Bravo, Cristián
Are causal effect estimations enough for optimal recommendations under multitreatment scenarios?
Alfonso-Sánchez, Sherly, Sendova, Kristina P., Bravo, Cristián
When making treatment selection decisions, it is essential to include a causal effect estimation analysis to compare potential outcomes under different treatments or controls, assisting in optimal selection. However, merely estimating individual treatment effects may not suffice for truly optimal decisions. Our study addressed this issue by incorporating additional criteria, such as the estimations' uncertainty, measured by the conditional value-at-risk, commonly used in portfolio and insurance management. For continuous outcomes observable before and after treatment, we incorporated a specific prediction condition. We prioritized treatments that could yield optimal treatment effect results and lead to post-treatment outcomes more desirable than pretreatment levels, with the latter condition being called the prediction criterion. With these considerations, we propose a comprehensive methodology for multitreatment selection. Our approach ensures satisfaction of the overlap assumption, crucial for comparing outcomes for treated and control groups, by training propensity score models as a preliminary step before employing traditional causal models. To illustrate a practical application of our methodology, we applied it to the credit card limit adjustment problem. Analyzing a fintech company's historical data, we found that relying solely on counterfactual predictions was inadequate for appropriate credit line modifications. Incorporating our proposed additional criteria significantly enhanced policy performance.
Attention-based Dynamic Multilayer Graph Neural Networks for Loan Default Prediction
Zandi, Sahab, Korangi, Kamesh, Óskarsdóttir, María, Mues, Christophe, Bravo, Cristián
Whereas traditional credit scoring tends to employ only individual borrower- or loan-level predictors, it has been acknowledged for some time that connections between borrowers may result in default risk propagating over a network. In this paper, we present a model for credit risk assessment leveraging a dynamic multilayer network built from a Graph Neural Network and a Recurrent Neural Network, each layer reflecting a different source of network connection. We test our methodology in a behavioural credit scoring context using a dataset provided by U.S. mortgage financier Freddie Mac, in which different types of connections arise from the geographical location of the borrower and their choice of mortgage provider. The proposed model considers both types of connections and the evolution of these connections over time. We enhance the model by using a custom attention mechanism that weights the different time snapshots according to their importance. After testing multiple configurations, a model with GAT, LSTM, and the attention mechanism provides the best results. Empirical results demonstrate that, when it comes to predicting probability of default for the borrowers, our proposed model brings both better results and novel insights for the analysis of the importance of connections and timestamps, compared to traditional methods.
INFLECT-DGNN: Influencer Prediction with Dynamic Graph Neural Networks
Tiukhova, Elena, Penaloza, Emiliano, Óskarsdóttir, María, Baesens, Bart, Snoeck, Monique, Bravo, Cristián
Leveraging network information for predictive modeling has become widespread in many domains. Within the realm of referral and targeted marketing, influencer detection stands out as an area that could greatly benefit from the incorporation of dynamic network representation due to the ongoing development of customer-brand relationships. To elaborate this idea, we introduce INFLECT-DGNN, a new framework for INFLuencer prEdiCTion with Dynamic Graph Neural Networks that combines Graph Neural Networks (GNN) and Recurrent Neural Networks (RNN) with weighted loss functions, the Synthetic Minority Oversampling TEchnique (SMOTE) adapted for graph data, and a carefully crafted rolling-window strategy. To evaluate predictive performance, we utilize a unique corporate data set with networks of three cities and derive a profit-driven evaluation methodology for influencer prediction. Our results show how using RNN to encode temporal attributes alongside GNNs significantly improves predictive performance. We compare the results of various models to demonstrate the importance of capturing graph representation, temporal dependencies, and using a profit-driven methodology for evaluation.
