Re: [amibroker] Re: Sell and Buy on different days, AmiBroker Email List Archive

On Fri, Jan 30, 2009 at 2:29 AM, Edward Pottasch <empottasch@xxxxxxxxx> wrote:

hi,

with an incomplete database or dataset I meant that many symbols have disappeared over the years through bankruptcies or takeovers. Best to get these in your database before doing portfolio backtests. Only a few providers have these symbols I believe. QP doesn't provide it.

Ed

----- Original Message -----

From: brian_z111

To: amibroker@xxxxxxxxxxxxxxx

Sent: Friday, January 30, 2009 10:04 AM

Subject: [amibroker] Re: Sell and Buy on different days

> In any case it could be traded if you organise your funds in such a
>way that all symbols in your list can be held simultaneously.

That isn't really practical and we can calculate very accurate
predictions, subject to variance and non-stationarity, before we risk
our money.

>there are a lot of additional problems that arise like an uncomplete
>database during testing

You can't get a good result out of a bad database.... just avoid
trades were you can't get the data you need.

>Not sure if a random selection on an extended list for testing
>purposes is reliable. Who knows in the practice you will find that
>the signals that come early during the trading session usually are
>loosers. This could be tested however using intraday data,

Yes it is reliable, in fact it is the only way that it can be done.

Returning to the example in my previous post:

a b c X d e f g h i
a b c Y d e f g h i
a b c Z d e f g h i

The XY & Z samples were produced by the same system (same rules) as
the a -> i samples, so they are part of the same series and share the
same profile (frequency distribution and probabilities).

If you have a list of trades for an EOD system and then want to find
out if the intraday time affects the result then you are ranking your
daily signals using an intraday factor and you have to add at least
one more trading rule to do that.

This is effectively a new system and it will produce its own trade
series , with it's own characteristics.

As always, if we do analyse the trade sample space, we have to make
sure we are left with enought samples to provide a valid sample.

