Communicating Credit Risk with Large Language Models: Evaluation of Explanations from Standard and Alternative Data-Based Models
Organizations: Department of Statistical and Actuarial Sciences, Western University, London, Canada · Department of Computer Science, Western University, London, Canada · University of Southampton Business School, University of Southampton, Southampton, United Kingdom · Centre for Operational Research, Management Sciences and Information Systems, University of Southampton, Southampton, United Kingdom · School of Mathematical Sciences, University of Southampton, Southampton, United Kingdom · Department of Computer Science, Reykjavik University, Reykjavik, Iceland
Abstract
Credit decisioning is a high-stakes task in which model outputs must be accurate and explainable to support compliant decisions. Although modern credit risk models such as eXtreme Gradient Boosting (XGBoost) and Graph Neural Networks (GNNs) improve predictive performance, their explanations are often too technical for stakeholders creating communication gaps that can shape approvals, denials, and fairness judgments. We examine whether Large Language Models (LLMs) can serve as explanation layers that translate post-hoc explanation artefacts into stakeholder-appropriate risk narratives. Using Freddie Mac single-family loan-level data, we develop three pipelines: standard tabular (XGBoost + SHAP), and two with alternative data, a pure network-based (GNN + GNNExplainer), and a bimodal one (combining tabular and network data). We generate narratives with three LLM configurations: a small fine-tuned LLM (Gemma 3 4B), a large fine-tuned LLM (DeepSeek R1 70B), and a zero-shot commercial LLM (Gemini 2.5). Explanation quality is evaluated through automated checks across all pipelines and a human study of bimodal explanations comparing credit risk professionals and non-professionals on eight decision-relevant dimensions. We have three main findings. First, the pipeline accounts for higher variance in evidence-grounding scores than the language model, meaning that the binding constraint on explanation quality is the evidence representation, not the model used. Second, the explanation narratives reliably name the influential factors but are less reliable when stating the direction of influence, which may be consequential for adverse-action communication. Finally, professionals apply stricter evidentiary standards than non-professionals. We discuss implications for the governance of risk models, including deployment considerations and the value of domain-aligned LLMs in regulated credit settings.
Figures & tables
| LLM | Size | Fine-tuned | Deployment Mode | Source |
| Gemma 3 | Small (4B) | Yes | Open-source | Google DeepMind |
| DeepSeek R1 | Large (70B) | Yes | Open-source | DeepSeek AI |
| Gemini 2.5 | Undisclosed | No | API-based |
| Pipeline | Prompt Components |
| Tabular- based | Predicted outcome; top- SHAP feature attributions with descriptions; instructional step-by-step reasoning; guided subgoal structure; borrower-level counterfactual prompt; output format constraint. |
| Network- based | Predicted outcome; network connectivity analysis; instructional step-by-step reasoning for structural and relational reasoning; guided subgoal structure; network-level counterfactual prompt; output format constraint. |
| Bimodal | Predicted outcome; top- SHAP feature descriptions; GNNExplainer subgraph descriptions; combined instructional reasoning linking borrower and relational characteristics; combined borrower-level and network-level counterfactual prompt; disambiguation hint for conflicting contributions; output format constraint. |
| Metric | Acronym | CRP Wording | NCRP Wording |
| Understandability | UND | The explanation is easy to understand. | The explanation is easy to understand. |
