This weekend I took part in The Pitt Challenge Hackathon hosted by the School of Pharmacy and the Clinical and Translational Science Institute. I found this hackathon interesting because it had specific goals and challenged the participants to “Change the way the world looks at Health.” I went to the event with absolutely no prior ideas about what to build. I enjoy participating in hackathons for a chance to work with a completely new group of team members every time. I joined a team of two software professionals Zee and Greg right after registration. We were then joined by a business major – Shoueb during the official team formation stage of the event. The hackathon organizers provided us with ample opportunities to have discussions with researchers, professors and practitioners about the problems they’d like to solve with technology.
We started with a lot of interesting ideas and everyone in the team had a lot to contribute. We realized that almost all of our ideas revolved around the concept of increasing the interaction between the patient and providers outside of the health care setting. Currently, the patients have little interaction with the health care providers apart from the short face-to-face meetings and sporadic phone calls. Providers are interested in knowing more about their patients during their normal activities. Patients would also feel better cared for when the providers are more vested in them. We began with a grand scheme of creating a three-way communication channel with patient, physicians and pharmacists. After having more discussions with the mentors, we soon understood our big challenges – ‘busy schedules’ and ‘incumbent systems.’ We decided to focus on patient-pharmacy interactions. We brainstormed ideas about how we can build a system that ties well with the existing systems and isn’t too demanding in terms of time, either from the pharmacists or the patients. We decided to call ourselves – “Pharma-C” and after appropriate amount of giggling over the name, we sat down to think about the tech.
We wanted to design a system that could be less intrusive than phone calls, where both participants must be available at the same time, but also more visible than emails that could be left ignored in the promotions inbox. We began with an idea of using an email based system that could also appear as Google Now Cards as notifications on phones and smart devices. To our disappointment, we learned that Google Now only supports schemas for a limited number of activities (such as restaurant reservations, flights etc.). As a result, we moved on to a custom notification service. We agreed upon using the Pushover app which made it very easy to build a prototype for the hackathon.
We built a web-based system that could be connected to the existing loyalty programs from the pharmacies. The patients could opt for signing up for additional follow-up questions about their prescriptions. These questions could be generic ones such as: How many prescribed doses have you missed this week?, Is your prescribed medicine affordable?, Do you have questions about your current prescription?; or specific follow-up questions about the drugs they are taking. One could be interested in knowing how the patients are doing, whether the drug is having the desired effects or even reminding them about the common side-effects. Once signed up, a weekly script could send notifications to the participants and collect their responses from their preferred devices. Having such a system in place would help the pharmacists gather better information about the patients and offer interventions. They could look at the summary information screen when they make their follow-up calls according the existing systems in place. We believe the such a system could benefit both the pharmacies and the users without disrupting their regular workflows.
During the course of 24 hours, we finished building a working prototype and could demo everything in real-time to all our judges. One addition that improve the challenge would be to release some datasets for the participants to work with. We wanted to try some interesting data analysis methods for our problems but were limited to work on data collection hacks. Overall, I enjoyed taking part in the Pitt Challenge Hackathon and will look forward to their future events.
When talking about machine learning, you may encounter many terminologies such as such as “online learning,” “active learning,” and “human in the loop” methods. Here are some of my thoughts on the relationship between interactive machine learning and machine learning in general. This is an extract from my answers to my comprehensive exam.
Traditionally machine-learning has been classified into supervised and unsupervised learning families. In supervised learning the training data, , consists of N sets of feature vectors each with a desired label provided by a teacher:
where, is a d-dimensional feature vector
and is the known label for it
The task is to learn a function, , which can be used on unseen data.
In unsupervised learning, our data consists of vectors , but no target label . Common tasks under this category include clustering, density estimation and discovering patterns. A combination of these two is called semi-supervised learning, which has a mixture of labeled and unlabeled data in the training set. The algorithm assigns labels for missing data points using certain similarity measures.
While researchers are actively looking at improving the unsupervised learning techniques, supervised machine learning has been the dominant form of learning till date. However, traditional supervised algorithms assume that we have training data along with the labels readily available. They are not concerned with the process of obtaining the target values s for the training dataset. Often, obtaining labelled data is one of the main bottlenecks in applying these techniques in domain specific applications. Further, current approaches do not provide easy mechanisms for the end-users to correct problems when models deviate from the desired learning concept. NLP models are often built by experts in linguistics and/or machine learning, with limited or no scope for the end-users to provide input. Here the domain experts, or the end-users, provide input to models as annotations for a large batch of training data. This approach can be expensive, inefficient and even infeasible in many situations. This includes many problems in the clinical domain such as building models for analyzing EMR data.
