Selection bias is a difficult yet widespread problem in causal discovery, occurring whenever non-random selection processes lead to data that is not representative of the underlying populations. Due to its practical importance, related works have been proposed to address the problem under local [Versteeg et al., 2022] or interventional settings [Dai et al., 2025a], but general algorithms for observational data remain elusive. In this paper, we focus on truncated data (hard selection), and provide a general result for Additive Noise Models (ANM). We show that score-based methods are a surprisingly suitable candidate due to a special property of the score function (∇logp(x)): deterministic truncation preserves both the score of the joint distribution as well as the Jacobian of the score. While established score-matching algorithms still fail in most settings, we actively leverage this observation to propose a new method for causal discovery that is robust under truncated data with ANMs. Overall, our approach offers a general, robust solution that is agnostic to external information about the selection process and still achieves comparable performance to the state-of-the-art approaches when selection is not present.
Figures & tables
ANM Assumption
LiNGAM
CAM-UV
SCORE
NoGAM
CHess (Ours)
Nonlinear Gaussian
Linear non-Gaussian
Nonlinear non-Gaussian
Hard Selection (Truncation)
∗
Table 1: Identifiability guarantees of causal discovery methods across ANM assumptions. denotes full DAG identifiability; denotes no guarantee. LiNGAM ( Shimizu et al., 2006 ; Shimizu et al., 2011 ) only deals with linear non-Gaussian ANMs, SCORE ( Rolland et al., 2022 ) requires nonlinear mechanisms with Gaussian noise. NoGAM ( Montagna et al., 2025 ) extends SCORE to arbitrary noise distributions. CAM-UV ( Maeda and Shimizu, 2021 ) additionally handles latent confounders under nonlinear separable (CAM) assumptions. SCORE can handle latent hard selection bias in both Gaussian and non-Gaussian cases, which is not discussed in the original paper but is one of the surprising findings in this work ( ∗ ) . Our method (CHess) is the only method that is resilient to hard selection under all the above ANMs. Linear Gaussian models are known to be not identifiable beyond the Markov equivalence class ( Peters and Bühlmann, 2014 ) thus omitted in the table.
Figure 1: In the subgraph, the sink node Xc is only d-connected to its own noise Nc after conditioning on X\PAc , while Xp is d-connected to Np and Nc after conditioning on X\PAp∪X\CHp .
Setting
Sink rank
Non-sink rank
Gap
Linear Gaussian
0
0
0 (not identifiable)
Linear non-Gaussian
1
≥2
≥1
Nonlinear Gaussian
0
≥1
≥1
Nonlinear non-Gaussian
1
≥2
≥1
Table 2: Rank of M_{i}^{\mathrm{cond}}{\color[rgb]{0,0,0}(z)} for sink vs. non-sink nodes across different ANM settings.
d=5 , gumbel
d=10 , gumbel
fraction
ρ=1.0
ρ=0.1
ρ=0.05
ρ=1.0
ρ=0.1
ρ=0.05
SCORE
0.57 ( ± 0.25)
0.37 ( ± 0.17)
0.41 ( ± 0.14)
0.65 ( ± 0.12)
0.46 ( ± 0.11)
0.45 ( ± 0.10)
DAS
0.57 ( ± 0.25)
0.37 ( ± 0.17)
0.41 ( ± 0.14)
0.66 ( ± 0.11)
0.48 ( ± 0.12)
0.49 ( ± 0.10)
NoGAM
0.81 ( ± 0.21)
0.40 ( ± 0.16)
0.40 ( ± 0.14)
0.78 ( ± 0.16)
0.47 ( ± 0.14)
0.45 ( ± 0.11)
CAM
0.31 ( ± 0.20)
0.18 ( ± 0.14)
0.19 ( ± 0.12)
0.23 ( ± 0.08)
0.22 ( ± 0.11)
0.19 ( ± 0.12)
DirectLiNGAM
0.99 ( ± 0.03)
0.64 ( ± 0.14)
0.65 ( ± 0.16)
0.98 ( ± 0.03)
0.56 ( ± 0.05)
0.54 ( ± 0.07)
Table 3: F1 (Arrow) for Linear-nG (gumbel), d=5 and d=10
Method
ρ=1 ( n=373 )
ρ=0.1
SCORE
0.28 ( ± 0.05)
0.29 ( ± 0.05)
DAS
0.19 ( ± 0.10)
0.23 ( ± 0.08)
NoGAM
0.29 ( ± 0.04)
0.30 ( ± 0.06)
CAM
0.40 ( ± 0.08)
0.28 ( ± 0.09)
PC
0.25 ( ± 0.09)
0.23 ( ± 0.07)
FCI
0.13 ( ± 0.04)
0.14 ( ± 0.11)
Table 4: F1 (Arrow) on Sachs Dataset for ρ=1 (downasmpled) and ρ=0.1
Appendix figures & tables20 assets
Supplementary material from the paper’s appendix.
Appendix
Setting
sink rank
Non-sink rank
Gap
Linear + Gaussian
1
1
0 (not identifiable)
Linear + non-Gaussian
1
≥1+∣\CHl∣
∣\CHj∣≥1
Nonlinear + Gaussian
≤∣\PAl∣+1
≤∣\PAl∣+∣\CHl∣+1
∣\PAj∣+∣\CHj∣−∣\PAl∣
Nonlinear + non-Gaussian
≤∣\PAl∣+1
≤∣\PAl∣+∣\CHl∣+1
∣\PAj∣+∣\CHj∣−∣\PAl∣
Appendix
Table 5: Rank of Mj for sink vs. non-sink nodes across different ANM settings.
True
Estimated
Adjacency
Arrowhead
a←b
a←b
TP
TP, TN
a→b
TP
FP, FN
a — b
TP
FN
ab
FN
FN
ab
a←b
FP
FP
a→b
FP
FP
Appendix
Table 6: Metrics used for evaluation. Precision=TP/(TP+FP), Recall=TP/(TP+FN).
Oregon State University, Causal Intelligence and Reasoning Lab, Corvallis, USA · RIKEN Advanced Intelligence Project, Causal Inference Team, Tokyo, Japan · The University of Osaka, Reasoning for Intelligence Department, Osaka, Japan +1
Department of Statistics Seoul National University, Korea · Interdisciplinary Program in Artificial Intelligence; Institute for Data Innovation in Science, Seoul National University, Korea