The perfect moving average

Discussion in 'Technical Analysis' started by aphexcoil, Sep 6, 2002.

  1. aphie,

    i think you may have overlooked the above statement. i think jem has made a good point.

    don't you really just need a setup that allows big room in your direction if you're right..and then from that, just manage the trade?
    #51     Sep 9, 2002
  2. Gordon,

    To tell you the honest truth, I don't know where I am going with all of this, but when I get there, I think I might know where I am when that time comes.

    Does that make any sense?

    In other words -- I'm walking around a pitch black room trying to find the light switch and stubbing my little toe in the process.

    He brought up some very good points. It has been said before in here (ET) that there are two methodologies to successful trading. One is a high percentage of winners with low levels of profit -- and the other is a low percentage of winners with high profit levels per winner.

    This system, as it stands right now, is more geared towards swift, quick momentum trades that pull a point or two points with a success rate of around 60-70%. I'm assuming that I can do this type of trading up to maybe ... 10 or 20 contracts before I have to start trading differently because slippage would break everything down.

    My goal is to develop a system to survive when I start trading. I've seen countless journals of people losing their a$$es trading e-minis and not one journal where someone is net positive after several months.

    It isn't looking as glamourous as when I first discovered e-minis.


    #52     Sep 9, 2002
  3. Nobody -- not one person in here -- has come forth and said, "I consistently make profits trading ES futures." I've seen a lot of people keep journals and I respect them for it, but Andy, Huois and the other person who just had a $1,000+ downdraw in one week?

    I've been using a simulator that takes into account slippage and other factors from a brokerage firm and I'm doing quite well -- so something isn't sitting right here.

    I'm starting to really think that trading is 75% mental and 25% system, because it can't be a fluke that I am up around 45% for a month and these people who are using real money are all down.

    Quite frankly, it raises doubts in my own mind whether I will have what it takes when I trade these futures with real money. Then I tell myself I can't think that and I must remain strong or else I'm screwed. Its like the magic mirror -- the Never Ending Story -- the looking glass ... you see your reflection and everything that is messed up about your mind ... and it all comes back to you when you are in the market.

    I enjoy programming and creating these useful tools, but when push comes to shove, I think the dividing line that seperates the rich boys from the break-even guys is all inside the head.

    #53     Sep 9, 2002
  4. Im not buying it.

    If trading is 80% mental, and "easy" as many claim it is, then
    it should be pretty easy to write a fully automated
    trading system.

    Keep it simple...take all yours trades...blah blah...
    These are all things computers are real damn good at,
    and yet, finding a consistently profitable fully automated
    intraday system is difficult.

    Explain that.


    #54     Sep 9, 2002
  5. Prefer more than one moving average,that's part of it.


    ''-Enjoy your read''- Alan Greenburg Bear Stearns:cool:
    #55     Sep 9, 2002
  6. echo


    The perfect moving average would not require any parameters to be manually entered (such as the usual "period").
    #56     Sep 9, 2002
  7. <b>Cool idea, but expand the formulas and see what you really have here:</b> Its always a good idea to expand and combine the mathematical formulas for what you are doing. Often you discover that your effective formula is much simpler than you thought when a bunch of terms cancel out. This can be good if you like to keep things simple. It can be bad, though, if you thought the formula was compensating for something that it really isn't. (I've gotten more than a few chuckles out of some so-called TA's guru's complex "new" formula that just simplifies down to some other well-know TA indicator.)

    <b>Velocity as the difference of two moving averages:</b> Lets look at your calculation of velocity of the price (the difference in the y's). By your description of the program (which is very clearly written, by the way) each successive value of Y is the moving average of 600 raw price datapoints taken from a respective successive window. Thus, for example:

    Y[1] = AVERAGE(X[1] to X[600])
    Y[2] = AVERAGE(X[2] to X[601])

    where X is the raw price data, Y is the moving average, and the square bracket ([ ]) notation says to reference that element of the list of the variable. This moving average can be rewritten as a sum that is then divided by the number of datapoints being averaged:
    Y[1] = SUM(X[1] to X[600])/600
    Y[2] = SUM(X[2] to X[601])/600

    we can expand these sums to a few terms to get a feel for them:

    Y[1] = SUM(X[1] + X[2] + X[3] to X[600])/600
    Y[2] = SUM(X[2] to X[601])/600

    So, what happens when we calculate the velocity of the price using these moving average values? The per-minute estimate of velocity (using moving average values spaced at 200-millisecond intervals) is:

    V[1] = 300*(Y[2] - Y[1])

    The "300" comes from the fact that the raw difference of the Y's is the change in price over a very short period of 200-millisecond. Multiplying by 300 gives us the velocity on a $/minute trend rate. Expanding the formula's for the Y's gives us:

