Wednesday, August 26, 2020

Which World XI would Jimmy fit into, while taking into account aggregate

When I posted this thread yesterday, I suspected the main concern would be to do with sample sizes, leading to some players with short careers appearing high on the lists. The main concern generated through such is sample size, which reducing overall certainty in the results.

Of the results, the most controversial were around the bowlers as they were picked, below is the top 50 for your consideration:

Rank Player Matches Wickets Average WPM Era Adjust Rating
1 SF Barnes (ENG) 27 189 16.43 7.000 26.54 18.58 0.6139
2 Sir RJ Hadlee (NZ) 86 431 22.30 5.012 32.17 20.79 0.4910
3 MD Marshall (WI) 81 376 20.95 4.642 32.25 19.49 0.4881
4 PJ Cummins (AUS) 30 143 21.83 4.767 32.11 20.39 0.4835
5 GD McGrath (AUS) 124 563 21.64 4.540 33.10 19.62 0.4811
6 DW Steyn (SA) 93 439 22.95 4.720 33.56 20.52 0.4796
7 DK Lillee (AUS) 70 355 23.92 5.071 31.86 22.53 0.4745
8 J Garner (WI) 58 259 20.98 4.466 31.54 19.95 0.4731
9 Mohammad Asif (PAK) 23 106 24.37 4.609 35.17 20.78 0.4709
10 AA Donald (SA) 72 330 22.25 4.583 31.92 20.92 0.4681
11 FS Trueman (ENG) 67 307 21.58 4.582 30.91 20.95 0.4677
12 CEL Ambrose (WI) 98 405 20.99 4.133 31.85 19.77 0.4572
13 K Rabada (SA) 43 197 22.96 4.581 31.21 22.07 0.4556
14 AK Davidson (AUS) 44 186 20.53 4.227 30.17 20.42 0.4550
15 RJ Harris (AUS) 27 113 23.52 4.185 33.95 20.79 0.4487
16 CEH Croft (WI) 27 125 23.30 4.630 29.93 23.36 0.4452
17 Waqar Younis (PAK) 87 373 23.56 4.287 32.54 21.72 0.4443
18 AV Bedser (ENG) 51 236 24.90 4.627 31.76 23.52 0.4436
19 Imran Khan (PAK) 88 362 22.81 4.114 32.23 21.23 0.4401
20 SR Clark (AUS) 24 94 23.86 3.917 35.33 20.26 0.4397
21 NAT Adcock (SA) 26 104 21.11 4.000 30.05 21.07 0.4357
22 BA Reid (AUS) 27 113 24.64 4.185 32.93 22.45 0.4318
23 SM Pollock (SA) 108 421 23.12 3.898 33.09 20.96 0.4313
24 MA Holding (WI) 60 249 23.69 4.150 31.68 22.43 0.4301
25 PM Pollock (SA) 28 116 24.19 4.143 32.33 22.44 0.4296
26 Wasim Akram (PAK) 104 414 23.62 3.981 32.20 22.00 0.4253
27 Mohammad Abbas (PAK) 21 80 21.70 3.810 30.04 21.67 0.4192
28 AME Roberts (WI) 47 202 25.61 4.298 31.16 24.66 0.4175
29 MG Johnson (AUS) 73 313 28.41 4.288 34.45 24.74 0.4163
30 CA Walsh (WI) 132 519 24.45 3.932 32.17 22.80 0.4153
31 N Wagner (NZ) 48 206 26.60 4.292 32.06 24.90 0.4152
32 MA Starc (AUS) 57 244 26.98 4.281 32.09 25.22 0.4120
33 JA Snow (ENG) 49 202 26.67 4.122 32.64 24.51 0.4101
34 VD Philander (SA) 64 224 22.32 3.500 32.17 20.82 0.4100
35 Shoaib Akhtar (PAK) 46 178 25.70 3.870 33.24 23.19 0.4085
36 TM Alderman (AUS) 41 170 27.15 4.146 32.57 25.01 0.4072
37 IR Bishop (WI) 43 161 24.28 3.744 32.09 22.70 0.4062
38 RR Lindwall (AUS) 61 228 23.03 3.738 30.36 22.75 0.4053
39 Fazal Mahmood (PAK) 34 139 24.71 4.088 29.71 24.95 0.4048
40 JM Anderson (ENG) 156 600 26.80 3.846 33.62 23.91 0.4011
41 WW Hall (WI) 48 192 26.39 4.000 31.62 25.04 0.3997
42 MHN Walker (AUS) 34 138 27.48 4.059 32.42 25.43 0.3995
43 JL Pattinson (AUS) 21 81 26.33 3.857 32.03 24.67 0.3955
44 JR Hazlewood (AUS) 51 195 26.20 3.824 31.83 24.69 0.3935
45 TA Boult (NZ) 67 267 27.66 3.985 32.09 25.86 0.3926
46 MG Hughes (AUS) 53 212 28.38 4.000 32.80 25.96 0.3925
47 CJ McDermott (AUS) 71 291 28.63 4.099 32.22 26.66 0.3921
48 JN Gillespie (AUS) 71 259 26.14 3.648 33.01 23.75 0.3919
49 DW Fleming (AUS) 20 75 25.89 3.750 31.48 24.68 0.3898
50 RGD Willis (ENG) 90 325 25.20 3.611 31.79 23.78 0.3897