| Trustworthiness | TRU | The explanation can be trusted because it presents sufficient and reliable evidence to support the loan decision. | I trust this explanation given by the system. |
| Insightfulness | INS | This explanation reveals insightful risk factors that influence loan decisions. | This explanation provides useful insight into why the decision was made. |
| Satisfaction | SAT | The level of detail satisfies my expectations for a risk assessment. | I am satisfied with how the explanation addressed my concerns about the decision. |
| Confidence | CON | This explanation increases my confidence for loan approval/denial. | I am confident in the explanation provided for the system’s decision. |
| Convincingness | CVN | The justification is convincing and argues for the decision using well-weighted risk evidence. | The explanation is convincing and makes the decision seem reasonable. |
| Pipeline | LLM | TFC | TDC | NFC | NDC |
| Tabular- based | Gemma 3 | 3.77 0.12 | 3.68 0.15 | 1.73 0.09 | 2.14 0.17 |
| DeepSeek R1 | 4.35 0.10 | 3.48 0.13 | 1.58 0.10 | 1.91 0.17 | |
| Gemini 2.5 | 3.91 0.11 | 3.94 0.15 | 1.90 0.09 | 2.42 0.15 | |
| Network- based | Gemma 3 | 1.02 0.03 | 1.10 0.07 | 4.83 0.07 | 3.20 0.09 |
| DeepSeek R1 | 1.00 0.00 | 1.15 0.10 | 4.46 0.11 | 3.22 0.09 | |
| Gemini 2.5 | 1.00 0.00 | 1.01 0.02 | 4.88 0.07 | 2.89 0.10 |
| Metric | ||||||
| TFC | 328.96 | 0.391 | 11.81 | 0.014 | 10.04 | 0.024 |
| TDC | 299.02 | 0.352 | 26.08 | 0.031 | 22.07 | 0.052 |
| NFC | 354.27 | 0.377 | 62.95 | 0.067 | 21.66 | 0.046 |
| NDC | 39.19 | 0.069 | 28.94 | 0.051 | 11.63 | 0.041 |
| Metric | Gemma 3 | DeepSeek R1 | Gemini 2.5 |
| UND | 4.65 0.14 | 4.24 0.23 | 4.41 0.19 |
| TRU | 4.23 0.21 | 3.93 0.25 | 3.98 0.22 |
| INS | 4.09 0.25 | 3.78 0.25 | 3.88 0.23 |
| SAT | 3.97 0.24 | 3.75 0.29 | 3.57 0.27 |
| CON | 4.10 0.22 | 3.70 0.27 | 3.87 0.24 |
| CVN | 4.08 0.22 | 3.64 0.29 | 3.74 0.25 |
| Metric | Gemma 3 | DeepSeek R1 | Gemini 2.5 |
| UND | 4.36 0.11 | 4.22 0.15 | 4.18 0.17 |
| TRU | 4.24 0.11 | 4.19 0.14 | 4.01 0.16 |
| INS | 4.11 0.13 | 4.03 0.15 | 4.06 0.16 |
| SAT | 4.08 0.14 | 4.12 0.14 | 4.01 0.17 |
| CON | 4.24 0.12 | 4.17 0.15 | 4.11 0.16 |
| CVN | 4.14 0.13 | 4.01 0.15 | 4.04 0.16 |
| CRPs | NCRPs | |||||
| Metric | Gemma 3 | DeepSeek R1 | Gemini 2.5 | Gemma 3 | DeepSeek R1 | Gemini 2.5 |
| UND | 4.05 (0.87) | 3.90 (0.88) | 3.94 (0.88) | 4.10 (0.76) | 3.78 (1.04) | 4.07 (0.85) |
| TRU | 4.17 (0.82) | 3.92 (1.00) | 3.68 (1.05) | 4.30 (0.60) | 4.01 (0.73) | 4.07 (0.78) |
| INS | 4.31 (0.82) | 3.77 (1.08) | 3.68 (0.99) | 4.39 (0.55) | 4.14 (0.67) | 4.07 (0.88) |
| SAT | 4.40 (0.67) | 3.81 (1.03) | 3.65 (0.93) | 4.38 (0.62) | 4.16 (0.71) | 4.09 (0.79) |
| CON | 4.35 (0.71) | 3.62 (1.16) | 3.68 (0.92) | 4.36 (0.58) | 4.11 (0.72) | 4.15 (0.83) |
| CRPs | NCRPs | |||||||
| Metric | Mean diff. | SD diff. | Mean diff. | SD diff. | ||||
| UND | 0.050 | 0.468 | 1.000 | 0.681 | 0.121 | 0.583 | 1.000 | 0.733 |
| TRU | 0.350 | 0.489 | 0.250 | 0.250 | 0.075 | 0.657 | 1.000 | 0.765 |
| INS | 0.150 | 0.648 | 1.000 | 0.732 | 0.045 | 0.510 | 1.000 | 0.765 |
| SAT | 0.250 | 0.635 | 1.000 | 0.517 | 0.288 | 0.455 | 0.722 | 0.413 |
| CON | 0.250 | 0.687 | 1.000 | 0.517 | 0.150 | 0.555 | 1.000 | 0.733 |
| Component | Variance | Share (%) |
| Participants (leniency/strictness) | 0.507 | 46.3 |
| Explanation cases (LLM instance) | 0.110 | 10.0 |
| Residual | 0.478 | 43.7 |
| Category | Feature | Description |
| Sentiment | sentiment_polarity | TextBlob polarity score (negative to positive) |
| sentiment_subjectivity | TextBlob subjectivity (objective to subjective) | |
| vader_compound | VADER composite sentiment score | |
| vader_pos | VADER positive sentiment proportion | |
| vader_neg | VADER negative sentiment proportion | |
| vader_neu | VADER neutral sentiment proportion |
Appendix figures & tables11 assets
Supplementary material from the paper’s appendix.
