Wrong value in the first grade graph

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From: Arjan
Sent: Oct 20, 2009, 06:50:00
Subject: SuperMemo error: Wrong value in the first grade graph: 5.098

Question 1

Wrong value in the first grade graph: 5.098

Question 2

It also happens after grading: http://wiki.supermemo.org/index.php?title=File:Wrong_value_in_the_first_grade.jpg


SuperMemo discovered an illegal value in the graph that shows the correlation between the first grade and the A-Factor. Upon discovering an illegal value, SuperMemo corrects it (here to 5.000).

This error has most likely been caused by a bug in the first release of SuperMemo 2008 (Build 14.00). The bug has since been fixed. You may see this message as many times as there are corrupted entries in the graph (i.e. from 1 to 20 times in total).

There is no need to update SuperMemo. This message appears only in the version that has the bug fixed.

You can see the graph in Tools : Statistics : Analysis : Graphs : First Grade vs. A-Factor.

Question 3

kirsten asked:

I've upgraded to Supermemo 15 last week and since then every question I answer has the 'Wrong value in the first grade graph'. I've seen your explanation of what the error means. My collection is around 11000 elements and if I can get the error up to 20 times for each one then I'm still going to be 'entering' past the error message for years.... Is there anyway to correct this error for my entire collection?


This data error is in the graph, not in your elements. First grade graph has 20 entries and this is the maximum number of times you should be able to see that message (unless you stop SuperMemo and disallow saving the corrected data).

Question 3

Are you telling me that in the future I will have to click on it 20x 4000 entries?

Answer 3

If you have 4000 items, you do not need to worry about 4000 errors. The graphs has 20 entries. If they are all corrupted, you will see the message 20 times.

Question 4

I recently bought SM15 and imported my whole >8000 element collection of items from Anki using a self-made Anki addon that exports to SuperMemo XML and preserves rudimentary learning data.

Since then, I have seen the above message in SuperMemo almost constantly. Certainly more than 20 times (yes, I have counted).

If necessary, I can provide my whole SuperMemo collection for debugging.

Answer 4

Please see this separate topic: Problems with imports from Anki

Yes. You could submit your collection. Perhaps there is a weakness in XML import that did not account for some unusual features in your export addon?

For the error to occur more than 20 times, wrong entries in the graph would need to be generated again and again (e.g. if you happened to use the substituted buggy 14.00 version). The reason is that each time SuperMemo reports the error, it corrects the entry. If you quit the collection correctly and save the graph data, the 20 entries will generate maximum of 20 errors.

Answer 4: Debugging conclusions

Thank you for submitting your file sm8opt.dat for inspection.

The file seems to contain correct data, and should not result in raising the said error any more (unless you are using the old version of SuperMemo that was originally causing the bug, or your repeat your import procedure that might be vulnerable to some unusual features of your XML).

Naturally, there might be unknown bugs in SuperMemo that have not yet been reported yet, or there was an error in the inspection process (e.g. sending wrong file, file substitution, human error, etc.).

Your First Grade Graph is correct. All values, like grades in SuperMemo, should fit into the 0..5 range and they do.

If you ever see this error again, please write back with details.

The status of your FirstGradeGraph in sm8opt.dat as debugged in Delphi XE3:

First Grade Graph debugging in sm8opt.dat

More details in response to Answer 4

I imported my >8000 element collection to SuperMemo 15 from Anki using a self-made Anki addon that exports to SuperMemo XML and preserves rudimentary learning data. Since you were not able to find the problem, please find attached an XML file enclosed in a zip archive. Using SuperMemo 15 (build 15.4), I can reproduce the problem as follows:

  1. Create a new collection.
  2. Import the attached XML file.
  3. Start executing repetitions.

Then the "Wrong value in the first grade graph" error quickly appears more than 20 times.

Answer 5: bug in import from Anki

Your XML file is formatted correctly. It imports to SuperMemo 15 without problems. The problem is that there is a hole in the XML specification: it does not include the first grade in the learning process (on the assumption items are created using SuperMemo for Windows and only updated on other platforms). Unfortunately, newer SuperMemos specifically set the first grade to "uninitialized" until the first repetition is executed. Moreover, the algorithm is not immune to feeding it with the uninitialized first grade. This is why it causes update problems at each repetitions.

The bad news is that it cannot be easily fixed without changes to SuperMemo! Both weaknesses should be remedied: (1) first grade should transfer between platforms even if it never changes (e.g. to cover for your case), and (2) the algorithm should ignore uninitialized first grade field and use whatever versions of the first-grade statistic it has (even the default approximation that is generated when first creating a SuperMemo collection).

The changes do not require any major rewrite of code, however, they are unlikely to be fit retroactively due to the low severity of the bug. This may mean that only the next version will be able to effectively import from Anki using your export tool.


For a solution for sm15 users see: Problems with imports from Anki