Multi-Modal Deep Learning for Credit Rating Prediction Using Text and Numerical Data Streams
Tavakoli, Mahsa, Chandra, Rohitash, Tian, Fengrui, Bravo, Cristián
Knowing which factors are significant in credit rating assignment leads to better decision-making. However, the focus of the literature thus far has been mostly on structured data, and fewer studies have addressed unstructured or multi-modal datasets. In this paper, we present an analysis of the most effective architectures for the fusion of deep learning models for the prediction of company credit rating classes, by using structured and unstructured datasets of different types. In these models, we tested different combinations of fusion strategies with different deep learning models, including CNN, LSTM, GRU, and BERT. We studied data fusion strategies in terms of level (including early and intermediate fusion) and techniques (including concatenation and cross-attention). Our results show that a CNN-based multi-modal model with two fusion strategies outperformed other multi-modal techniques. In addition, by comparing simple architectures with more complex ones, we found that more sophisticated deep learning models do not necessarily produce the highest performance; however, if attention-based models are producing the best results, cross-attention is necessary as a fusion strategy. Finally, our comparison of rating agencies on short-, medium-, and long-term performance shows that Moody's credit ratings outperform those of other agencies like Standard & Poor's and Fitch Ratings.
Optimizing Credit Limit Adjustments Under Adversarial Goals Using Reinforcement Learning
Alfonso-Sánchez, Sherly, Solano, Jesús, Correa-Bahnsen, Alejandro, Sendova, Kristina P., Bravo, Cristián
Credit cards are an essential part of modern financial life; according to the Consumer Financial Protection Bureau (2021), 175 million North Americans, more than half of its population, own credit card products. On the other hand, the same cannot be said for developing countries; according to the World Bank, an average of only 55% of Latin Americans had a bank account in January 2020, and only approximately 20% have a credit card (World Economic Forum, 2022). However, companies that use financial technology, known as fintechs, have enabled digital financial services that can help the unbanked population overcome difficulties such as costs, geographical impediments, long waiting times, and lack of financial history in accessing traditional banking products (Khera, Ng, Ogawa, & Sahay, 2022; Rojas-Torres, Kshetri, Hanafi, & Kouki, 2021). The number of fintech companies in Latin America has risen rapidly, and their appearance has altered the behavior of traditional banks, which are now seeking innovation and changes to customercentered approaches (Vives, 2019) and have decided in some cases to create alliances with these new companies (Bejar et al., 2022). Because the financial industry is primarily based on information, financial process reports have been more easily transitioned to the digitization stage; this situation is in contrast with the consumer goods industry, which includes a physical element (Puschmann, 2017). In addition, emerging "super-apps", which are mobile applications that offer different services and products in the same environment (e.g., goods deliveries, social networks, and financial services), collect a large amount of alternative data (Siddiqi, 2017) that are generated by the use of the given application and are supplementary to the traditional financial data. Several researchers have found that the use of alternative information is valuable in the financial sector because it allows for improvement in the performance of some models; for instance, Roa et al. (2021) showed that the inclusion of variables such as the number of payments with errors and orders paid with the superapp's own credit cards can add significant predictive value in the problem of default prediction.
A transformer-based model for default prediction in mid-cap corporate markets
Korangi, Kamesh, Mues, Christophe, Bravo, Cristián
In this paper, we study mid-cap companies, i.e. publicly traded companies with less than US $10 billion in market capitalisation. Using a large dataset of US mid-cap companies observed over 30 years, we look to predict the default probability term structure over the medium term and understand which data sources (i.e. fundamental, market or pricing data) contribute most to the default risk. Whereas existing methods typically require that data from different time periods are first aggregated and turned into cross-sectional features, we frame the problem as a multi-label time-series classification problem. We adapt transformer models, a state-of-the-art deep learning model emanating from the natural language processing domain, to the credit risk modelling setting. We also interpret the predictions of these models using attention heat maps. To optimise the model further, we present a custom loss function for multi-label classification and a novel multi-channel architecture with differential training that gives the model the ability to use all input data efficiently. Our results show the proposed deep learning architecture's superior performance, resulting in a 13% improvement in AUC (Area Under the receiver operating characteristic Curve) over traditional models. We also demonstrate how to produce an importance ranking for the different data sources and the temporal relationships using a Shapley approach specific to these models.