Appendix
| Feature | Description |
| fico | FICO credit score at origination |
| dti | Original debt-to-income ratio |
| ltv | Original loan-to-value ratio |
| mi_pct | Mortgage insurance percentage |
| orig_upb | Original unpaid principal balance |
| loan_term | Original term of the loan in months |
| Component | Concrete instantiation |
|---|---|
| 1) Predicted outcome | Prediction: Loan 31780 default probability . Actual outcome: default. |
| 2) Top- SHAP feature attributions with descriptions | Evidence (top- SHAP; top-3 shown): • cnt_borr (SHAP:+0.4362): pushed toward default • fico (SHAP:–0.2609): pushed toward no default • dti (SHAP:+0.0799): pushed toward default (Full top- list is passed to the LLM; only top-3 shown here.) Feature descriptions: cnt_borr = number of borrowers; fico = credit score; dti = debt-to-income ratio. |
| 3–4) Instructional reasoning + guided subgoals | Instructions (follow in order): 1. Explain the predicted outcome in plain language. 2. Use the SHAP ordering; explain each listed factor: what it is, whether it increases/decreases risk, and why it matters to lenders. 3. Combine factors into a short overall justification. Constraints: borrower-facing language; do not mention SHAP/models/algorithms; reference only evidence-block factors; neutral tone; short sentences. |
| 5) Borrower-level counterfactual prompt | Counterfactual guidance: Provide two realistic improvement steps tied to the risk-increasing factors (positive SHAP values). Use cautious phrasing (e.g., “If you were able to…, this would likely improve…”). |
| 6) Output format constraint | Format: No bullet points in the final answer. End with one sentence summarising the main drivers. |
| Component | Concrete instantiation |
|---|---|
| 1) Predicted outcome | Prediction: Loan 2885 no-default probability . Actual outcome: no default. |
| 2) Network connectivity analysis | Evidence (GNNExplainer summary; top-3 shown): • Top node features (importance scores): – fico (0.6967) – if_corr (0.6736) – ltv (0.3349) • Top edge connections: – Geographic area connection (Loan 2733 2885, cluster size 75): impact 0.2380 – Area-provider cluster connection (Loan 2622 2885, cluster size 9): impact 0.2314 – Same loan provider connection (Loan 2493 2885, cluster size 145): impact 0.2266 (Full lists are passed to the LLM; only top-3 shown here.) |
| 3–4) Instructional reasoning + guided subgoals | Instructions (follow in order): 1. Explain the predicted outcome in plain language. 2. Describe the strongest connections using the edge list and cluster sizes. 3. Explain (at a high level) why geographic/provider groupings may matter, without adding unverifiable claims. Constraints: focus on relational/context evidence; mention at least two connection types; do not introduce attributes not shown in the evidence block; neutral tone. |
| 5) Network-level counterfactual prompt | Counterfactual guidance: Provide one cautious “what-if” statement on how different relational patterns (e.g., fewer links to a given cluster) could change confidence; avoid implying control over other borrowers. |
| 6) Output format constraint | Format: Include at least one sentence referencing a connection type and a cluster size from the evidence list. End with a one-sentence summary. |
| Component | Concrete instantiation |
|---|---|
| 1) Predicted outcome | Prediction: Loan 1007 default probability . Actual outcome: default. |
| 2) Top- SHAP feature descriptions | Evidence (tabular SHAP; top-3 shown): • cnt_borr (SHAP= ): increases risk • dti (SHAP= ): increases risk • fico (SHAP= ): reduces risk (Full top- list is passed to the LLM; only top-3 shown here.) |