    V[1] = 300* ( SUM (X[2] to X[601])/600 - SUM(X[1] to X[600])/600)
    V[1] = SUM (X[2] to X[601])/2 - SUM(X[1] to X[600])/2)

    <b>All the intermediate terms cancel out:</b> But think about what happens in the subtraction of these two sums. Both sums overlap extensively on the list of X's. Indeed, both sums share X[2] through X[600] for terms. In the subtraction, these shared terms all cancel out. The result is that the velocity formula that is left is only:

    V[1] = (X[601] - X[1])/2

    This formula for the per-minute velocity may not be as smooth as you would like. Any noise in either X[601] or X[1] will appear in your velocity estimate. Worse, any information about the price dynamics contained in terms X[2] through X[600] is lost by this method of velocity calculation. I'm not saying that this approach is wrong, only that it has some behaviors that do not seem quite "perfect."

    <b>Testing this empirically:</b> Admittedly, it was easy to expand and simplify these formulae for estimating price velocity from the moving average of the price. As you progress to more sophisticated moving averages, it may not be easy to replicate this analysis. But you can replicate the analysis empirically by testing how the list of velocity estimates changes in response to a change in a single datapoint someplace. Empirical testing would also let you examine how a blackbox automagical moving average works.

    For example, say we calculate the list of velocity values using this difference-of-moving-averages algorithm. Then we perturb the raw data by adding $1 to, for example, datapoint X[602] and recompute the list of velocities. Next, take the difference of the perturbed and unperturbed velocity data. We will find that V[2] is $0.50/minute higher than before and that V[602] is $0.50/minute lower than before. All other values of the velocity are unchanged, reflecting the fact that X[602] really only contributes to estimating the velocity at two points due to the cancelation of terms.

    By empirically testing the entire system, you learn how one small change in the data someplace can lead to a change in the system someplace else. For more complex nonlinear, adaptive systems, you might try both small and large perturbations, both negative and positive perturbations, and perturbations at various features in the price stream (e.g. at gaps, in the middle of trends, etc.).

    <b>What Are you really after?</b> Maybe creating a smooth estimate of the price is not the best way to go. As it turns out, you really do not care about estimating the price, you only care about estimating the velocity. Think about how you might estimate velocities directly and how you might filter or process those estimates to smooth the noise out of the velocity estimates while avoiding excessive lag.

    You are on to some interesting ideas here, and I'm sure we are all enjoying the mental exercise.

    Thanx for sharing everyone,

    P.S. Don't bother to zip the data files. A new internal 160 GB harddisk costs only about $400 and will provide enough space to 64 years of daily data at 10 MB/file (that's a price of 0.0025/MB or 2.5 cents to store a copy of the file). Zipping and unzipping will only delay your work. (After what good is Moore's law if it can't make your life easier)
    #57     Sep 9, 2002
  8. aphie,

    One issue, with high-speed trading is the total cycle time from the market, through the data service, over the internet to your PC, through you trading system, back over the internet to the broker, and back to the market. Even if the trading system makes decisions instantaneously, there will still be delays in these other parts of the system. The total round-trip cycle time places limitations on whether you can countertrade extrema or jump on microtrends.

    The only way to fully assess the round-trip cycle time is to submit test trades and gauge where they occurred with respect to the incoming datastream (don't trust the timestamps on data or trades until you prove that they are trustworthy). The question is: how many 200-millisecond cycles between when your system sends out an order and that order shows up in the data stream? (It might be a little tricky to pin-down when your order went through, unless the market is trending strongly enough to make the timing of your sale obvious from the price that you got). And, when you get to actual trading, you might want to keep an eye on the cycle time. As you gain experience, you might also discover that certain times of day or certain market conditions are too hard to trade due to excessive cycle times.

    I realize that experiments like this do cost money, both in commissions and in trades that may not be winners. But the answers to the round-trip cycle time question might keep you from working on (or trading) a flawed system. It would be too easy to presume that one can jump on price movements more quickly than one actually can. Also, the book "The Predictors" by Thomas Bass has some excellent anecdotes on the vagaries of working in real-time.

    May speed be with you,
    #58     Sep 9, 2002
  9. Traden4Alpha et al (et tu, Brutus)

    Excellent posts! I will reply them to them in more depth later.

    Here is a picture from the first hour of market movement.

    This is a very basic graph. I took 5 pictures a second of the last agreed upon price and then graphed each 200 millisecond period. If it was greater than the 200 millisecond period before it, it would be higher and green. If it was less, it would be lower and red.

    Here is the distribution of up's and down's ... this is the noise I seek to eliminate (or reduce).

    #59     Sep 9, 2002
  10. Same graph, but this time, we plot price(x) against price (x-500).

    #60     Sep 9, 2002