Influencer Detection with Dynamic Graph Neural Networks
Tiukhova, Elena, Penaloza, Emiliano, Óskarsdóttir, María, Garcia, Hernan, Bahnsen, Alejandro Correa, Baesens, Bart, Snoeck, Monique, Bravo, Cristián
Leveraging network information for prediction tasks has become a common practice in many domains. Being an important part of targeted marketing, influencer detection can potentially benefit from incorporating dynamic network representation. In this work, we investigate different dynamic Graph Neural Networks (GNNs) configurations for influencer detection and evaluate their prediction performance using a unique corporate data set. We show that using deep multi-head attention in GNN and encoding temporal attributes significantly improves performance. Furthermore, our empirical evaluation illustrates that capturing neighborhood representation is more beneficial that using network centrality measures.
Deep residential representations: Using unsupervised learning to unlock elevation data for geo-demographic prediction
Stevenson, Matthew, Mues, Christophe, Bravo, Cristián
LiDAR (short for "Light Detection And Ranging" or "Laser Imaging, Detection, And Ranging") technology can be used to provide detailed three-dimensional elevation maps of urban and rural landscapes. To date, airborne LiDAR imaging has been predominantly confined to the environmental and archaeological domains. However, the geographically granular and open-source nature of this data also lends itself to an array of societal, organizational and business applications where geo-demographic type data is utilised. Arguably, the complexity involved in processing this multi-dimensional data has thus far restricted its broader adoption. In this paper, we propose a series of convenient task-agnostic tile elevation embeddings to address this challenge, using recent advances from unsupervised Deep Learning. We test the potential of our embeddings by predicting seven English indices of deprivation (2019) for small geographies in the Greater London area. These indices cover a range of socio-economic outcomes and serve as a proxy for a wide variety of downstream tasks to which the embeddings can be applied. We consider the suitability of this data not just on its own but also as an auxiliary source of data in combination with demographic features, thus providing a realistic use case for the embeddings. Having trialled various model/embedding configurations, we find that our best performing embeddings lead to Root-Mean-Squared-Error (RMSE) improvements of up to 21% over using standard demographic features alone. We also demonstrate how our embedding pipeline, using Deep Learning combined with K-means clustering, produces coherent tile segments which allow the latent embedding features to be interpreted.
Evolution of Credit Risk Using a Personalized Pagerank Algorithm for Multilayer Networks
Bravo, Cristián, Óskarsdóttir, María
In this paper we present a novel algorithm to study the evolution of credit risk across complex multilayer networks. Pagerank-like algorithms allow for the propagation of an influence variable across single networks, and allow quantifying the risk single entities (nodes) are subject to given the connection they have to other nodes in the network. Multilayer networks, on the other hand, are networks where subset of nodes can be associated to a unique set (layer), and where edges connect elements either intra or inter networks. Our personalized PageRank algorithm for multilayer networks allows for quantifying how credit risk evolves across time and propagates through these networks. By using bipartite networks in each layer, we can quantify the risk of various components, not only the loans. We test our method in an agricultural lending dataset, and our results show how default risk is a challenging phenomenon that propagates and evolves through the network across time.
Super-App Behavioral Patterns in Credit Risk Models: Financial, Statistical and Regulatory Implications
Roa, Luisa, Correa-Bahnsen, Alejandro, Suarez, Gabriel, Cortés-Tejada, Fernando, Luque, María A., Bravo, Cristián
In this paper we present the impact of alternative data that originates from an app-based marketplace, in contrast to traditional bureau data, upon credit scoring models. These alternative data sources have shown themselves to be immensely powerful in predicting borrower behavior in segments traditionally underserved by banks and financial institutions. Our results, validated across two countries, show that these new sources of data are particularly useful for predicting financial behavior in low-wealth and young individuals, who are also the most likely to engage with alternative lenders. Furthermore, using the TreeSHAP method for Stochastic Gradient Boosting interpretation, our results also revealed interesting non-linear trends in the variables originating from the app, which would not normally be available to traditional banks. Our results represent an opportunity for technology companies to disrupt traditional banking by correctly identifying alternative data sources and handling this new information properly. At the same time alternative data must be carefully validated to overcome regulatory hurdles across diverse jurisdictions.