She graduated from the NYC Data Science Academy 12 week full time Data Science Bootcamp program taking place between April 11th to July 1st, 2016. This post is based on her final class project - Capstone, due on the 12th week of the program. The original article can be found here. Have you ever seen a marketing ad for a movie and thought, wow I have to see that! Then you go see it, it's a great film, the actor roles are amazing, in your book it's won an Oscar, and it's not even nominated?

Mutual Information (MI) is often used for feature selection when developing classifier models. Estimating the MI for a subset of features is often intractable. We demonstrate, that under the assumptions of conditional independence, MI between a subset of features can be expressed as the Conditional Mutual Information (CMI) between pairs of features. But selecting features with the highest CMI turns out to be a hard combinatorial problem. In this work, we have applied two unique global methods, Truncated Power Method (TPower) and Low Rank Bilinear Approximation (LowRank), to solve the feature selection problem. These algorithms provide very good approximations to the NP-hard CMI based feature selection problem. We experimentally demonstrate the effectiveness of these procedures across multiple datasets and compare them with existing MI based global and iterative feature selection procedures.

Machine-learned models are often described as "black boxes". In many real-world applications however, models may have to sacrifice predictive power in favour of human-interpretability. When this is the case, feature engineering becomes a crucial task, which requires significant and time-consuming human effort. Whilst some features are inherently static, representing properties that cannot be influenced (e.g., the age of an individual), others capture characteristics that could be adjusted (e.g., the daily amount of carbohydrates taken). Nonetheless, once a model is learned from the data, each prediction it makes on new instances is irreversible - assuming every instance to be a static point located in the chosen feature space. There are many circumstances however where it is important to understand (i) why a model outputs a certain prediction on a given instance, (ii) which adjustable features of that instance should be modified, and finally (iii) how to alter such a prediction when the mutated instance is input back to the model. In this paper, we present a technique that exploits the internals of a tree-based ensemble classifier to offer recommendations for transforming true negative instances into positively predicted ones. We demonstrate the validity of our approach using an online advertising application. First, we design a Random Forest classifier that effectively separates between two types of ads: low (negative) and high (positive) quality ads (instances). Then, we introduce an algorithm that provides recommendations that aim to transform a low quality ad (negative instance) into a high quality one (positive instance). Finally, we evaluate our approach on a subset of the active inventory of a large ad network, Yahoo Gemini.

Class imbalance presents a major hurdle in the application of data mining methods. A common practice to deal with it is to create ensembles of classifiers that learn from resampled balanced data. For example, bagged decision trees combined with random undersampling (RUS) or the synthetic minority oversampling technique (SMOTE). However, most of the resampling methods entail asymmetric changes to the examples of different classes, which in turn can introduce its own biases in the model. Furthermore, those methods require a performance measure to be specified a priori before learning. An alternative is to use a so-called threshold-moving method that a posteriori changes the decision threshold of a model to counteract the imbalance, thus has a potential to adapt to the performance measure of interest. Surprisingly, little attention has been paid to the potential of combining bagging ensemble with threshold-moving. In this paper, we present probability thresholding bagging (PT-bagging), a versatile plug-in method that fills this gap. Contrary to usual rebalancing practice, our method preserves the natural class distribution of the data resulting in well calibrated posterior probabilities. We also extend the proposed method to handle multiclass data. The method is validated on binary and multiclass benchmark data sets. We perform analyses that provide insights into the proposed method.

Recently, Lab41 teamed up with Cyber Reboot (a sister lab) to explore the intersection of deep learning (DL) and cyber security in a software defined network (SDN) environment. We called it Poseidon, based heavily on it being a cool word with the letters s, d, and n in order. The goal was to use predictions about network traffic to automatically update a network's posture. This entailed three main objectives: performing deep learning on packet data, setting up an SDN environment, and scheduling a microservice to connect the two (for more information and code visit our Github page). Since I belong to the cult of deep learning, I was tasked with the first objective.

We consider a priori generalization bounds developed in terms of cross-validation estimates and the stability of learners. In particular, we first derive an exponential Efron-Stein type tail inequality for the concentration of a general function of n independent random variables. Next, under some reasonable notion of stability, we use this exponential tail bound to analyze the concentration of the k-fold crossvalidation (KFCV) estimate around the true risk of a hypothesis generated by a general learning rule. While the accumulated literature has often attributed this concentration to the bias and variance of the estimator, our bound attributes this concentration to the stability of the learning rule and the number of folds k. This insight raises valid concerns related to the practical use of KFCV, and suggests research directions to obtain reliable empirical estimates of the actual risk.

At the very least, a new No.1 contender for each of the top two titles on "SmackDown Live" will be named Sunday night at WWE Money in the Bank 2017 in St. Louis. The pay-per-view could even see three different superstars hold the same belt in the span of just a few minutes, as was the case a year ago. Money in the Bank 2017 is scheduled to start at 8 p.m. EDT, Ordering the event on PPV costs $54.99, but fans can also watch MITB with a live stream on the WWE Network. A subscription to the network costs $9.99 per month, though new subscribers get the first month free. The match card is highlighted by the two main events, which could last for more than half of the PPV.

I'm trying to classify data into two classes and my loss is less than 0.01 under both MSE and BCE. This seems contradictory to me that my performance on the training set is still so low - the ratio of true positives to false positives is at least 1:5 even when sweeping the threshold. Does this behavior mean my net is still not learning?

The availability of large idea repositories (e.g., the U.S. patent database) could significantly accelerate innovation and discovery by providing people with inspiration from solutions to analogous problems. However, finding useful analogies in these large, messy, real-world repositories remains a persistent challenge for either human or automated methods. Previous approaches include costly hand-created databases that have high relational structure (e.g., predicate calculus representations) but are very sparse. Simpler machine-learning/information-retrieval similarity metrics can scale to large, natural-language datasets, but struggle to account for structural similarity, which is central to analogy. In this paper we explore the viability and value of learning simpler structural representations, specifically, "problem schemas", which specify the purpose of a product and the mechanisms by which it achieves that purpose. Our approach combines crowdsourcing and recurrent neural networks to extract purpose and mechanism vector representations from product descriptions. We demonstrate that these learned vectors allow us to find analogies with higher precision and recall than traditional information-retrieval methods. In an ideation experiment, analogies retrieved by our models significantly increased people's likelihood of generating creative ideas compared to analogies retrieved by traditional methods. Our results suggest a promising approach to enabling computational analogy at scale is to learn and leverage weaker structural representations.

Money in the Bank 2017 isn't considered to be among WWE's "Big 4" pay-per-views, though it probably should be. It's leaped ahead of Survivor Series as one of the most important events each year, and it's set for Sunday night in St. Louis. The PPV will feature members of the "SmackDown Live" roster, and there are only five matches scheduled because of the two big co-main events. Below are predictions for the entire Money in the Bank card. The argument can be made for a few wrestlers to win this match.