LiveCodeBench, posterior accuracy ŝ & validity rate Z of two constraints

How accurate is ideal constrained generation? For each problem, the rollouts a potential accepts are exact samples from the constrained posterior; ŝ is the fraction of them that are correct, averaged one-problem-one-vote over the benchmark (0/0 := 0), with the fraction of problems with no accepted rollout and the validity rate Z. Two potentials: no-runtime-error (LCBRuntimeNoErrorPotential) and public-test (LCBPublicTestPotential), 12 models × 6 temperatures (71 cells, ~4.2M rollouts). This page previously headlined the pooled ratio Ŝ = ∑correct/∑valid (“skyline”); see Definitions.

On this page
  1. Definitions
  2. prior pass@1 vs macro posterior accuracy ŝ, per model
  3. posterior accuracy ŝ against temperature
  4. ŝ by model and temperature
  5. problems with no valid rollout
  6. Z, the validity rate (normalizing constant)
  7. pooled Ŝ (secondary)
  8. by difficulty, choose a model
  9. posterior accuracy ŝ against temperature
  10. ŝ by model and temperature
  11. problems with no accepted rollout
  12. Z, the acceptance rate (normalizing constant)
  13. pooled Ŝ (secondary)
  14. by difficulty, choose a model

Definitions

Two potentials, two constraints. Each rollout y for problem x defines a validity indicator φ(y); rejection sampling targets the posterior π(·|x) ∝ p0(·|x)·φ(·) — sample from the model, keep the valid ones. Correct = the LCB evaluator’s verdict over all tests (public + private).

Z(x) = Pr(y valid | x) ≈ Validx/N     s(x) := Pr(y correct | y valid, x) ≈ Correctx/Validx     Pr(y correct | x) = Z(x)·s(x)

Posterior accuracy over the benchmark (headline). Treating the benchmark as a sample of problems x ~ D, the number we want is the expected posterior accuracy of a new problem, s̄ := 𝔼x~D[ s(x) ], estimated by the macro estimator — one problem, one vote — with 0/0 := 0 for problems none of whose N rollouts is valid:

ŝ = meanx [ Correctx/Validx  if Validx > 0,  else 0 ]

ŝ is consistent for s̄. Each per-problem ratio is unbiased given at least one valid sample, so at finite N the only bias is the 0/0 := 0 convention, which pulls ŝ down by at most the fraction of zero-valid problems, reported next to every ŝ. (Dropping the zero-valid problems instead is biased too — a ratio of two unbiased estimators — and changes the population to “problems this model can make valid”; we show it only in the tables as ŝ+.) A fine-tuned or approximate sampler is scored by its macro pass@1, so ŝ is the comparable reference.

No-error potential (LCBRuntimeNoErrorPotential): φ = the code runs on the public inputs with no runtime error / timeout. A program that runs but answers wrongly is still valid.

Public-test potential (LCBPublicTestPotential): the strict constraint is “passes all public example tests”. Because the potential is soft (finite penalty per failed public test), every public-test section is indexed by k = the max number of failing public tests allowed: φk=1[n_failed≤k]. k=0 is the strict potential; raising k relaxes it, and at k=max#public-tests every rollout is accepted (Z=1, ŝ=pass@1). A correct solution passes every public test, so correct ⇒ φk for every k.

Nesting: correct ⇒ passes-all-public (k=0) ⇒ runs-no-error, hence pass@1 ≤ Zpublic ≤ Zno-error.

Why not pool? Earlier versions of this page reported the pooled ratio

Ŝ = (∑x Correctx) / (∑x Validx) = pass@1 / Z

Ŝ is a consistent estimate of a different quantity,

S̄ := 𝔼[ Z(x) s(x) ] / 𝔼[ Z(x) ] = s̄ + Cov(Z, s) / 𝔼[ Z(x) ]

a validity-weighted average: every valid rollout gets one vote, so problems the model already handles well (high Z) dominate, and problems with Z(x) = 0 have no weight at all. Because Z and s are positively correlated (problems that error more are also wrong more), Ŝ sits above s̄ — not through finite-sample bias but because it estimates the wrong thing. Ŝ is kept below as a secondary number because pass@1 = Z × Ŝ holds exactly on pooled estimates.

Why report this? ŝ is the accuracy of ideal constrained generation: if you could sample exactly from π (enforce the constraint and nothing else), this is how often the result would be correct — a reference for judging approximate inference methods (importance sampling, SMC, fine-tuning) that target the same π. Formerly called the “skyline” on this site. Shaded bands are 95% bootstrap CIs (2000 resamples of the problem set).

