Diagnosis
Extending Causal Models from Machines into Humans
Kacianka, Severin, Ibrahim, Amjad, Pretschner, Alexander, Trende, Alexander, Lüdtke, Andreas
Causal Models are increasingly suggested as a means to reason about the behavior of cyber-physical systems in socio-technical contexts. They allow us to analyze courses of events and reason about possible alternatives. Until now, however, such reasoning is confined to the technical domain and limited to single systems or at most groups of systems. The humans that are an integral part of any such socio-technical system are usually ignored or dealt with by "expert judgment". We show how a technical causal model can be extended with models of human behavior to cover the complexity and interplay between humans and technical systems. This integrated socio-technical causal model can then be used to reason not only about actions and decisions taken by the machine, but also about those taken by humans interacting with the system. In this paper we demonstrate the feasibility of merging causal models about machines with causal models about humans and illustrate the usefulness of this approach with a highly automated vehicle example.
Efficient Identification in Linear Structural Causal Models with Instrumental Cutsets
Kumor, Daniel, Chen, Bryant, Bareinboim, Elias
One of the most common mistakes made when performing data analysis is attributing causal meaning to regression coefficients. Formally, a causal effect can only be computed if it is identifiable from a combination of observational data and structural knowledge about the domain under investigation (Pearl, 2000, Ch. 5). Building on the literature of instrumental variables (IVs), a plethora of methods has been developed to identify causal effects in linear systems. Almost invariably, however, the most powerful such methods rely on exponential-time procedures. In this paper, we investigate graphical conditions to allow efficient identification in arbitrary linear structural causal models (SCMs). In particular, we develop a method to efficiently find unconditioned instrumental subsets, which are generalizations of IVs that can be used to tame the complexity of many canonical algorithms found in the literature. Further, we prove that determining whether an effect can be identified with TSID (Weihs et al., 2017), a method more powerful than unconditioned instrumental sets and other efficient identification algorithms, is NP-Complete. Finally, building on the idea of flow constraints, we introduce a new and efficient criterion called Instrumental Cutsets (IC), which is able to solve for parameters missed by all other existing polynomial-time algorithms.
What Is A Decision Tree?
A decision tree is a useful machine learning algorithm used for both regression and classification tasks. The name "decision tree" comes from the fact that the algorithm keeps dividing the dataset down into smaller and smaller portions until the data has been divided into single instances, which are then classified. If you were to visualize the results of the algorithm, the way the categories are divided would resemble a tree and many leaves. That's a quick definition of a decision tree, but let's take a deep dive into how decision trees work. Having a better understanding of how decision trees operate, as well as their use cases, will assist you in knowing when to utilize them during your machine learning projects.
On EducationMachine Learning Advanced: Decision Trees in Python - CouponED
The course is created on the basis of three pillars of learning: Know (Study) Do (Practice) Review (Self feedback) Know We have created a set of concise and comprehensive videos to teach you all the Excel related skills you will need in your professional career. Do With each lecture, we have provide a practice sheet to complement the learning in the lecture video. These sheets are carefully designed to further clarify the concepts and help you with implementing the concepts on practical problems faced on-the-job. Review Check if you have learnt the concepts by comparing your solutions provided by us. Ask questions in the discussion board if you face any difficulty.
Gini Index For Decision Trees
Decision trees are often used while implementing machine learning algorithms. The hierarchical structure of a decision tree leads us to the final outcome by traversing through the nodes of the tree. Each node consists of an attribute or feature which is further split into more nodes as we move down the tree. But how do we decide which attribute/feature should be placed at the root node, which features will act as internal nodes or leaf nodes? To decide this, and how to split the tree, we use splitting measures like Gini Index, Information Gain, etc.
Decision Tree Classifier from Scratch: Classifying Student's Knowledge Level
In simple words, Decision Tree Classifier is a Supervised Machine learning algorithm which is used for supervised classification problems. Under the hood in decision tree, each node asks a True or False question about one of the features and moves left or right with respect to the decision. You can learn more about Decision Tree from here. We are going to use a Machine Learning algorithms to find the patterns on the historical data of the students and classify their knowledge level, and for that we are going to write our own simple Decision Tree Classifier from scratch by using Python Programming Language. Though i am going to explain everything along the way, it will not be a basic level explanation.