Now, these concerns are valid, but because bowling averages have uncertainty that tends with the square root of wickets taken, these uncertainties get small fairly quickly. That said, as pointed out, comparing someone like McGrath, with 563 wickets, to someone like Cummins with 143 does run that concern.

Now, there are a number of ways to take into account this issue with uncertainty. One such method is to use bayesian inference. To do this, we need a prior distribution, which in this instance is the average distribution of bowlers playing test cricket. We need both a mean and a standard deviation for the two metrics used, these being bowling average and wickets per match. To find this, the same analysis was applied to set of all bowlers with at least 20 tests being one of the first four bowlers to bowl in an innings. This took into account the same era effects as before:

What Average WPM
Mean 29.80 3.083
Stdev 7.11 1.001

To make use of this, we need to make a few assumptions:

  1. All bowlers in the set have sufficiently large samples that the likelihood function for their averages behaves as a normal distribution.
  2. The samples for bowlers is large enough that wicket taking behaves as an exponential distribution, hence the standard deviation of the distribution of 'runs per wicket' is approximately the same as the average.
  3. The standard deviation for wickets per match is approximately 0.60 times the wickets per match value.

2 and 3 can be shown to be approximately true in general from surveys of player data (varies by about 10% player to player), while 1 is generally true just from the sample size used. The impact of breaking these assumptions is basically making the next step order of magnitude fiddlier, but doesn't impact the results to any great extent. The method that'll we'll be using is the standard for determining a posterior distribution's average for two normal distributions, breaking the assumptions makes it messier as we can't use that calculation anymore. The calculation itself is annoying to format on reddit, so I'll just post it as an image here. Here, mu represents the averages of the posterior (denoted such) and prior (denoted with a 0) as well as the average from the likelihood function (x-bar) and their respective standard deviations (sigma and sigma 0).

In any case, armed with this, we can use the players averages and the expected distributions of players to determine an average that we, in effect, have the evidence to claim. That is, the way to think about the numbers produced are to see them not as their actual averages, but rather, a value that we can confidently claim with the evidence given. If you've ever wanted to quantify that thought of "well, if a guy has 500 wickets at 25.00, and another has 100 wickets at 24.00, I'd go with the guy with 500 still", this is basically the formal way of doing that. Here, we'll be using

In any case, below is the new top 50, using those adjusted values. I've included the old rating for comparison sake. As would be expected, it has had a large impact on the likes of Cummins and Asif.

