XG

[Whitey Grandad]

34 minutes ago, Patrick Bateman said:

I work closely with data, I understand data, but xG is a complete load of crap.  According to that stat, Man City (with rounding) SHOULD have won 2-1.  They didn't, that wasn't the score.  So a retrospective at what was expected is a load of rubbish. 

You are supposed to take learnings from data, what can you learn from that? "You SHOULD have scored" and "you SHOULD have hit the target" - brilliant. I think the qualitative data from staff and fans grumbling in the stands is enough to form that view.

Data for data's sake. There are examples of it everywhere.

Look at a shampoo advert; "loved by 89% of people" ... "note: 89% of 63 people" ... WTF is that? That's not a rep sample. Who are these people, what's their demographics, are they a broad enough spectrum and what would give more significance? 1000, 2000, probably 20000.  Anyway, I'm ranting now, your fault. Bloody xG my arse. 

Well said. Statistics have their place but they have to be used in context. Using statistics you can prove that wind is caused by trees waving their btanches.

[Saint86]

5 hours ago, Ex Lion Tamer said:

I think you're underappreciating how much he still had to do and what a great finish it was

JWP penalty vs Brighton was given a 0.76xG (as stated by gecko above). Alvarez 6yard dead centre tap in was 0.5xG. circa 0.15 for Mara's rather difficult half volley seems reasonable to me.

 

3 hours ago, Ex Lion Tamer said:

I for one hadn't clocked that City actually had the best chances in that game so the stat was useful. Doesn't take away from the fact that we finished better and deserved to win

It does add a useful statistical analysis to football - particular for overall team/tactical effectiveness, and for analysing player performance Overall it highlights what good finishes our two goals were. Mara in particular was super movement and a cracking finish. Djenpo as well is a very good finish/awareness.

What the xG stats do show is that we did a good job in keeping City's expected goals well below normal, but that equally we had the quality on the day to finish whilst they were off form and didn't take the chances they made. Versus Brighton the opposite was true re finishing quality - But even though we were outplayed by Brighton, the score did flatter them.

Edited 13 January, 2023 by Saint86

[notnowcato]

5 minutes ago, Whitey Grandad said:

It's bollox because the data taht is extracted bears no relationship to what happened on the pitch.

Case in point

[aintforever]

8 minutes ago, Whitey Grandad said:

A clue as to what? 

That we have been shit obviously.

[notnowcato]

3 hours ago, Whitey Grandad said:

Why is it that xG never comes close to the actually result of a game, even with the benefit of hindsight?

Anyone who was at that game on Wednesday will have come away thinking that Saints could well have scored three or four whilst City might have got one. If they were very lucky.

No I didn’t, City had 2 great chances to score, another day they score them. 

[aintforever]

6 minutes ago, Whitey Grandad said:

Well said. Statistics have their place but they have to be used in context.  

I thought they were all bollocks, now you are saying exactly what I said - they need to be understood and used in context.

xG is only a crude measure of chance quality not the outcome of the game. It doesn’t imply that team that has the highest xG in a game should win, just that they might have had more clear cut goal-scoring chances.

The name “expected goals is just derived from the mathematical concept of “expected value” - a measurement of probability. Like any stat, on it’s own it is pretty meaningless but used in context it has value.

[Whitey Grandad]

1 minute ago, aintforever said:

That we have been shit obviously.

Yes of course, but did xG tell you that or was it the results?

[Whitey Grandad]

1 minute ago, notnowcato said:

No I didn’t, City had 2 great chances to score, another day they score them. 

That's not what I saw.

[Ex Lion Tamer]

Just now, Whitey Grandad said:

That's not what I saw.

Which is exactly why we have stats to help us explore the vastly different opinions people have from watching a game

[notnowcato]

49 minutes ago, Weston Super Saint said:

You've only listed one type...

I'm assuming you've deliberately left out the second in a hilarious way of saying all others are stupid, yet you neglect to factor in a third group that can extrapolate information from data and still think it's shit.

Lies, damned lies and statistics ..... 