Measurement Dependence Inducing Latent Causal Models
Markham, Alex, Grosse-Wentrup, Moritz
We consider the task of causal structure learning over measurement dependence inducing latent (MeDIL) causal models. We show that this task can be framed in terms of the graph theoretical problem of finding edge clique covers, resulting in a simple algorithm for returning minimal MeDIL causal models (minMCMs). This algorithm is non-parametric, requiring no assumptions about linearity or Gaussianity. Furthermore, despite rather weak assumptions about the class of MeDIL causal models, we show that minimality in minMCMs implies three rather specific and interesting properties: first, minMCMs provide lower bounds on (i) the number of latent causal variables and (ii) the number of functional causal relations that are required to model a complex system at any level of granularity; second, a minMCM contains no causal links between the latent variables; and third, in contrast to factor analysis, a minMCM may require more latent than measurement variables.
Gradient Boosted Decision Tree Neural Network
Saberian, Mohammad, Delgado, Pablo, Raimond, Yves
In this paper we propose a method to build a neural network that is similar to an ensemble of decision trees. We first illustrate how to convert a learned ensemble of decision trees to a single neural network with one hidden layer and an input transformation. We then relax some properties of this network such as thresholds and activation functions to train an approximately equivalent decision tree ensemble. The final model, Hammock, is surprisingly simple: a fully connected two layers neural network where the input is quantized and one-hot encoded. Experiments on large and small datasets show this simple method can achieve performance similar to that of Gradient Boosted Decision Trees.
Counterfactual diagnosis
Richens, Jonathan G., Lee, Ciaran M., Johri, Saurabh
Causal knowledge is vital for effective reasoning in science and medicine. In medical diagnosis for example, a doctor aims to explain a patient's symptoms by determining the diseases causing them. However, all previous approaches to Machine-Learning assisted diagnosis, including Deep Learning and model-based Bayesian approaches, learn by association and do not distinguish correlation from causation. Here, we propose a new diagnostic algorithm based on counterfactual inference which captures the causal aspect of diagnosis overlooked by previous approaches. Using a statistical disease model, which describes the relations between hundreds of diseases, symptoms and risk factors, we compare our counterfactual algorithm to the standard Bayesian diagnostic algorithm, and test these against a cohort of 44 doctors. We use 1763 clinical vignettes created by a separate panel of doctors to benchmark performance. Each vignette provides a non-exhaustive list of symptoms and medical history simulating a single presentation of a disease. The algorithms and doctors are tasked with determining the underlying disease for each vignette from symptom and medical history information alone. While the Bayesian algorithm achieves the accuracy comparable to the average doctor, placing in the top 49\% of doctors in our cohort, our counterfactual algorithm places in the top 20\% of doctors, achieving expert clinical accuracy. Our results demonstrate the advantage of counterfactual over associative reasoning in a complex real-world task, and show that counterfactual reasoning is a vital missing ingredient for applying machine learning to medical diagnosis.
Isolation and Localization of Unknown Faults Using Neural Network-Based Residuals
Localization of unknown faults in industrial systems is a difficult task for data-driven diagnosis methods. The classification performance of many machine learning methods relies on the quality of training data. Unknown faults, for example faults not represented in training data, can be detected using, for example, anomaly classifiers. However, mapping these unknown faults to an actual location in the real system is a non-trivial problem. In model-based diagnosis, physical-based models are used to create residuals that isolate faults by mapping model equations to faulty system components. Developing sufficiently accurate physical-based models can be a time-consuming process. Hybrid modeling methods combining physical-based methods and machine learning is one solution to design data-driven residuals for fault isolation. In this work, a set of neural network-based residuals are designed by incorporating physical insights about the system behavior in the residual model structure. The residuals are trained using only fault-free data and a simulation case study shows that they can be used to perform fault isolation and localization of unknown faults in the system.