Performance Analysis
Why it's hard to design fair machine learning models
In this episode of the Data Show, I spoke with Sharad Goel, assistant professor at Stanford, and his student Sam Corbett-Davies. They recently wrote a survey paper, "A Critical Review of Fair Machine Learning," where they carefully examined the standard statistical tools used to check for fairness in machine learning models. It turns out that each of the standard approaches (anti-classification, classification parity, and calibration) has limitations, and their paper is a must-read tour through recent research in designing fair algorithms. We talked about their key findings, and, most importantly, I pressed them to list a few best practices that analysts and industrial data scientists might want to consider. Sam Corbett-Davies: The problem with many of the standard metrics is that they fail to take into account how different groups might have different distributions of risk.
ML Metrics: Sensitivity vs. Specificity - DZone AI
In this post, we will try and understand the concepts behind evaluation metrics such as sensitivity and specificity, which is used to determine the performance of the Machine Learning models. The post also describes the differences between sensitivity and specificity. The concepts have been explained using the model for predicting whether a person is suffering from a disease or not. Sensitivity is a measure of the proportion of actual positive cases that got predicted as positive (or true positive). Sensitivity is also termed as Recall.
What Really Matters with Machine Learning
History will look back on our time as the beginning of the artificial intelligence revolution. In 2017, artificial intelligences are beating us at Go, translating and inventing their own languages, helping us decide what to buy, writing for us, and composing music. Neural networks can even be used for image compression! As you might expect, the endpoint security industry is benefiting greatly from AI as we are using it for everything, from detecting threats to unusual network activity. However, sometimes the problem with a complex, new technology, apart from actually inventing and building it, is figuring out how to explain it to customers -- how does it work and why is it valuable.
Using Confusion Matrices to Quantify the Cost of Being Wrong
There are so many confusing and sometimes even counter-intuitive concepts in statistics. I mean, come on…even explaining the differences between Null Hypothesis and Alternative Hypothesis can be an ordeal. All I want to do is to understand and quantify the cost of my analytical models being wrong. For example, let's say that I'm a shepherd who has bad eyesight and have a hard time distinguishing between a wolf and a sheep dog. That's obviously a bad trait, because the costs of being wrong are very expensive: Okay, so I'm not a very good shepherd, but I am a very sophisticated shepherd and I've build a Neural Network application to distinguish a sheep dog from a wolf.
Cost-Sensitive Learning for Predictive Maintenance
Spiegel, Stephan, Mueller, Fabian, Weismann, Dorothea, Bird, John
In predictive maintenance, model performance is usually assessed by means of precision, recall, and F1-score. However, employing the model with best performance, e.g. highest F1-score, does not necessarily result in minimum maintenance cost, but can instead lead to additional expenses. Thus, we propose to perform model selection based on the economic costs associated with the particular maintenance application. We show that cost-sensitive learning for predictive maintenance can result in significant cost reduction and fault tolerant policies, since it allows to incorporate various business constraints and requirements.
Active Fairness in Algorithmic Decision Making
Noriega-Campero, Alejandro, Bakker, Michiel, Garcia-Bulle, Bernardo, Pentland, Alex
Society increasingly relies on machine learning models for automated decision making. Yet, efficiency gains from automation have come paired with concern for algorithmic discrimination that can systematize inequality. Substantial work in algorithmic fairness has surged, focusing on either post-processing trained models, constraining learning processes, or pre-processing training data. Recent work has proposed optimal post-processing methods that randomize classification decisions on a fraction of individuals in order to achieve fairness measures related to parity in errors and calibration. These methods, however, have raised concern due to the information inefficiency, intra-group unfairness, and Pareto sub-optimality they entail. The present work proposes an alternative active framework for fair classification, where, in deployment, a decision-maker adaptively acquires information according to the needs of different groups or individuals, towards balancing disparities in classification performance. We propose two such methods, where information collection is adapted to group- and individual-level needs respectively. We show on real-world datasets that these can achieve: 1) calibration and single error parity (e.g., equal opportunity); and 2) parity in both false positive and false negative rates (i.e., equal odds). Moreover, we show that, by leveraging their additional degree of freedom, active approaches can outperform randomization-based classifiers previously considered optimal, while also avoiding limitations such as intra-group unfairness.
Explainable Black-Box Attacks Against Model-based Authentication
Garcia, Washington, Choi, Joseph I., Adari, Suman K., Jha, Somesh, Butler, Kevin R. B.
Establishing unique identities for both humans and end systems has been an active research problem in the security community, giving rise to innovative machine learning-based authentication techniques. Although such techniques offer an automated method to establish identity, they have not been vetted against sophisticated attacks that target their core machine learning technique. This paper demonstrates that mimicking the unique signatures generated by host fingerprinting and biometric authentication systems is possible. We expose the ineffectiveness of underlying machine learning classification models by constructing a blind attack based around the query synthesis framework and utilizing Explainable-AI (XAI) techniques. We launch an attack in under 130 queries on a state-of-the-art face authentication system, and under 100 queries on a host authentication system. We examine how these attacks can be defended against and explore their limitations. XAI provides an effective means for adversaries to infer decision boundaries and provides a new way forward in constructing attacks against systems using machine learning models for authentication.
Comment on "DNA damage is a pervasive cause of sequencing errors, directly confounding variant identification"
Even if the 8-oxo-G artifacts are twice the context-specific background level (i.e., GIVG_T 2), this corresponds to only a 5 to 10% increase in the overall base-level error rate (summed over all sequence contexts; Figure 1, A to C), which is less than the intersample variability of error rates at a fixed oxoQ. A 5% increase in the base-level error rate results in a minor, if any, increase in false-positive mutation calls (Figure 1, E and F), because calling algorithms are designed to handle typical levels of sequencing error. Only at GIVG_T 5 (equivalent to oxoQ 35) do the additional errors from 8-oxo-G become comparable to the sum of all other errors and have an adverse impact on variant calling. The vast majority of samples in TCGA exhibit only minor 8-oxo-G damage that has minimal impact on mutation calling. Consequently, the claim that 73% of TCGA sequencing runs have extensive damage is misleading.
Unfolding Naive Bayes From Scratch
I have tried to keep things simple and in plain-English. The sole purpose is to deeply and clearly understand the working of a well know Text Classification ML Algorithm (Naïve Bayes) without being trapped in the gibberish mathematical jargon that is often used in the explanation of ML Algorithms which obviously lands you nowhere except for being relying on ML API's with almost zero understanding of how the things actually work! A complete clear picture of the Naïve Bayes ML Algorithm with all its mysterious mathematics demystified plus a concrete step taken forward in your ML voyage! The Grand Grand Grand Milestone # 3: The Testing Phase --Where Prediction Comes into the Play! Naive Bayes is one of the most common ML algorithms that is often used for the purpose of text classification.