“Human-in-the-loop” algorithms may be able to leverage the capabilities of a domain expert during the learning process. These algorithms can optimize their learning behavior through interaction with humans. Interactive Machine Learning (IML) is a subset of this class of algorithms. It is defined as the process of building machine learning models iteratively through end-user input. It allows the users to review model outputs and make corrections by giving feedback for building revised models. The users are then able to see model changes and verify them. This feedback loop allows end-users to refine the models further with every iteration. Some early examples for this definition include applications in image segmentation, interactive document clustering, document retrieval, bug triaging and even music composition. You can read more about this in the article titled "Power to the People: The Role of Humans in Interactive Machine Learning" (Amershi et.al., 2014).
Interactive machine learning builds on a variety of styles of learning algorithms:
Reinforcement Learning: In this class of learning we still want to learn but we see samples of but no target output . Instead of , we get a feedback from a critic about the goodness of the predicted output. The goal of the learner is to optimize for the reward function by selecting outputs that get best scores from the critics. The critic can be a human or any other agent. There need not be a human-in-the-loop for the algorithm to be classified under reinforcement learning. Several recent examples of this type include building systems that learn to play games such as Flappy Bird, Mario etc.
Active Learning: Active learning algorithms try to optimize for the number of training examples. Such an algorithm would ask an oracle to give labels such that it can achieve higher accuracy with smallest number of queries. These queries contain a batch of examples to be labelled. For example, in SVMs, one could select training sets for labeling that are closest to the margin hyperplanes to reduce the number of queries.
Online Algorithms: Online learning algorithms are used when training data is available in sequential order, say due to the nature of the problem or memory constraints, as opposed to a batch learning technique where all the training data is available at once. The algorithm must adapt to the continuous stream of data made available to it. Formulating the learning problem to handle this situation forms the core of designing algorithms under this class. A commonly used example would be the online gradient descent method for linear regression: Suppose we are trying to learn the parameters for . We update the weights when we receive the th training example by taking the gradient of the defined error function: . Where, is defined as the learning rate.
Interactive machine learning methods can include all or some of these learning techniques. The common property between all the interactive machine learning methods is the tight interaction loop between the human and the learning algorithm. Most of the effort in interactive machine learning has been about designing interactions for each step of this loop. My work on interactive clinical and legal text analysis also follows this pattern. You are welcome to check out those posts as well!
I have been attending a reading group on visualization tools for the last few weeks. This is a unique multi-institution group that meets over web-conferencing at 4 PM EST / 1 PM PST on Fridays. It includes a diverse bunch of participants including non-academic researchers.
Every week we vote on and discuss a range of topics related to building tools for visualizing data.
This week, it was my turn to lead a discussion on the Lumiere paper. This is the research responsible for the now retired Clippy Office assistant. I also noticed a strong ISP presence in the references section as the paper focuses on Bayesian user modeling.
During the discussion, we talked about how we can offer help to use vis tools better. Here are my slides from it:
Eric Horvitz, Jack Breese, David Heckerman, David Hovel, and Koos Rommelse. 1998. The lumière project: Bayesian user modeling for inferring the goals and needs of software users. In Proceedings of the Fourteenth conference on Uncertainty in artificial intelligence (UAI’98), Gregory F. Cooper and Serafín Moral (Eds.). Morgan Kaufmann Publishers Inc., San Francisco, CA, USA, 256-265.
Justin Matejka, Wei Li, Tovi Grossman, and George Fitzmaurice. 2009. CommunityCommands: command recommendations for software applications. In Proceedings of the 22nd annual ACM symposium on User interface software and technology. ACM, New York, NY, USA, 193-202.
I participated in the PennApps hackathon in Philadelphia this weekend. While most of the city was struck with a bad snow storm, a group of hackers holed up inside the Penn engineering buildings to work on some cool hacks. My team consisting of three other hackers: Daniel, Alex and Madhur, decided to work on an app that could predict blood glucose levels of diabetes patients by building machine learning models.
