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tech/a said:Ah
Knobby similar to the 50/50/90 rule.
If you have a 50% chance of making the correct decision there is a 90% chance you'll get it wrong!
I always allow for more drawdown than was given in backtesting and if my loosing trades in a row is double those given in backtesting I consider my system to over opertermised and not robust enough and time to develop a better system.
tech/a said:Ah
Knobby similar to the 50/50/90 rule.
If you have a 50% chance of making the correct decision there is a 90% chance you'll get it wrong!
tech/a said:Julia.
Nothing scientific here.Some other character came up with it and I liked it so much I claimed at as my own! Every time I go into a street I'll turn the wrong way 90% of the time and I'll be most others do to.
90% of the time I'll say the wrong thing according to the missus.
strw23 said:I also chat on another forum and a lot of people there who are being troubled by their emotions (selling early to take profit or quitting a system before its had a decent run) normally post what they're about to do. They then get about ten replies telling them not do it and why the should be following their system and that is often all the reasurance they need to remind them to stay on track.
happytrader said:Don't hold yourself up for judgement and the issues of others by telling them what you are doing.
tech/a said:Scott.
Defeats the purpose of backtesting.
If a mechanical methodology trades beyond its blue print to ANY extent let alone by large degrees,then its not even remotely close to its tested results.
If your getting drawdown beyond that found in testing then chances are your system hasnt enough data or the testing you are using doesnt have the capacity to test large data bases or multiple timeframes or portfolios.
Are you trading stock?
Or Futures?
What software do you use for testing?
Have you tested using MonteCarlo analysis.
Rather than take away emotion,results as you have described would heighten in security and deminish trust!
Why give any allowence at all!
Strw23 said:One thing I would like to incorperate into my testing is that if my system throws up three trades and I only have the equity to take two I want a rating system built into my rules so it tells me which two to take to make it completely mechanical. Metastock cant do this but I am told it can be done with WealthLab.
Back testing does not give a 100% accurate measure of a trading system’s properties.
RichKid said:'Given a 50/50 chance, you'll get it wrong 90 of the time.'
Tech, I'm interested in the concept too, so if you have a 50% chance of getting the right outcome YOU get it wrong 90% of the time. Of course we only know it's wrong in hindsight.
So the initial odds don't change (provided there are only two possible results) and to alter the outcome (for your benefit during future ventures onto the streets of Adelaide!) we'll have to know what your initial judgement was based on. Has anyone discussed this in a meaningful mathematical way over the years that you have mentioned it? Has piqued my interest since I'm still looking at probability vis a vis trading and expectancy. I don't think there's much in it, ie just a phrase, but some one wiser may think otherwise.
Julia said:Tech
Your response to Richkid's post above was "Settle down, it's a joke".
That's why I asked the question as the "Rule" didn't make a lot of sense to me. e.g. I don't think that, when faced with a 50/50 choice, I - or for that matter, most people - would get it wrong 90% of the time.
You will probably consider that I'm being stuffy and pedantic here, and perhaps I am, but I'm always conscious of new investors who will take anything they read which is written by someone who obviously knows what they are talking about - and you know you are thus classified - as being TRUTH. They may not have the confidence to question what you mean so will puzzle over it and wonder what they're missing or doing wrong.
This is not intended to "get at you" at all. Rather to ensure that all the useful and constructive info you post which people find so helpful doesn't get confused with the bits that you regard as jokes.
Cheers
Julia
Knobby22 said:The point Tech is making, is that given a 50/50 chance and given you are trading on spur of the moment judgements with emotions running, adrenaline flowing etc. you are more likely to get it wrong than by instead tossing a coin. The 50/50 is the coin, the 90% is the chance you CHOSE wrongly.
If anyone thought about it then they would see that the 90% chance is just a figure plucked out of air as everyone is different in any case and usually improve their decisions over time.
I didn't take it very seriously but there is TRUTH in it.
..and yes I agree with you that your argument is pendantic. Come on, people should be thinking about information, not just accepting every bit of info as gospel. Otherwise it's garbage in garbage out.
Even the best info is not 100% true 100% of the time. When we stop questioning we are allowing our minds to atrophy. I hear many people quoting books that are basically a lot of crap but I don't bother with questioning them as I would be doing it all day. This thread has quite a lot of it.
Sorry to be so black and white. Please do not take offence.
This forum is hardly an academic study in human behaviour.
Regards
Knob
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