Au contraire mon ami. It is you calling others stupid and it’s you interpreting the extrapolated data as shit. It’s not the data, data does not judge nor guide. 

[notnowcato]

3 minutes ago, Whitey Grandad said:

That's not what I saw.

I can’t help that. I don’t have 20-20 vision but Haaland and Alvarez had very good opportunities to score. 

[notnowcato]

6 minutes ago, aintforever said:

I thought they were all bollocks, now you are saying exactly what I said - they need to be understood and used in context.

xG is only a crude measure of chance quality not the outcome of the game. It doesn’t imply that team that has the highest xG in a game should win, just that they might have had more clear cut goal-scoring chances.

The name “expected goals is just derived from the mathematical concept of “expected value” - a measurement of probability. Like any stat, on it’s own it is pretty meaningless but used in context it has value.

Indeed, with the probability derived thousands of games; not just the game we’re considering in isolation. 

[aintforever]

5 minutes ago, Whitey Grandad said:

Yes of course, but did xG tell you that or was it the results?

The stats - the points per game ratio. xG is not meant for anything other than give an idea of the quality of chances created.

[Saint86]

11 minutes ago, Whitey Grandad said:

But xG is never anywhere close to the actual goals scored, which it should be if it ever meant anything.

I mean, there are games when its pretty damn close. But funnily enough, the exact same thing can be said for total shots, but it won't mean much if all those shots are from 35yards and easily saved... 🧐

 

46 minutes ago, Patrick Bateman said:

I work closely with data, I understand data, but xG is a complete load of crap.  According to that stat, Man City (with rounding) SHOULD have won 2-1.  They didn't, that wasn't the score.  So a retrospective at what was expected is a load of rubbish. 

You are supposed to take learnings from data, what can you learn from that? "You SHOULD have scored" and "you SHOULD have hit the target" - brilliant. I think the qualitative data from staff and fans grumbling in the stands is enough to form that view.

Data for data's sake. There are examples of it everywhere.

Look at a shampoo advert; "loved by 89% of people" ... "note: 89% of 63 people" ... WTF is that? That's not a rep sample. Who are these people, what's their demographics, are they a broad enough spectrum and what would give more significance? 1000, 2000, probably 20000.  Anyway, I'm ranting now, your fault. Bloody xG my arse. 

You work with stats, yet you think that city's xG of 1.0 over 90min means they should have scored 2 goals? and that our xG of 0.5 means we should have scored 1? 🧐 okay... 😅

You guys that don't like the data analysis or understand it do realise that that is okay right? No one is forcing you to?

Whereas I personally found it interesting that City's xG of 1.0 for the match was lower than Haaland's individual average xG per 90minutes for the season, let alone the rest of the city side. Clearly our defence and tactical setup was very effective. 

[Whitey Grandad]

14 minutes ago, notnowcato said:

I can’t help that. I don’t have 20-20 vision but Haaland and Alvarez had very good opportunities to score. 

After my lens replacements I now have better than 20-20 vision but that's not necessary for this game. When was Haaland's 'very good' opportunity?

[Whitey Grandad]

12 minutes ago, aintforever said:

The stats - the points per game ratio. xG is not meant for anything other than give an idea of the quality of chances created.

It used to be reckoned on one goal for every six chances. Overall.

[Convict Colony]

Data builds a picture but your eyes tell you if it's any good.

[notnowcato]

Just now, Whitey Grandad said:

After my lens replacements I now have better than 20-20 vision but that's not necessary for this game. When was Haaland's 'very good' opportunity?

You can see it on the XG graph posted on Twitter. Can’t remember the minute but it was a lovely dink of a cross from left central which Halaand somehow managed to make a complete Horlicks of it, any meaningful touch would have diverted it away from Gavin. 

[Ex Lion Tamer]

IS xG now a culture war issue alongside female pundits and taking the knee?

[Whitey Grandad]

19 minutes ago, Ex Lion Tamer said:

Which is exactly why we have stats to help us explore the vastly different opinions people have from watching a game

That's only of any use if the stats are accurate, representative and objective. 

