Wins/losses chart

[Lys]

I have some doubt on wins/losses chart reliability.
Please see the image: 3 wins vs. weaker opponent not showing in the histogram. The same for the 2 losses vs. weaker opponents.
Is it a bug?

I noticed it since august 2017 after the changing of rating system.

OGS has a new Glicko-2 based rating system! [2017]

I looked at your ranking diagram and noticed that some losses are not visible in the bars of the histogram in the lower side: no purple at all since july 2016 until may 2017! Maybe there’s a bug in the histogram itself… or maybe the bug affects also the ranking calculation… (even though losing some losses should reasonably cause a higher rank instead of a lower one).

At that time many had doubts on the new ranks but I can’t imagine if the two tings could be related.

[Lys]

Another example. Here I selected one month. 1+7 losses not showing in the histogram.

[Eugene]

You are correct - I’m glad you reported this.

I had previously submitted a bug report about this, but didn’t have a lot of good evidence.

(In fact, I’d only seen it on the test server, so it wasn’t completely certain that it was even a real problem).

So your real-life example is good to prove that it is.

In case you are interested, the bug report is here: https://github.com/online-go/online-go.com/issues/466

[Eugene]

I think I’ve track this down. Or at least, I have some explanation of some things I didn’t know before.

1. The win/loss bars are only valid for whole months. They span a whole month. You can’t look at sub-month portions of them.

At the beginning and end of any graph, there are bars that are “chopped off” - if you imagine the graph going in to the past, before you started, your bars would extend back there.

This matters, because the weak-losses bar is on the left of the month. So it will likely be missing from the first month on your graph, on the left. The same sort of thing on the right.

2. There is a slightly-wrong number in the code that scales the bars, so a very small bar, like if you have 1 weak loss and 5 weak wins then you have a small weak loss bar - that will disappear.

GaJ

[Lys]

Yes, in general seems that the purple bar is too thin.

1 loss vs 10 wins: it disappears.

4 loss vs 12 win: it’s too thin. I expect it should be 1/4 of the total height.

Also, when there are too few data to display, the vertical axis flips!

[Eugene]

Yes, I’ve submitted a fix for that.

I’ve also suggested (and submitted) that the truncated months are simply removed, and it only shows complete months, for reduced confusion about what we’re seeing.

[Eugene]

@lysnew

Also, when there are too few data to display, the vertical axis flips!

I missed that part. What do you mean by this: I can’t spot the effect you’re talking about?

[Lys]

Look at the numbers on the right vertical axis in the last image: lower rank (18k) is on top and higher rank (7k) is at the bottom. Same for numbers on the left vertical axis: higher number meaning higher rank is at the bottom.

[Eugene]

Oh, up there yeah that’s very wierd! I should be able to find that one!