We used the OneTouch Reveal API to gather some data provided by the Johnson & Johnson’s company. They are the manufacturers of OneTouch glucose monitors for diabetes patients. They also give their patients an app for tagging events like exercise (light, moderate, heavy etc.), when they eat food and use insulin (different kinds – fast acting, before/after meals etc.). Our team thought that it might be a good idea to hack on this dataset to find out whether we could predict patients’ glucose levels without them having them to punch a hole in their fingers. A real world use case for this app would be to alert a patient when we predicted unusual glucose levels or have them do an actual blood test when the confidence on our predictions falls low.
We observed mixed results for the patients in our dataset. We did reasonably well for those with more data, but others had very few data points to make good predictions. We also saw that our predictions became more precise as we considered more data. Another issue was that the OneTouch API did not give sufficient information about food and exercise events for any of the patients – mostly without additional event tagging. As a result, our models were not influenced much by them.
We believe that in the near future, it would be common for the patients to have such monitors communicate with other wearable sensors such as smart watches. Such systems would be able to provide ample information about one’s physical activity etc., to make more meaningful predictions possible. Here’s a video demonstrating our proof-of-concept:
Update: We received the best student paper award for our paper at JURIX’15!
In an earlier post, I talked about my work on Natural Language Processing in the clinical domain. The main idea behind the project is to enable domain experts to build machine learning models for analyzing text. We do this by designing usable tools for NLP without really having the need to send datasets to machine learning experts or understanding the inner working details of the algorithms. The post also features a demo video of the prototype tool that we have built.
I was presenting this work at my program’s bi-weekly meetings where Jaromir, a fellow ISP graduate student, pointed out that such an approach could be useful for his work as well. Jaromir also holds a degree in Law and works on building AI systems for legal applications. As a result, we ended up collaborating on a project on using the approach for statutory analysis. While, the main topic of discussion in the project is on the framework in which a human experts cooperate with a machine learning text classification algorithm, we also ended up augmenting our approach with a new way of capturing and re-using knowledge. In our tool datasets and models are treated separately and our not tied together. So, if you were building a classification model for say statutes from the state of Alaska, when you need to analyze laws from Kansas you need not start from scratch. This allows us to be in a better starting place in terms of all the performance measures and build a model using fewer training examples.
Jaromír Šavelka, Gaurav Trivedi, and Kevin Ashley. 2015. Applying an Interactive Machine Learning Approach to Statutory Analysis. In Proceedings of the 28th International Conference on Legal Knowledge and Information Systems (JURIX ’15). Braga, Portugal. [PDF] – Awarded the Best Student Paper (Top 0.01%).
Update: Here’s our full paper announcement with source-code release…
I am working on a project to support the use of Natural Language Processing in the clinical domain. Modern NLP systems often make use of machine learning techniques. However, physicians and other clinicians, who are interested in analyzing clinical records, may be unfamiliar with these methods. Our project aims to enable such domain experts make use of Natural Language Processing using a point-and-click interface . It combines novel text-visualizations to help its users make sense of NLP results, revise models and understand changes between revisions. It allows them to make any necessary corrections to computed results, thus forming a feedback loop and helping improve the accuracy of the models.
Here’s the walk-through video of the prototype tool that we have built:
At this point we are redesigning some portions of our tool based on feedback from a formative user study with physicians and clinical researchers. Our next step would be to conduct an empirical evaluation of the tool to test our hypotheses about its design goals.
Gaurav Trivedi. 2015. Clinical Text Analysis Using Interactive Natural Language Processing. In Proceedings of the 20th International Conference on Intelligent User Interfaces Companion (IUI Companion ’15). ACM, New York, NY, USA, 113-116. DOI 10.1145/2732158.2732162 [Presentation] [PDF]
Gaurav Trivedi, Phuong Pham, Wendy Chapman, Rebecca Hwa, Janyce Wiebe, Harry Hochheiser. 2015. An Interactive Tool for Natural Language Processing on Clinical Text. Presented at 4th Workshop on Visual Text Analytics (IUI TextVis 2015), Atlanta. http://vialab.science.uoit.ca/textvis2015/ [PDF]
Gaurav Trivedi, Phuong Pham, Wendy Chapman, Rebecca Hwa, Janyce Wiebe, and Harry Hochheiser. 2015. Bridging the Natural Language Processing Gap: An Interactive Clinical Text Review Tool. Poster presented at the 2015 AMIA Summit on Clinical Research Informatics (CRI 2015). San Francisco. March 2015. [Poster][Abstract]