NEW RULE == NEW SYSTEM == NEW AND UNIQUE TRADE SERIES

--- In amibroker@xxxxxxxxxxxxxxx, "Edward Pottasch" <empottasch@xxx>
wrote:
>
> In any case it could be traded if you organise your funds in such a
way that all symbols in your list can be held simultaneously. EOD
systems are tricky though since there are a lot of additional
problems that arise like an uncomplete database during testing (ENRN,
WCOM etc missing), no shorts available during trading. Not sure if a
random selection on an extended list for testing purposes is
reliable. Who knows in the practice you will find that the signals
that come early during the trading session usually are loosers. This
could be tested however using intraday data,
>
> regards, Ed
>
>
> ----- Original Message -----
> From: Mike
> To: amibroker@xxxxxxxxxxxxxxx
> Sent: Thursday, January 29, 2009 10:32 PM
> Subject: [amibroker] Re: Sell and Buy on different days
>
>
> Ha ha.
>
> Just goes to show how people can get tunnel vision sometimes.
Since I
> do a lot of custom backtester code, I immediately suggested
filtering
> at that level.
>
> But, your suggestion of a random value for PositionScore directly
> would be far easier and less prone to coding error.
>
> Mike
>
> --- In amibroker@xxxxxxxxxxxxxxx, "Edward Pottasch" <empottasch@>
> wrote:
> >
> > you are right on this Mike. Testing a system like this using a
> random positionscore is a good indication if it can be made into
a
> system that can be used in the practice. Andy has an idea that is
> tough to execute but not impossible in my opinion,
> >
> > regards, Ed
> >
> >
> >
> >
> >
> > ----- Original Message -----
> > From: Mike
> > To: amibroker@xxxxxxxxxxxxxxx
> > Sent: Thursday, January 29, 2009 8:37 PM
> > Subject: [amibroker] Re: Sell and Buy on different days
> >
> >
> > Andy,
> >
> > Use caution when backtesting EOD strategies where there are
more
> > signals than there are funds or positions to be filled;
> >
> > If your strategy is to buy OCA, what logic are you putting in
> place to
> > determine which symbol to buy when multiple symbols hit your
limit
> > order on the same bar?
> >
> > Since you are using EOD data, you have no idea which symbol
would
> have
> > hit the limit order first. You only know that x of y symbols
hit
> the
> > limit order on that day.
> >
> > AmiBroker will just select the first in the list
(alphabetically?
> ). As
> > such, your backtest results will be heavily biased in favor of
> that
> > ordering and will not reflect live trading results.
> >
> > Generally, PositionScore can be used to influence ordering.
But,
> an
> > OCA approach by definition does not follow PositionScore.
> >
> > So, you might want to modify your custom backtester code to
> randomly
> > select from the available signals and set the remaining ones to
> > PosSize 0 in order to override the default prioritization. Then
> run
> > your backtest many times and take the average of the results as
a
> best
> > guess estimate (i.e. Monte Carlo Permutations)
> >
> > Mike
> >
> > --- In amibroker@xxxxxxxxxxxxxxx, Andrew Senft <senft@> wrote:
> > >
> > > Hey Ed,
> > >
> > > Thank you so much for the code on the Amibroker Yahoo group
> board!
> > It
> > > seems to be working from what I've seen so far. I'm doing an
> > > optimization on that particular code (your first code) right
> now.
> > >
> > > The second code (the one from your email) didn't work. That
is,
> > there
> > > were sales of one stock and buy of another stock on the same
> day.
> > Not
> > > sure what your code was doing but it gave a lot bigger
profits
> using
> > the
> > > backtester. Could you comment on this please?
> > >
> > > Mind you that this is my first attempt to writing code for
any
> stock
> > > type software. I'm still using the 30 day free trial of the
> > Amibroker
> > > software but I think that I'm getting closer as I'm chugging
> along.
> > >
> > > My agenda is to use this on a basket of ETF's. Perhaps 10 to
20
> > or
> > > so. Not sure how many I need since the 30 day trail backtests
up
> > to a
> > > basket of 5 stocks. My idea is to place the possible stock
> trades
> > > using the whole basket of ETF stocks at night for the next
> trading
> > > session. I have an IB account so I figure I could use an OCA
> limit
> > > order. Basically whenever a trade gets hit first (meets the
> limit
> > price
> > > level), it trades. The other possible trades all get canceled
> right
> > > away. So one trade actually goes through for the day.
> > >
> > > BTW, I like ETF's because the drawdowns are not as scary....
> okay,
> > > usually not as scary. Ha! I've been backtesting with:
> > >
> > > QQQQ, DIA, SPY, MDY, IWM
> > >
> > > Thank you again!
> > >
> > > Andy
> > >
> > > Edward Pottasch wrote:
> > > >
> > > > Andy,
> > > >
> > > > I have sent an alternative solution to your private Email.
Let
> me
> > know
> > > > if you received it.
> > > >
> > > > Ed
> > > >
> > > >
> > > >
> > > > ----- Original Message -----
> > > > *From:* Andy <mailto:senft@>
> > > > *To:* amibroker@xxxxxxxxxxxxxxx
> > <mailto:amibroker@xxxxxxxxxxxxxxx>
> > > > *Sent:* Thursday, January 29, 2009 12:40 PM
> > > > *Subject:* [amibroker] Re: Sell and Buy on different days
> > > >
> > > > This is got to be a very simple task but unfortunately
> > AmiBroker told
> > > > me that I would have to write Backtester Interface code for
> > this. I'm
> > > > sure this has been done a million times. Anyone have sample
> > code?
> > > > I'm using EOD data to trade one stock at a time from a
basket
> > of
> > > > stocks. The problem is that a selling of a stock can occur
on
> > the
> > > > same day as a buy of *another* stock. Of course the problem
is
> > that
> > > > the sell trade can occur after the buy trade.
> > > >
> > > > --- In amibroker@xxxxxxxxxxxxxxx
> > > > <mailto:amibroker%40yahoogroups.com>, "Andy" <senft@> wrote:
> > > > >
> > > > > How do I fix the below code so it doesn't buy a different
> > stock on a
> > > > > sell day?
> > > > >
> > > > > --------------------------------------------------------
> > > > > // Backtester Options
> > > > > SetOption("MaxOpenPositions", 1 );
> > > > > SetOption("AllowSameBarExit", False);
> > > > >
> > > > > // Optimization numbers
> > > > > BuyPeriod = Optimize("BuyPeriod",16,10,20,2);
> > > > > BuyFactor = Optimize("BuyFactor",1.2,0.5,1.5,.1);
> > > > > SellPeriod = Optimize("SellPeriod",20,10,20,2);
> > > > > SellFactor = Optimize("SellFactor",0.8,0.5,1.5,.1);
> > > > >
> > > > > // ATR formulas
> > > > > TodaysBuyTarget = High - BuyFactor * ATR(BuyPeriod);
> > > > > YesterdaysBuyTarget = Ref(High,-1) - BuyFactor *
> > > > Ref(ATR(BuyPeriod),-1);
> > > > > YesterdaysSellTarget = Ref(Low,-1) + SellFactor *
> > > > Ref(ATR(SellPeriod),-1);
> > > > >
> > > > > // Buy/Sell signals and prices
> > > > > Buy = YesterdaysBuyTarget > Low;
> > > > > BuyPrice = IIf(YesterdaysBuyTarget > Open, Open,
> > > > YesterdaysBuyTarget);
> > > > > Sell = YesterdaysSellTarget < High;
> > > > > SellPrice = IIf(YesterdaysSellTarget < Open, Open,
> > > > YesterdaysSellTarget);
> > > > > Buy = ExRem(Buy,Sell);
> > > > > Sell = ExRem(Sell,Buy);
> > > > >
> > > >
> > > >
> > > > ----------------------------------------------------------
> > ------
> > > >
> > > >
> > > > No virus found in this incoming message.
> > > > Checked by AVG - http://www.avg.com
> > > > Version: 8.0.176 / Virus Database: 270.10.15/1921 - Release
> Date:
> > 1/28/2009 6:37 AM
> > > >
> > > >
> > >
> >
>