LiveCodeBench, 12 models × 6 temperatures (71 cells, ~4.2M rollouts, N = 100 rollouts per problem, 1 at t = 0); both potentials run literally (forkserver, 6 s per-test timeout). The instance with no public tests is excluded. Two cells (Llama 3.2 1B Instruct, t = 0.8 and 1.0) have pooled numbers only.

Posterior vs prior — what conditioning on validity buys

prior pass@1 vs macro posterior accuracy ŝ, per model

Conditioning on validity: the sample's code runs on the public inputs with no runtime error or timeout (wrong answers still count as valid) — the potential LCBRuntimeNoErrorPotential

x is the prior pass@1: the accuracy as sampled. y is the macro posterior accuracy ŝ = meanx Pr(correct | valid, x) (0/0 := 0): the accuracy of a sampler that draws exactly from the posterior the validity notion above defines, one problem one vote. Height above the diagonal is the gain; error bars are 95% bootstrap CIs (2000 resamples of the problem set) on both axes. Hovering a dot also shows two reference lines: the ray from the origin (its slope is the dot’s ŝ/pass@1 ratio) and the line through (1,1) (slope = the surviving-failure fraction).

Part 1 — no-error potential

posterior accuracy ŝ against temperature

ŝ = meanx Pr(correct | runs without error, x), 0/0 := 0. Wrong-but-running answers dilute it.

ŝ by model and temperature

Each cell: ŝ, its 95% bootstrap CI, and how many problems had no valid rollout among the N sampled (these enter ŝ as 0).

modelt=0t=0.2t=0.4t=0.6t=0.8t=1.0
Llama-3 8B0.108
[0.086, 0.132]
151/713 zero-valid
0.110
[0.090, 0.131]
12/713 zero-valid
0.099
[0.081, 0.118]
2/713 zero-valid
0.087
[0.071, 0.103]
1/713 zero-valid
0.066
[0.054, 0.079]
0/713 zero-valid
0.043
[0.034, 0.053]
1/713 zero-valid
Llama-3 8B Instruct0.164
[0.139, 0.192]
129/713 zero-valid
0.166
[0.141, 0.194]
27/713 zero-valid
0.164
[0.140, 0.190]
13/713 zero-valid
0.159
[0.137, 0.185]
6/713 zero-valid
0.151
[0.130, 0.175]
2/713 zero-valid
0.142
[0.121, 0.164]
1/713 zero-valid
Llama-3.1 8B0.102
[0.081, 0.126]
159/713 zero-valid
0.106
[0.086, 0.128]
17/713 zero-valid
0.099
[0.081, 0.118]
2/713 zero-valid
0.087
[0.071, 0.104]
0/713 zero-valid
0.068
[0.055, 0.082]
0/713 zero-valid
0.045
[0.036, 0.056]
0/713 zero-valid
Llama-3.1 8B Instruct0.191
[0.163, 0.222]
114/713 zero-valid
0.197
[0.172, 0.225]
5/713 zero-valid
0.196
[0.172, 0.221]
1/713 zero-valid
0.187
[0.165, 0.212]
3/713 zero-valid
0.172
[0.150, 0.195]
1/713 zero-valid
0.149
[0.129, 0.170]
1/713 zero-valid
Llama-3.2 1B0.015
[0.007, 0.025]
313/713 zero-valid
0.015
[0.008, 0.023]
33/713 zero-valid
0.014
[0.009, 0.020]
4/713 zero-valid
0.010
[0.006, 0.014]
0/713 zero-valid
0.007
[0.004, 0.010]
0/713 zero-valid
0.003
[0.002, 0.005]
0/713 zero-valid
Llama-3.2 1B Instruct0.062
[0.045, 0.080]
259/713 zero-valid
0.069
[0.054, 0.085]
13/713 zero-valid
0.064
[0.051, 0.079]
5/713 zero-valid
–––
Qwen2.5-Coder 3B0.220
[0.191, 0.251]
131/713 zero-valid
0.228
[0.200, 0.257]
14/713 zero-valid
0.224
[0.198, 0.250]
3/713 zero-valid
0.212
[0.188, 0.237]
0/713 zero-valid
0.182
[0.162, 0.204]
0/713 zero-valid
0.134
[0.117, 0.152]
0/713 zero-valid
Qwen2.5-Coder 3B Instruct0.238
[0.206, 0.272]
137/713 zero-valid
0.250
[0.222, 0.280]
9/713 zero-valid
0.251
[0.225, 0.280]
4/713 zero-valid
0.242
[0.216, 0.269]
1/713 zero-valid
0.231
[0.207, 0.257]
1/713 zero-valid
0.210
[0.186, 0.235]
0/713 zero-valid
Qwen2.5-Coder 7B0.279
[0.245, 0.313]
93/713 zero-valid
0.287
[0.256, 0.318]
5/713 zero-valid
0.283
[0.255, 0.312]
0/713 zero-valid
0.263
[0.236, 0.289]
0/713 zero-valid
0.228
[0.205, 0.252]
0/713 zero-valid
0.172
[0.153, 0.191]
0/713 zero-valid
Qwen2.5-Coder 7B Instruct0.349
[0.314, 0.386]
76/713 zero-valid
0.354
[0.321, 0.387]
13/713 zero-valid
0.350
[0.318, 0.382]
6/713 zero-valid
0.346
[0.315, 0.377]
3/713 zero-valid
0.337
[0.308, 0.367]
2/713 zero-valid
0.327
[0.298, 0.356]
0/713 zero-valid
DeepSeek-Coder 6.7B0.163
[0.136, 0.191]
86/713 zero-valid
0.168
[0.143, 0.194]
15/713 zero-valid
0.163
[0.139, 0.187]
2/713 zero-valid
0.153
[0.131, 0.176]
1/713 zero-valid
0.135
[0.116, 0.156]
1/713 zero-valid
0.106
[0.090, 0.123]
2/713 zero-valid
DeepSeek-Coder 6.7B Instruct0.201
[0.171, 0.231]
110/713 zero-valid
0.207
[0.179, 0.234]
9/713 zero-valid
0.201
[0.175, 0.227]
5/713 zero-valid
0.199
[0.174, 0.225]
2/713 zero-valid
0.194
[0.169, 0.219]
0/713 zero-valid
0.184
[0.161, 0.209]
0/713 zero-valid

