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Scan malfunction

My favorites list 9 has NDX and SPX only. Interday the weekly Fline for both NDX and SPX are less than it was on the close last Friday. But, it is not picking up either NDX or SPX. Any ideas why ?

[Favorites list is 9] and [[Weekly MACD Line(12,26,9) > 0.0] and [Weekly MACD Line(12,26,9) < Weekly MACD Signal(12,26,9)] and [Weekly MACD Line(12,26,9) < Last week's MACD Line(12,26,9)]]


  • I guess that I should say that I am aware that SPX Fline is above it's signal line, not below it.
  • The complete scan

    [Favorites list is 9] and [[[Weekly MACD Line(12,26,9) > 0.0] and [Weekly MACD Line(12,26,9) > Weekly MACD Signal(12,26,9)] and [Weekly MACD Line(12,26,9) < Last week's MACD Line(12,26,9)]]

    or [[Weekly MACD Line(12,26,9) > 0.0] and [Weekly MACD Line(12,26,9) < Weekly MACD Signal(12,26,9)] and [Weekly MACD Line(12,26,9) < Last week's MACD Line(12,26,9)]]

    or [[Weekly MACD Line(12,26,9) < 0.0] and [Weekly MACD Line(12,26,9) < Weekly MACD Signal(12,26,9)] and [Weekly MACD Line(12,26,9) < Last week's MACD Line(12,26,9)]]

    or [[Weekly MACD Line(12,26,9) < 0.0] and [Weekly MACD Line(12,26,9) > Weekly MACD Signal(12,26,9)] and [Weekly MACD Hist(12,26,9) < Last week's MACD Hist(12,26,9)]]]
  • Weekly MACD Fline numbers. Last Friday close, SPX = 108.166 and NDX = 637.082. At 1:30 central time SPX weekly Fline number = 108.127 and NDX weekly Fline number = 630.896. I wonder if the charts use a seperate data source than the scans use? This has happened to me before but it's almost always gone by the time someone else can see it
  • markdmarkd mod
    edited October 2020
    Yes, the chart engine and the scan engine use different data sources. It may be that one is updating before the other. Also, there are corrections from the data vendors through the day and after the market closes that may not be applied synchronously.
  • Mark, thanks. I am able to watch closely this time and it's pretty far off the mark.
  • The chart turned almost two hours ago and is still fallling but the scans are not. This is not good at all. I didn't realize it was so bad
  • If you understand how the two different data sources work, I wonder if I use a slightly faster MACD would help the scans keep up with the charts? The charts are ahead of the scans by a lot today
  • Intraday? The scan engine isn't designed for intraday scanning. If you run it during the day, you may pick up something or not perhaps, but don't bank on anything that is clearly stating that it's not good for intraday.
  • I did not know or I had forgotten that the scan engine could not be used during the day. I guess that means it's only reliable after the market close every day?
  • Support Center » Frequently Asked Questions » Do you provide real-time stock scanning?
    Sort of. Because of the vast amounts of data involved, all scanning systems work with datasets that are slightly older than “real-time.” When the market is open, our scan engines are continually updating the most recent data point for all of the stocks and indexes that they track on a rotating basis. When an Extra or Pro member runs a scan based on the “Last Intraday Update”, the scan engines will use a “most recent” data point that is somewhere between 5 and 30 seconds old, depending on when the scan is run.
  • dhall6938dhall6938
    edited October 2020
    Bla bla bla
  • Maybe the scan engine requires a lot bigger change than the chart requires. Maybe the time of day has something to do with it.
  • 1 - it's unfair to criticize the site for not doing something it was plainly not intended to do.

    2 - nothing that depends on the internet is 100% reliable. Vendor servers crash, ISP servers crash, site servers crash, phone lines go down, caches overflow, software updates fail, hardware replacements fail, traffic gets re-routed and lost. Tracking down the problem can be complicated.

    3 - it's pretty unorthodox to use weekly data for making decisions intraday; it's also unorthodox to scan a list with only two symbols. Not saying don't do it, but might there be alternatives that work better?
  • 1. Above I posted where they say that the scans should work accurately every 30 seconds throughout the day, unless I misunderstand something. So I don't see that I am being unfair. If I am, I apologize but at this point it seems the opposite to me. If what your saying is true, you can't trust a scan until sometime after the close every day and that may work for some but it doesn't work for me.

    2. I understand about the internet, this time it was not the internet. The charts were updating every 5 seconds and I had an iPad that I also tried to run my scans. This is not the first time that I have noticed this issue but it is the first time that I could tell exactly what it was that was wrong. About two hours passed, give or take a little, before the scan's began to catch up to the charts. I can live with a couple of minutes but two hours is too much time.

    3. What I am trying to do may not make sense to you and being unorthodox is not always a bad thing. As best I can tell from what the site says the scan should run a new list every 5 to 30 seconds throughout the day, barring any issues like the internet and I don't think that is what happened this time.

    I appreciate all of yawls help and advice but I am trading real money and I need this site to work like it's supposed to work or I need to understand what it does and does not do much better
  • The reason that I have created a list with only two symbols is because I am trading only those two indexes using mostly ETFs. So, I use charts for those two indexes to make trade decisions. I have written to SC but I have not heard back yet. Maybe their data for the indexes is delayed compared to the data that they get for individual stocks? All's I know is that for some reason, the 2 charts that I watch updated much faster (2hrs) than the scans yesterday.
  • I guess my question would be, if you have only two symbols to review, why scan at all?

    But again, if it works for you, stay with it.

  • Good question. At one time I was watching more than just two symbols but I found that I would make more money trading just those two so I abandoned the rest. It's a lot easier than trying to manage more. When I am not at my computer it's much easier to run a scan rather than trying to see a weekly Fline on a chart from my phone. Also, on a weekly chart the numerical changes in some of what I want to see are so slight that it's difficult to see the indicator change with my eye. I have to actually write down the values and compare them. But, good question. The site has not written back so I am about to assume that they didn't like my questions from yesterday and are going to ignore me. If you happen to be a part of SC, you guys might want to change what the site says it will do, I posted it above. Thanks again
  • Mark, don't know if your interested or just wished that I'd go away but I have been watching my weekly macd fline closely again today. The chart matched the scan within one minute today as opposed to about 2 hours yesterday. Strange to me.
  • Well, as I noted above, any number of technical problems could have been the cause.
  • Yes sir, you did.
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