Rank Player Matches Wickets B-WPM B-Adj Old Rat B-Rat
1 SF Barnes (ENG) 27 189 5.455 18.97 0.6139 0.5363
2 Sir RJ Hadlee (NZ) 86 431 4.829 20.97 0.4910 0.4799
3 MD Marshall (WI) 81 376 4.506 19.69 0.4881 0.4784
4 GD McGrath (AUS) 124 563 4.458 19.75 0.4811 0.4751
5 DW Steyn (SA) 93 439 4.591 20.69 0.4796 0.4710
6 J Garner (WI) 58 259 4.314 20.24 0.4731 0.4616
7 DK Lillee (AUS) 70 355 4.840 22.73 0.4745 0.4615
8 PJ Cummins (AUS) 30 143 4.407 20.90 0.4835 0.4591
9 AA Donald (SA) 72 330 4.441 21.14 0.4681 0.4583
10 FS Trueman (ENG) 67 307 4.430 21.19 0.4677 0.4573
11 CEL Ambrose (WI) 98 405 4.071 19.96 0.4572 0.4517
12 Mohammad Asif (PAK) 23 106 4.229 21.46 0.4709 0.4439
13 AK Davidson (AUS) 44 186 4.082 20.82 0.4550 0.4428
14 K Rabada (SA) 43 197 4.358 22.43 0.4556 0.4408
15 Waqar Younis (PAK) 87 373 4.202 21.92 0.4443 0.4378
16 Imran Khan (PAK) 88 362 4.047 21.44 0.4401 0.4345
17 AV Bedser (ENG) 51 236 4.425 23.80 0.4436 0.4312
18 RJ Harris (AUS) 27 113 3.977 21.42 0.4487 0.4309
19 SM Pollock (SA) 108 421 3.859 21.14 0.4313 0.4273
20 CEH Croft (WI) 27 125 4.287 23.87 0.4452 0.4237
21 SR Clark (AUS) 24 94 3.761 21.02 0.4397 0.4230
22 MA Holding (WI) 60 249 4.050 22.71 0.4301 0.4223
23 Wasim Akram (PAK) 104 414 3.934 22.18 0.4253 0.4212
24 NAT Adcock (SA) 26 104 3.834 21.75 0.4357 0.4199
25 BA Reid (AUS) 27 113 3.977 23.04 0.4318 0.4154
26 PM Pollock (SA) 28 116 3.952 23.02 0.4296 0.4143
27 CA Walsh (WI) 132 519 3.898 22.93 0.4153 0.4123
28 MG Johnson (AUS) 73 313 4.188 24.93 0.4163 0.4099
29 AME Roberts (WI) 47 202 4.148 24.95 0.4175 0.4077
30 N Wagner (NZ) 48 206 4.145 25.17 0.4152 0.4058
31 VD Philander (SA) 64 224 3.473 21.15 0.4100 0.4052
32 MA Starc (AUS) 57 244 4.157 25.45 0.4120 0.4042
33 Mohammad Abbas (PAK) 21 80 3.665 22.52 0.4192 0.4034
34 JA Snow (ENG) 49 202 4.007 24.81 0.4101 0.4019
35 Shoaib Akhtar (PAK) 46 178 3.787 23.56 0.4085 0.4009
36 RR Lindwall (AUS) 61 228 3.688 23.06 0.4053 0.3999
37 JM Anderson (ENG) 156 600 3.821 24.02 0.4011 0.3989
38 IR Bishop (WI) 43 161 3.675 23.12 0.4062 0.3987
39 TM Alderman (AUS) 41 170 4.007 25.33 0.4072 0.3977
40 Fazal Mahmood (PAK) 34 139 3.937 25.34 0.4048 0.3942
41 WW Hall (WI) 48 192 3.902 25.33 0.3997 0.3925
42 MHN Walker (AUS) 34 138 3.914 25.80 0.3995 0.3895
43 JN Gillespie (AUS) 71 259 3.612 24.00 0.3919 0.3879
44 TA Boult (NZ) 67 267 3.914 26.04 0.3926 0.3877
45 JR Hazlewood (AUS) 51 195 3.754 24.99 0.3935 0.3876
46 CJ McDermott (AUS) 71 291 4.019 26.80 0.3921 0.3872
47 RGD Willis (ENG) 90 325 3.585 23.98 0.3897 0.3867
48 MG Hughes (AUS) 53 212 3.910 26.19 0.3925 0.3864
49 M Ntini (SA) 101 390 3.822 25.81 0.3878 0.3848
50 JL Pattinson (AUS) 21 81 3.700 25.33 0.3955 0.3822

Jimmy moves to the 12th XI!

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