problems with no valid rollout

Fraction of problems where none of the N rollouts ran without error. They contribute 0 to ŝ and bound its downward bias.

Z, the validity rate (normalizing constant)

Z = proportion of rollouts that run without error; falls toward t=1.0.

pooled Ŝ (secondary)

Ŝ = ∑correct / ∑valid = pass@1 / Z, the page’s former headline; estimates 𝔼[Z s]/𝔼[Z], not 𝔼[s].

modelt=0t=0.2t=0.4t=0.6t=0.8t=1.0
Llama-3 8B0.1380.1310.1190.1060.0850.063
Llama-3 8B Instruct0.2020.1990.1950.1890.1830.180
Llama-3.1 8B0.1320.1270.1190.1060.0880.068
Llama-3.1 8B Instruct0.2290.2240.2220.2160.2060.203
Llama-3.2 1B0.0270.0220.0180.0130.0090.005
Llama-3.2 1B Instruct0.0980.0950.088–0.0670.054
Qwen2.5-Coder 3B0.2730.2730.2690.2570.2270.190
Qwen2.5-Coder 3B Instruct0.2970.3000.2980.2890.2820.273
Qwen2.5-Coder 7B0.3210.3190.3150.2990.2710.240
Qwen2.5-Coder 7B Instruct0.3990.3940.3900.3870.3810.377
DeepSeek-Coder 6.7B0.1850.1870.1820.1730.1590.139
DeepSeek-Coder 6.7B Instruct0.2420.2340.2270.2270.2240.220

by difficulty, choose a model

No-error ŝ and Z split by problem difficulty for a single model. Shaded bands are 95% bootstrap CIs over that difficulty’s problems.

ŝ, zero-valid fraction, Z and pooled Ŝ by difficulty and temperature (selected model):

difficultymetrict=0t=0.2t=0.4t=0.6t=0.8t=1.0
easyŝ (macro)0.2980.3010.2740.2420.1850.122
zero-valid frac.0.1220.0080.0000.0000.0000.000
Z0.8780.8750.8630.8110.7210.494
Ŝ (pooled)0.3400.3230.2940.2600.1990.136
mediumŝ (macro)0.0220.0240.0190.0150.0100.006
zero-valid frac.0.2240.0220.0040.0000.0000.004
Z0.7730.7860.7700.7180.6120.372
Ŝ (pooled)0.0280.0290.0220.0180.0120.007
hardŝ (macro)0.0000.0000.0010.0000.0000.000
zero-valid frac.0.3030.0200.0050.0050.0000.000
Z0.6820.6810.6510.5710.4400.232
Ŝ (pooled)0.0000.0000.0010.0000.0010.000