Each goal chance is treated statistically as a separate independent 'event' yet this is far from the case. Once a team has gone 2-0 up in a game, no matter how 'unexpected' these goals may have been, they will naturally concentrate on keeping the game tight from then on. This means that they will typically have fewer goal chances as the game progresses. Therefore to sum up all the perceived chances in a game and give each of them an individual probability of success which is then added to the others to give a final xG total for their team is misleading. 

[tpbury]

11 minutes ago, Saint86 said:

I mean, there are games when its pretty damn close. But funnily enough, the exact same thing can be said for total shots, but it won't mean much if all those shots are from 35yards and easily saved... 🧐

 

You work with stats, yet you think that city's xG of 1.0 over 90min means they should have scored 2 goals? and that our xG of 0.5 means we should have scored 1? 🧐 okay... 😅

You guys that don't like the data analysis or understand it do realise that that is okay right? No one is forcing you to?

Whereas I personally found it interesting that City's xG of 1.0 for the match was lower than Haaland's individual average xG per 90minutes for the season, let alone the rest of the city side. Clearly our defence and tactical setup was very effective. 

I think this started as a technical discussion about how xg was implemented. I really don't think you or anyone else is demanding it should be used as the only measure of how a game went. 

So the emotionality should really be kept at bay - if the idea of these stats pisses you off, you don't have to be bothered about it. Some coaches/scouts might use it, but they're not going to blab about how they use it!

[Whitey Grandad]

3 minutes ago, notnowcato said:

You can see it on the XG graph posted on Twitter. Can’t remember the minute but it was a lovely dink of a cross from left central which Halaand somehow managed to make a complete Horlicks of it, any meaningful touch would have diverted it away from Gavin. 

At the time I never considered that to have been a reasonable chance of a goal. Similarly with Alvarez, I could see that the cross was too far away from him for him to get anything solid on the ball. Perhaps this is a difference between watching the game live or watching it on TV, which presumably is what the statisticians do.

[notnowcato]

1 minute ago, Whitey Grandad said:

At the time I never considered that to have been a reasonable chance of a goal. Similarly with Alvarez, I could see that the cross was too far away from him for him to get anything solid on the ball. Perhaps this is a difference between watching the game live or watching it on TV, which presumably is what the statisticians do.

No doubt some football data is still recorded by humans but the advances in video analysis are slowly eradicating the human element in data collation. 
 

You’re potentially showing a bias in your interpretation of an event. Maybe you’re seeing the event as either a 0 or 1 outcome.

[Ex Lion Tamer]

23 minutes ago, Whitey Grandad said:

That's only of any use if the stats are accurate, representative and objective. 

Each goal chance is treated statistically as a separate independent 'event' yet this is far from the case. Once a team has gone 2-0 up in a game, no matter how 'unexpected' these goals may have been, they will naturally concentrate on keeping the game tight from then on. This means that they will typically have fewer goal chances as the game progresses. Therefore to sum up all the perceived chances in a game and give each of them an individual probability of success which is then added to the others to give a final xG total for their team is misleading. 

That's a very interesting and valid point but I think it only reinforces the need to be thoughtful in the way we interpret xG, rather than an argument that xG is a load of bollocks

[Give it to Ron]

16 minutes ago, Ex Lion Tamer said:

That's a very interesting and valid point but I think it only reinforces the need to be thoughtful in the way we interpret xG, rather than an argument that xG is a load of bollocks

Or because we are old men we don’t agree with it?

[aintforever]

1 hour ago, Whitey Grandad said:

That's only of any use if the stats are accurate, representative and objective. 

Each goal chance is treated statistically as a separate independent 'event' yet this is far from the case. Once a team has gone 2-0 up in a game, no matter how 'unexpected' these goals may have been, they will naturally concentrate on keeping the game tight from then on. This means that they will typically have fewer goal chances as the game progresses. Therefore to sum up all the perceived chances in a game and give each of them an individual probability of success which is then added to the others to give a final xG total for their team is misleading. 

That's not the stat being misleading, it's you not understanding what it is for. It is not supposed to be a measure of who is the best team or who should win, just a gauge of the quality of chances created.

