Alerts

dhall6938

This alert is set up to run on a list I created which holds the indexes such as NDX, SOX,XLK,SPX and a few others. It has alerted me several times this morning but as you can clearly see, none of these were below their SMA(14) today. As you know I have had this problem before but this is a much smaller alert and maybe whatever it is wrong is easier to see? NDX and SOX were the last two to trigger this alert today.

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and [[Close < SMA(14)]

and [High > [[1 Day ago High + 1 Day ago Low] / 2.0]]

and [[MACD Hist(12,26,9) < 1 Day ago MACD Hist(12,26,9)] or [MACD Line(12,26,9) < 1 Day ago MACD Line(12,26,9)]]

and [[MACD Hist(48,103,36) < 1 Day ago MACD Hist(48,103,36)] and [MACD Line(48,103,36) < 1 Day ago MACD Line(48,103,36)]]

and [MACD Hist(72,156,54) < 1 Day ago MACD Hist(72,156,54)]

and [MACD Hist(60,130,0) < 1 Day ago MACD Hist(60,130,0)]

and [MACD Hist(72,156,0) < 1 Day ago MACD Hist(72,156,0)]]

markd

There does seem to be something wrong there.

Even if you run just the first line of the scan, it gets hits on symbols where the close is clearly higher.

dhall6938

And, when I run the scan to verify my alert, it did not select anything as I would expect. I'm at a loss

dhall6938

FYI, I have been running my scans every hour or less for the last several days and if I get an alert, I verify it with by running the scan. The scans and the alerts definitely do not operate the same. As an example, today and yesterday a couple of scans triggered but the alerts did not trigger, or they triggered several hours later. Today, one of my scans has been triggered since the open but the alert has not. Just letting you know if it helps you guys in some way. Thanks again for all of your help

markd

If you have real time charts you can watch the indicators move. Maybe that would help understand what triggers the alerts.

For past bars, indicators only show the ending value for the bar in question, not all the intermediate values that occurred while the bar was still "live". This is unlike price bars, which show the range of prices hit during the bar, not just the final value.

It's possible the alerts are based on those intermediate (disappearing) values, while the scans use the "end of bar" values.

dhall6938

Thank you. Most of my scans and alerts are pretty lengthy with quite a few different criteria making it a bit difficult to see some of them on a chart. I ran my scans all day today from a few minutes after the open until the close. The scans triggered early, within a few minutes of the open but the identical alerts did not start triggering until several hours after the open with one of them not triggering until the close today. I began to notice this difference about a week ago. In any case, it appears to me that the alerts operate a lot differently with the scans being the timeliest. I thought that you guys who try to help everyone might be interested.

markd

OK. The complexity of your scans make it difficult to know what is going on, although as you say, if they are identical, you would think they would trigger around the same time. But again, if they are not run at exactly same time (which is not possible, I suppose), they are most likely looking at different data.

Also, as I've mentioned before, I think, possibly your scans have more conditions or longer parameters than the scan or alert engine can handle. Unfortunately, as far as I know, the language limits are undocumented. The editor only checks for syntax errors, not logic or calculation limits, and apparently if there is a problem during run time it doesn't throw errors as a "real" language would.

If you want to pursue it further, you could test scan vs. alert with very simple scans, e.g. MACD Line x MACD Signal with default parameters, and see if the same problem arises. If it does, then as you say, there is may be a difference between scans and alerts (although the different data problem is still there, so it's not conclusive). If it doesn't, if they both trigger around the same time (accounting for the delay in getting the alert to you, vs. the scan results) then the "too complex" situation is more likely.

dhall6938

Thanks again, you guys are very polite and helpful. I am constantly messing around with these things so I will try something else when I get the mental energy for it. I am sure that I have created scans / alerts that are too complex for the machine. The scans and alerts that I am referring to this time are very short and very simple.