| 3) GNNExplainer subgraph descriptions | Evidence (network summary; compact subset shown): • Edge: Same provider connection (Loan 5021 1007, cluster size 12) • Edge: Area-provider cluster (Loan 2893 1007, cluster size 8) • Node: Loan 5021 (defaulted) identified as influential neighbour (Full subgraph/edge lists are passed to the LLM; only a compact subset shown here.) |
| 4) Combined instructional reasoning linking both modalities | Instructions (follow in order): 1. Explain the predicted outcome overall. 2. Explain the strongest tabular drivers first (SHAP ordering), then the strongest network drivers (edge types + cluster sizes). 3. Include one explicit linking sentence describing how borrower-level and relational signals combine. |
| 5) Combined borrower- and network-level counterfactual prompt | Counterfactual guidance: Provide two improvement suggestions: (i) one tied to a positive-SHAP tabular factor; (ii) one stated cautiously about relational context (how different clustering patterns could affect confidence). |
| 6) Disambiguation hint for conflicting contributions | Disambiguation rule: If tabular and network evidence point in different directions, acknowledge both and state that the assessment balances the signals, without adding new evidence. |
| Pipeline | LLM | Perplexity |
| Gemma 3 | 19.38 0.67 | |
| Tabular-based | DeepSeek R1 | 15.93 0.36 |
| Gemini 2.5 | 33.20 1.21 | |
| Gemma 3 | 21.09 0.59 | |
| Network-based | DeepSeek R1 | 20.06 0.54 |
| Gemini 2.5 | 28.96 0.72 |
| Effect | |||
| Pipeline | 18.34 | 0.010 | |
| LLM | 1302.39 | 0.687 | |
| Pipeline LLM | 68.85 | 0.073 |
| Pipeline | LLM | UND | TRU | INS | SAT | CON | CVN | COM | USB |
| Gemma 3 | 3.89 0.07 | 2.11 0.06 | 2.15 0.07 | 1.99 0.02 | 2.62 0.10 | 2.11 0.06 | 2.70 0.09 | 1.42 0.10 | |
| Tabular-based | DeepSeek R1 | 3.79 0.08 | 2.38 0.10 | 2.34 0.09 | 2.14 0.07 | 2.75 0.09 | 2.38 0.10 | 2.95 0.07 | 1.79 0.08 |
| Gemini 2.5 | 3.99 0.08 | 2.80 0.08 | 2.78 0.09 | 2.58 0.10 | 2.96 0.08 | 2.79 0.08 | 3.29 0.12 | 1.86 0.07 | |
| Gemma 3 | 3.62 0.10 | 1.97 0.03 | 1.98 0.03 | 1.96 0.04 | 2.15 0.08 | 1.97 0.03 | 2.78 0.08 | 1.12 0.06 | |
| Network-based | DeepSeek R1 | 2.98 0.03 | 1.77 0.08 | 1.81 0.08 | 1.57 0.10 | 1.91 0.06 | 1.77 0.08 | 2.02 0.04 | 1.00 0.00 |
| Gemini 2.5 | 2.80 0.08 | 1.40 0.10 | 1.55 0.10 | 1.29 0.09 | 1.78 0.08 | 1.41 0.10 | 1.90 0.07 | 1.00 0.00 |
| Pipeline | LLM | UND | TRU | INS | SAT | CON | CVN | COM | USB |
| Gemma 3 | 4.43 0.11 | 3.44 0.10 | 3.89 0.06 | 3.45 0.10 | 3.43 0.10 | 4.13 0.10 | 4.43 0.11 | 3.38 0.10 | |
| Tabular-based | DeepSeek R1 | 4.00 0.08 | 3.20 0.10 | 3.85 0.08 | 3.36 0.10 | 3.19 0.10 | 3.91 0.08 | 4.00 0.08 | 3.10 0.09 |
| Gemini 2.5 | 4.39 0.10 | 3.62 0.10 | 4.19 0.08 | 3.81 0.08 | 3.62 0.10 | 4.29 0.11 | 4.39 0.10 | 3.54 0.10 | |
| Gemma 3 | 3.97 0.07 | 2.97 0.07 | 3.68 0.11 | 3.02 0.06 | 2.97 0.07 | 3.86 0.07 | 3.97 0.07 | 2.97 0.07 | |
| Network-based | DeepSeek R1 | 3.63 0.10 | 2.64 0.10 | 2.91 0.06 | 2.65 0.10 | 2.64 0.10 | 3.02 0.06 | 3.63 0.10 | 2.41 0.10 |
| Gemini 2.5 | 3.09 0.08 | 2.04 0.06 | 2.45 0.10 | 2.04 0.06 | 2.04 0.06 | 2.93 0.06 | 3.09 0.08 | 2.02 0.06 |
| Metric | |||||||||
| UND | 471.115 | 0.517 | 51.290 | 0.105 | 54.234 | 0.198 | |||
| TRU | 288.654 | 0.396 | 0.575 | 0.5628 | 0.001 | 52.728 | 0.194 | ||
| INS | 260.980 | 0.373 | 3.884 | 0.0209 | 0.009 | 38.091 | 0.148 | ||
| SAT | 243.487 | 0.357 | 0.930 | 0.3951 | 0.002 | 78.371 | 0.263 | ||
| CON | 445.581 | 0.503 | 0.512 | 0.5996 | 0.001 | 22.268 | 0.092 | ||
| CVN | 279.329 | 0.389 | 0.574 | 0.5632 | 0.001 | 50.728 | 0.188 |
| Metric | |||||||||
| UND | 229.281 | 0.343 | 27.297 | 0.058 | 53.932 | 0.197 | |||
| TRU | 302.394 | 0.408 | 17.788 | 0.039 | 57.377 | 0.207 | |||
| INS | 685.194 | 0.609 | 54.104 | 0.110 | 123.595 | 0.260 | |||
| SAT | 503.172 | 0.534 | 16.600 | 0.036 | 72.315 | 0.248 | |||
| CON | 297.011 | 0.403 | 16.985 | 0.037 | 58.700 | 0.211 | |||
| CVN | 461.246 | 0.512 | 68.807 | 0.135 | 75.891 | 0.257 |