A team can be by far the better team, win the game comfortably but still have a low Xg. For example of they go 2-0 up early on with a couple of worldies then sit back and just defend well for 80 minutes they would probably have a very low Xg.

Edited 13 January, 2023 by aintforever

[Turkish]

1 hour ago, Ex Lion Tamer said:

IS xG now a culture war issue alongside female pundits and taking the knee?

all 3 now need putting in the bin

Apart from Alex Scott she can stay.

[Ex Lion Tamer]

21 minutes ago, Give it to Ron said:

Or because we are old men we don’t agree with it?

It comes across that way when people get emotional/aggressive about it

Edited 13 January, 2023 by Ex Lion Tamer

[Turkish]

Just now, Ex Lion Tamer said:

It comes across that way when people get emotional/aggressive about it

who is getting emotional/aggressive about it?

[Ex Lion Tamer]

9 minutes ago, Turkish said:

who is getting emotional/aggressive about it?

  

8 hours ago, Weston Super Saint said:

I think that highlights everything you need to know about the bullshit that is xG / xX . 

Made up bollocks to keep spotty teenagers and adult nerds happy.

 

On 11/01/2023 at 23:56, S-Clarke said:

I will forever believe that Xg is just nonsense

 

On 12/01/2023 at 00:01, John Boy Saint said:

Maybe it just means Xtremely Gullible 

 

15 hours ago, Turkish said:

 

7 hours ago, Nolan said:

I agree with Turkish. B*llocks and simply nudge theory for gamblers.

 

6 hours ago, egg said:

It's bollox.

 

6 hours ago, Lee On Solent Saint said:

Jesus Christ

 

5 hours ago, Whitey Grandad said:

Nope. It’s rubbish

 

1 hour ago, Whitey Grandad said:

It's bollox 

 

[John Boy Saint]

3 minutes ago, Ex Lion Tamer said:

  

 

 

 

 

 

 

 

 

 

Wow if all of that is considered emotional or aggressive - the world truly has gone to shit!

 

[Weston Super Saint]

1 hour ago, notnowcato said:

No I didn’t, City had 2 great chances to score, another day they score them. 

City had ZERO shots on target.  On another day, they still would not have scored if they don't hit the target.

[S-Clarke]

7 minutes ago, Ex Lion Tamer said:

  

 

 

 

 

 

 

 

 

 

So the answer is no, no one is getting emotional and aggressive about it.

[Weston Super Saint]

Once upon a time, spotty teenagers had porn mags to get their rocks off over.  Now it's whether or not a chance was high enough on the xG scale.

Different times I guess.

[Ex Lion Tamer]

11 minutes ago, S-Clarke said:

So the answer is no, no one is getting emotional and aggressive about it.

They seem like quite strong opinions to have about a statistical calculation to me. But ok 😃

[Whitey Grandad]

1 hour ago, aintforever said:

That's not the stat being misleading, it's you not understanding what it is for. It is not supposed to be a measure of who is the best team or who should win, just a gauge of the quality of chances created.

A team can be by far the better team, win the game comfortably but still have a low Xg. For example of they go 2-0 up early on with a couple of worldies then sit back and just defend well for 80 minutes they would probably have a very low Xg.

Then what is the point of it? I am genuinely interested.

[Whitey Grandad]

20 minutes ago, Weston Super Saint said:

Once upon a time, spotty teenagers had porn mags to get their rocks off over.  Now it's whether or not a chance was high enough on the xG scale.

Different times I guess.

I know which I prefer.

[Turkish]

46 minutes ago, Ex Lion Tamer said:

  

 

 

 

 

 

 

 

 

 

So although others have also said it as i asked the question will also add, the answer is no one then.

[Fabrice Fernandes no.1 fan]

9 minutes ago, Whitey Grandad said:

Then what is the point of it? I am genuinely interested.

It is a good metric for the quality of chance a team is producing against the end result, over a spread of games. For example, a team that has 3.5xg per game across half a a season but is only scoring 1 goal a game is making chances but not finishing them, but a team who have 0.5xg per game but score a goal a game are not making enough chances but are finishing those they do have well.

