lost connectivity
Can this not be solved via technology?
passing the wrong trading parameters
What do you mean by this?
bad feed
Does this happen often?
temp computer problems
Again, can't technology be used to reduce this?
news/rumors
Could this not move the market in our favor just as easily?
not getting filled at the price the system thinks it got filled at
This is why we calculate in slippage. Do you knew a reason why this calculation is not sufficient?
tweaking your system (changes everything)
The point of mechanical trading is not to have to tweak. Am I wrong?
Your nerves and quality of life
The second reason I want to trade mechanical. Shouldn't this reduce stress? Do any of you feel that mechanical trading was more stressful?
My intention is not to criticize but to understand this once and for all. Thank you for your time.
Can this not be solved via technology?
These problems are caused by technology. Suffer through such a glitch and anything can happen. Does the BT take that into consideration? No, it does not.
Bad feed happens from time to time, and if you've got stops in place, they may get hit during intraday. This isn't factored into any BT, is it?
"news/rumors
Could this not move the market in our favor just as easily?"
It could. Doesn't mean it "evens out" in the end as if no long term consequence to your real trading results. But the BT doesn't filter news up or down.
"This is why we calculate in slippage. Do you knew a reason why this calculation is not sufficient?"
At best, it's a guess. Doesn't getting filled also have to do with the liquidity available for the price you're seeking?
"passing the wrong trading parameters
What do you mean by this?"
In real life trading, there could be times you send in an errored orders, such as sell when you meant buy, 200 shares when you meant 2000, limit when you meant stop...
"tweaking your system (changes everything)
The point of mechanical trading is not to have to tweak. Am I wrong?"
Your system will never need to be tuned? You'll never incorporate a newer idea into it? You'll never see to boost its performance? Your system will be perfect from day one? There's also no possibility of human error inadvertantly built into the system's logic? Of course, you'll tweak it now and then. But when you do, it's like starting over with a new system again for all intents and purposes.
"Your nerves and quality of life
The second reason I want to trade mechanical. Shouldn't this reduce stress? "
My oven does my baking mechanically, you could say, I can still get stressed if I burn the roast. Your computer doesn't sweat if your system has put you into 6 losing trades in a row. Your BT says that, historically, you won't suffer more than 6 bad trades in a row and remains cool about that. Will you? How will you feel when the 7th trade turns south? How will you feel when the system doesn't produce in real life going forward as it did in its simulated results? Calm? Nervous?
I guess my point is that BT is not a panacea. There's always more (to anything) that meets the eye, and humans have an escape mechanism that makes it even more difficult to deal honestly with these problems.
Hey, if you want to see how pathetic people can be about relying on BT results... hoo, hoo, boy oh boy, get a load of the posts on the Motley Fool's "Mechanical Investing" board. Those folks are losing about 50% per year for the last 3 years and still thinking it's Value Line's fault (when you realize that their systems depend mostly on VL ratings on year-to-date performances you can quickly undertsand why a forward going system built on past performance of stocks might be precarious at best, but to those diehards, they're still believeing in their systems, despite the evidence of continued massive losses to their portfolios).