Am I the only who thinks that looking at each teams performance over the first 8 games and the next spell of 8 games is actually pretty cool? Just me then.

8 game splits is a tiny sample to work with, so any information is merely helpful rather than definitive. Hell, even 19 game splits would be an insufficient sample to work with.

What will follow is a collection of stat tables and the repeatability of each stat from the first 8 games of the season to the second 8 games of the season. Each group of 8 games is separate and none of the information overlaps. I must also state that this article is merely foreplay to a main event which will look at which stats are the best predictors of future goal difference or points totals.

It's all well and good knowing which stats are repeatable, but what we really really want to know are which stats are predictive of future outcomes in terms of the aforementioned goal difference and points. But that's for next time.

OK, we'll start.

Points

Points	Games 1-8	Games 9-16
Arsenal	19	16
Aston Villa	10	9
Cardiff	8	9
Chelsea	17	16
Palace	3	10
Everton	13	16
Fulham	10	3
Hull	11	8
Liverpool	17	16
Man City	16	16
Man United	11	14
Newcastle	11	16
Norwich	8	11
Southampton	16	9
Stoke	8	10
Sunderland	2	6
Swansea	10	10
Tottenham	16	11
West Brom	10	5
West Ham	9	6

Southampton, West Brom and Fulham were the teams who dropped off to the largest degree in the first  8 games v the next 8 games. Palace improve.

Pretty meh relationship between the two sets of results. I'd include goal difference at this juncture but the results are too similar.

Shots +/-

Shots +/-	Weeks 1-8	Weeks 9-16
Arsenal	18	7
Aston Villa	-6	-14
Cardiff	-59	-54
Chelsea	65	39
Palace	-28	0
Everton	26	28
Fulham	-86	-63
Hull	-44	1
Liverpool	-2	69
Man City	56	67
Man United	15	-3
Newcastle	26	10
Norwich	-40	-34
Southampton	19	29
Stoke	-9	-38
Sunderland	-10	-65
Swansea	16	-1
Tottenham	67	38
West Brom	-10	2
West Ham	-14	-18

Palace improved, Liverpool blew the doors off. Tottenham, Chelsea and Man United regressed. Quality of opposition may well be a big factor here.

R2 of 0.55 isn't too bad at all.

Shots On Target +/-

SoT +/-	Weeks 1-8	Weeks 9-16
Arsenal	16	10
Aston Villa	-5	-5
Cardiff	-32	-14
Chelsea	24	16
Palace	-20	4
Everton	19	13
Fulham	-20	-23
Hull	-14	-9
Liverpool	7	27
Man City	28	25
Man United	10	-1
Newcastle	3	5
Norwich	-17	-20
Southampton	12	9
Stoke	-9	-15
Sunderland	-23	-7
Swansea	16	3
Tottenham	22	3
West Brom	-6	-12
West Ham	-11	-9

Huh, Cardiff, Palace and Sunderland all improved in the second chunk of 8 games.

Tottenham, Swansea and Man United regressed.

Slight improvement on the predictability when using shots on target instead of shots. Still early in the season, though.

Scoring%

Scoring=goals for/shots on target for

SC%	Weeks 1-8	Weeks 9-16
Arsenal	33.96	42.86
Aston Villa	33.33	25.93
Cardiff	42.11	18.18
Chelsea	29.17	46.15
Palace	27.27	20.00
Everton	26.67	35.90
Fulham	34.62	24.00
Hull	31.82	33.33
Liverpool	27.66	52.00
Man City	38.46	60.00
Man United	25.58	44.83
Newcastle	27.50	29.41
Norwich	24.00	31.03
Southampton	21.05	36.36
Stoke	13.79	45.83
Sunderland	26.32	38.89
Swansea	25.53	33.33
Tottenham	16.67	15.56
West Brom	28.00	34.48
West Ham	38.10	17.24

Scoring% is pretty much all over the place. Here's how the first bucket of scoring% predicts the second bucket of scoring%:

A correlation of 0.01 between two sets of variables is really poor. Essentially there is no relationship.

Save%

Save= 100-(goals against/shots on target against)

SV%	Weeks 1-8	Weeks 9-16
Arsenal	75.68	66.67
Aston Villa	68.75	66.67
Cardiff	74.51	75.68
Chelsea	79.17	48.00
Palace	59.52	63.16
Everton	61.54	83.33
Fulham	78.26	54.55
Hull	75.00	65.52
Liverpool	82.50	66.67
Man City	62.50	57.14
Man United	69.70	68.97
Newcastle	62.16	74.19
Norwich	69.05	68.00
Southampton	88.46	45.45
Stoke	81.58	67.57
Sunderland	52.38	65.52
Swansea	64.52	61.54
Tottenham	80.77	50.00
West Brom	80.65	60.00
West Ham	75.00	67.65

Again, this is pretty much all over the place.

A negative slope to this chart. A negative correlation is probably best explained like this:

The more time I spend at the mall, the less money I have. The more time I spend at the office, the more I question the purpose of existence.

The higher a team save% was in the first 8 games the lower it is likely to be in the next 8 games. But that effect isn't huge, the correlation is just r2=0.22.

Save% and Scoring% numbers in the first 8 games were shitty predictors of Save% and Scoring% in the next 8 games. What happens if we put both of these stats together and call it PDO?

PDO

PDO	Games 1-8	Games 9-15
Arsenal	109.6	109.5
Aston Villa	102.1	92.6
Cardiff	116.6	93.9
Chelsea	108.3	94.2
Palace	86.8	83.2
Everton	88.2	119.2
Fulham	112.9	78.5
Hull	106.8	98.9
Liverpool	110.2	118.7
Man City	101.0	117.1
Man United	95.3	113.8
Newcastle	89.7	103.6
Norwich	93.0	99.0
Southampton	109.5	81.8
Stoke	95.4	113.4
Sunderland	78.7	104.4
Swansea	90.0	94.9
Tottenham	97.4	65.6
West Brom	108.6	94.5
West Ham	113.1	84.9

In most cases PDO shows little or no relationship from the first group of 8 games to the next group of 8 games.. The chart points this out:

A very slight negative correlation. But it's a wash really. Many people will point to our advanced understanding of shots location and their importance in separating teams from their basic numbers. Maybe they have a point, but the early season splits, and the r2 valuations in scoring%, save% point to those stats having very little repeatability league wide.

I think Mike Goodman put it best:

@colinttrainor @gnepon @benjaminpugsley so either shot locations don't persistently impact PDO or they themselves aren't repeatable.

— Mike L. Goodman (@TheM_L_G) December 10, 2013

*****

Putting all this information together we end up with a table like this:

	R2
Sot For	0.68
SoT +/-	0.59
Goals For	0.56
Shots +/-	0.55
Shots Against	0.53
SoT For %	0.42
Shots for	0.37
Points	0.35
Goal Difference	0.31
SoT Against	0.21
Goals Against	0.13
Scoring%	0.01
SoT Rating%	-0.001
PDO	-0.05
SoT Prevention%	-0.14
Save%	-0.22

I could have included around 15 or 20 other stat categories, but I think we've all seen enough for now.