It is also useful for measuring a striker's ability. If a striker is scoring above their expected goals, you can infer they are likely a better finisher, or more in form, than someone who is scoring below their expected goals.

It is less useful when applied to specific circumstances, and better over a wider spread of data. 

However, it does represent Wednesday quite well, our two chances weren't the easiest, and so you would not expect us to score that often. Djenepo misses that chance more often than he scores it, so it has low XG. 

[notnowcato]

39 minutes ago, Weston Super Saint said:

City had ZERO shots on target.  On another day, they still would not have scored if they don't hit the target.

You appear to be confusing outcome with probability of outcome.

[Convict Colony]

[notnowcato]

11 minutes ago, Turkish said:

So although others have also said it as i asked the question will also add, the answer is no one then.

Or you're proving why objective data is better than subjective.  Clever.

[egg]

59 minutes ago, Ex Lion Tamer said:

  

 

 

 

 

 

 

 

 

 

Me pointing out that it's bollox is not me being aggressive or emotional. It's my opinion. 

[Turkish]

1 minute ago, egg said:

Me pointing out that it's bollox is not me being aggressive or emotional. It's my opinion. 

These days if you dont have an opinion that is the same as someone else then you're being aggressive and emotional. Or as some of the thicker posters on here might say "pissing your pants"

[Saint86]

1 hour ago, Ex Lion Tamer said:

  

 

 

 

 

 

 

 

 

 

Post of 2023 contender 🤣

[Saint86]

1 hour ago, Whitey Grandad said:

Then what is the point of it? I am genuinely interested.

Several examples have been set out above. Put simply, xG adds a nuanced way to interpret team and player performances, such as looking at the effectiveness of a team's attacking play, a player's finishing, or the effectiveness of a tactic / defence at nullifying the attack of an opposition team. For example, we had minimal possession in the city game, but defended well and limited city's entire attack to less expected goals than haaland's average xG for a game this season 👍. That's a significant reduction.

We were then able to use the circa 25-30% possession we had efficiently to generate some decent chances and  had mara (who statistically is a decent finisher) to take advantage of it. It was a good performance where tactically we were very solid and maintained a threat, but the stats show that city still had the chances and should really have scored - e.g. on another night city start haaland, and the Alvarez chance is a goal (as an example), or haaland hasn't just come on to somehow completely miss his header in front of goal. 

If you'd rather count all shots / shooting chances as equal then ofc fee free 😢, but there is definetly value in the newer statistical analysis methods. 

Similarly we should be targeting attacker's that have a high xG conversion rate. 

Edited 13 January, 2023 by Saint86

[Weston Super Saint]

54 minutes ago, notnowcato said:

You appear to be confusing outcome with probability of outcome.

You're a weirdo!

If a team has zero shots on target, the probability of scoring is zero.

If a team has zero shots on target, the outcome will be zero goals.

There is no confusion when the answer is zero both times.

[Weston Super Saint]

58 minutes ago, Fabrice Fernandes no.1 fan said:

 

It is also useful for measuring a striker's ability. If a striker is scoring above their expected goals, you can infer they are likely a better finisher, or more in form, than someone who is scoring below their expected goals.

Why?

Why aren't you inferring that the goalkeepers they have played against are absolute dog shit (aka Scottish)?

[Saint86]

17 minutes ago, Weston Super Saint said:

You're a weirdo!

If a team has zero shots on target, the probability of scoring is zero.

If a team has zero shots on target, the outcome will be zero goals.

There is no confusion when the answer is zero both times.

🤦‍♂️ Because yes, if we replayed the chances, then every single time haaland jumps for that header he will miss the goal. And every time Alvarez hits that cross he'll slice it wide 

Edited 13 January, 2023 by Saint86

[polegategavin]

I just can’t see how xG determined we had a probability of scoring at less than 1 and Man City had a probability oF more than 1 when the chances in the game were at best similar, and the fact that a lobbed shot and a stroked home shot for our 2 goals did not require anything unusual or exceptional to provide our 2 goals. When the xG for us isn’t somewhere between 1 and 2 in this particular game, I am sceptical about the logic of the analysis.