Reinforcement learning (RL) plays a central role in improving the reasoning and alignment of large language models, yet its efficiency critically depends on how training data are selected. Existing online selection strategies predominantly rely on difficulty-based heuristics, favouring datapoints with intermediate success rates, implicitly equating difficulty with informativeness and neglecting epistemic uncertainty arising from limited evidence. We introduce InSight, an INformation-guided data SamplInG metHod for RL Training, grounded in a weighted mutual information objective. By modeling data outcomes with Bayesian latent success rates, we show that expected uncertainty reduction decomposes into complementary difficulty- and evidence-dependent components, revealing a fundamental limitation of difficulty-only selection. Leveraging this observation, InSight constructs a stable acquisition score based on the mean belief of datapoints' success rather than noisy sampled outcomes, and naturally extends to multi-rollout settings common in reinforcement learning with verifiable rewards (RLVR). Extensive experiments demonstrate that InSight consistently achieves state-of-the-art performance and improves training efficiency, including a +1.41 average gain on Planning & Mathmatics benchmarks, +1.01 improvement on general reasoning, and up to ~2.2x acceleration, with negligible additional computational overhead.
Figures & tables
Figure 1: Overview of the InSight pipeline. InSight maintains a Bayesian belief over data success rates, scores candidate datapoints using Weighted Mutual Information (WMI), and selects the top- M datapoints for RL training. Observed rewards update the posterior beliefs, enabling adaptive data selection that jointly accounts for data difficulty and accumulated evidence, unlike difficulty-only heuristics.
Figure 2: Expected variance reduction as a function of prior mean ϕˉτ and accumulated evidence n . While difficulty-based heuristics focus solely on ϕˉτ≈0.5 , the expected uncertainty reduction decays rapidly with evidence, revealing a fundamental limitation of difficulty-only selection.
Figure 3: Weighted functions w(ϕˉ) under different η,μ .
Models
Methods
CountDown
AIME24
AMC23
MATH500
Minerva.
Olympiad.
Avg.
Random
71.57
10.41
43.90
71.30
21.60
34.20
42.16
Qwen3-0.6B
MoPPS
76.28
10.83
44.16
70.60
21.60
34.25
42.95
Inverse-Evidence
72.13
10.60
42.50
71.80
21.70
34.80
42.25
InSight (Ours)
76.70 (5.13 ↑ )
11.90 (1.49 ↑ )
44.30 (0.40 ↑ )
71.75 (0.45 ↑ )
21.94 (0.34 ↑ )
34.80 (0.60 ↑ )
43.56 (1.40 ↑ )
Random
84.90
51.45
78.01
91.22
41.13
56.24
67.16
Qwen3-4B
MoPPS
87.80
50.00
77.41
90.82
41.59
56.45
67.35
Table 1: Evaluation results across planning and mathematics benchmarks. Accuracy is computed as the average pass@1 over 16 independent generations per problem. Bold indicates the best results, and gray denotes the oracle baseline. ↑(↓) indicates the improvement(degradation) compared to the Random baseline.
Models
Methods
MMLU
GPQA
Avg.
Humanities
Other
Social-Sci.
STEM
Random
38.83
47.22
52.32
40.95
26.34
41.13
Qwen3-0.6B
MoPPS
39.17
47.12
51.12
38.69
27.90
40.80
Inverse-Evidence
38.55
45.19
49.76
36.95
29.46
39.98
InSight (Ours)
39.21 (0.38 ↑ )
47.34 (0.12 ↑ )
52.84 (0.52 ↑ )
41.80 (0.85 ↑ )
29.50 (3.16 ↑ )
42.14 (1.01 ↑ )
Random
48.63
60.41
64.09
53.47
30.20
51.36
Table 2: Evaluation results across general-reasoning benchmarks, via LM-Evaluation-Harness framework. Bold indicates the best results. ↑ indicates the improvement compared to the Random baseline.
Figure 4: Performance comparisons among different methods on the Countdown task. Our proposed InSight outperforms the existing SOTA ( MoPPS ) and other baselines in both training efficiency and performance.
Reinforcement learning studies how agents learn sequential decisions from rewards and interaction, balancing exploration, performance, safety, and adaptation.