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  • BackTesting Discrepancies???

    Hello,

    I have been running a fair number of backtests on various strategies
    that I have coded using the EFS editor recently.

    I have a few questions regarding the output.

    First I should specify that all my slippage, commissions costs have
    been set to 0 for my backtesting (I'm currently trying to determine which
    if any strategies would work before transactions costs). I am also
    using a default of 1000 shares per trade.

    I have noticed that on several occassions there are discrepancies with
    respect to the prices that the backtester says I would obtain, and what
    the chart says would be obtained. For example, if I wish to be filled
    at the close of a bar, the chart may identify the bar's close at 45.01
    and the backtester at 45. Note I have ensured that both the backtester
    and chart are using the identical symbol.

    I am wondering what other explanations would cause this?

    Another question I have reflects the amount made per trade. On several
    occassion the backtester indicates I would earn 9.99$ if the trade was
    a penny profitable on 1000 shares. Obviously this should read 10$.
    I'm really at a loss to explain this.

    To get a better idea of what I mean you can take the "btEMA.efs"
    formula which I believe comes standard with E Signal in the "Backtesting"
    folder, and run it for 5 days or so. Enter 1000 share default, with no
    commissions costs or slippage.

    At the beginning this seems to work find, but as time progresses you
    will notice that you will see numbers such as 9.99$ in the Profit/***
    Profit column. You will also notice that the price differential between
    where you open and where you close the trades does not always equal the
    profit for the trade (due to the fact that the open and closing prices
    may not reflect what is actually on the chart).

    If you take a look I think you'll see what I'm talking about.

    I'm just wondering if this problem has already been reported, or if
    there is something else I'm missing.

    Oh yeah I'm running E Signal version 7.5.

    I tried emailing the E Signal customer support people and they told me to post this here.

    Thanks in advance for any help you can give me.

    Tom

  • #2
    Hello Tom,

    Thank you for your post. I will be looking into these issues shortly.
    Jason K.
    Project Manager
    eSignal - an Interactive Data company

    EFS KnowledgeBase
    JavaScript for EFS Video Series
    EFS Beginner Tutorial Series
    EFS Glossary
    Custom EFS Development Policy

    New User Orientation

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    • #3
      Hello Tom,

      What I'm seeing looks like a rounding problem with the Strategy Analyzer in many cases. There are others cases where the price in the Strategy Analyzer is slightly less than the chart price, which doesn't seem to be related to rounding, but indeed a bug. I will report the findings to our development team. However, the differences are much less than a penny on a per trade basis. More like $0.0015 in many cases. It just looks like a penny because your display is set to 2 decimal places in your settings and the displayed result is not rounded to reflect the same rounded price from the cursor window of the advanced chart. The affect on the total cumulative profit number is very immaterial so it should not effect your determination of a particular strategy being profitable or unprofitable. If we were to total the numbers using the correctly rounded prices, the total dollar effect on trading 1000 share lots with btEMA.efs on 5min IBM chart over the last 5 days would be well less than $1.00. The current P/L on this back test is showing -$5,707.000977, which would still be in that neighborhood give or take a $1.00.

      For example, in the image below you will see that for trade 2 the Strategy Analyzer is using prices of $93.1999997 and $93.099998, reflecting a loss of $9.996033, which is a $0.00367 difference on this trade from the correct prices of $93.20 and $93.10 (-$10.00). Over a period of 100 trades this would amount to a total difference of about $0.37 or a 0.0065% variance on the cumulative total Profit/Loss number.

      Jason K.
      Project Manager
      eSignal - an Interactive Data company

      EFS KnowledgeBase
      JavaScript for EFS Video Series
      EFS Beginner Tutorial Series
      EFS Glossary
      Custom EFS Development Policy

      New User Orientation

      Comment


      • #4
        check your settings

        check your settings within the back-tester. there is a DISPLAY tab that allows you to set the "number of decimal places". You might have to adjust these.

        I know, for example, with FX charts, I have to increase the decimal to 4 whereas with the emini, only 2.

        This might help.

        Brad
        Brad Matheny
        eSignal Solution Provider since 2000

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        • #5
          Thank You

          Thanks alot for your help guys.

          Tom

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