Part 2 — public-test potential

Pick the acceptance threshold k (max public-test failures allowed); every plot and table in this part updates to that k. k=0 is the strict “pass all public tests” potential.

posterior accuracy ŝ against temperature

ŝ = meanx Pr(correct | accepted at threshold k, x), 0/0 := 0. At k=0 this is the strict public-test posterior accuracy — much higher than the no-error one.

ŝ by model and temperature

modelt=0t=0.2t=0.4t=0.6t=0.8t=1.0
Llama-3 8B0.1080.1870.2140.2280.2190.184
Llama-3 8B Instruct0.1640.2350.2710.2930.2880.294
Llama-3.1 8B0.1020.1880.2210.2350.2230.191
Llama-3.1 8B Instruct0.1910.3150.3520.3540.3510.335
Llama-3.2 1B0.0150.0430.0640.0700.0580.037
Llama-3.2 1B Instruct0.0620.1610.189–––
Qwen2.5-Coder 3B0.2200.3410.3780.3960.3830.355
Qwen2.5-Coder 3B Instruct0.2380.3670.4040.4090.4130.398
Qwen2.5-Coder 7B0.2790.4020.4550.4540.4490.398
Qwen2.5-Coder 7B Instruct0.3490.4490.4760.4920.4960.498
DeepSeek-Coder 6.7B0.1630.2690.3120.3260.3350.310
DeepSeek-Coder 6.7B Instruct0.2010.3160.3590.3780.3830.384

problems with no accepted rollout

Fraction of problems where none of the N rollouts is accepted at threshold k. At k=0 these are the problems for which the model never passes all public tests in N tries; they enter ŝ as 0.

Z, the acceptance rate (normalizing constant)

Z = proportion of rollouts accepted at threshold k (k=0: pass all public tests). Rises toward 1 as k grows.

pooled Ŝ (secondary)

Ŝ = ∑correct / ∑accepted = pass@1 / Zk, the former headline.

modelt=0t=0.2t=0.4t=0.6t=0.8t=1.0
Llama-3 8B0.7060.6940.6760.6940.6860.723
Llama-3 8B Instruct0.6840.6620.6700.6750.6850.697
Llama-3.1 8B0.6700.6620.6730.6860.7070.734
Llama-3.1 8B Instruct0.7160.7290.7420.7580.7700.789
Llama-3.2 1B0.5790.5900.5630.5010.4810.412
Llama-3.2 1B Instruct0.7460.6680.669–0.6820.692
Qwen2.5-Coder 3B0.7660.7720.7770.7890.7930.825
Qwen2.5-Coder 3B Instruct0.7830.7750.7840.7880.7950.805
Qwen2.5-Coder 7B0.7830.7990.8080.8160.8250.844
Qwen2.5-Coder 7B Instruct0.8140.8050.8050.8080.8090.815
DeepSeek-Coder 6.7B0.7580.7350.7340.7320.7430.754
DeepSeek-Coder 6.7B Instruct0.8120.7790.7750.7770.7840.796

by difficulty, choose a model

Public-test ŝ and Z split by difficulty for a single model, at the selected k. Use both selectors; the plots and table update together.

ŝ, zero-valid fraction, Z and pooled Ŝ by difficulty and temperature (selected model & k):

difficultymetrict=0t=0.2t=0.4t=0.6t=0.8t=1.0
easyŝ (macro)0.2980.4960.5590.5990.5790.493
zero-valid frac.0.6760.3400.2350.1810.1890.286
Z0.3190.3120.2880.2370.1690.081
Ŝ (pooled)0.9340.9050.8810.8890.8510.835
mediumŝ (macro)0.0220.0520.0680.0710.0590.048
zero-valid frac.0.9030.7080.5600.5050.5420.722
Z0.0980.0880.0730.0550.0340.012
Ŝ (pooled)0.2220.2560.2300.2310.2200.239
hardŝ (macro)0.0000.0030.0040.0010.0110.002
zero-valid frac.0.9700.8130.7070.6770.6870.848
Z0.0300.0370.0380.0290.0170.004
Ŝ (pooled)0.0000.0080.0130.0070.0150.024