in a completely uncertain environment.
No Thank You
I have one definition â Itâs served me well over the years⦠Iâm sticking with it
NOW HAVING SAID THAT
I realize and acknowledge an automated trader is working under a different set of circumstances. I also acknowledge a positive expectancy (as defined by the commonly accepted definition) is an absolute must for an automated trader.
So I agree â and just as Bwolinsky has stated â a positive expectancy (as define by the commonly accepted definition) is important when using a system
However I (a discretionary trader) also maintain â the term positive expectancy (as define by the commonly accepted definition) â is a guru-ism â and utter BS
Regards
RN