Recently at home with my mom and sister and I was explaining a bit about the work I’m going to be doing in AI for digital pathology. We got talking about how there is so much data, but a scarcity of good labels, what self-supervised learning is and how it can help overcome this. As I was describing how it works, my sister was like “oh, ya, like this!” and pulled out a coloring book my nieces had been working on. Exactly!
Tag Archives: data science
Germination Project Fellows come to Penn
I was recently fortunate to be invited to speak with an impressive group of high-school students as a part of the Germination Project. They came to Penn to learn about innovation in health care and I spoke with them about how we’re using Data Science to improve patient outcomes.
This week I spoke at DataJawn, an super fun evening of talks and mingling with Philly’s data nerds.
You can have a look through the slides here.
Weapons of Math Destruction – A Data Scientist’s Guide to Disarmament
I’ve had this book on pre-order since spring and it finally arrived on Friday. I subsequently devoured it over the weekend.
The book lays out a clear and compelling case for how data-driven algorithms can become — in contrast to their promise of amoral objectivism — efficient means for reproducing and even exacerbating social inequalities and injustices. From predictive policing and recidivism risk models to targeted marketing for predatory loans and for-profit universities, O’Neil explains how to recognize WMDs by 3 distinct features:
- The model is either hidden, or opaque to the individuals affected by its calculations, restricting any possibility of seeking recourse against – or understanding of – its results or conclusions.
- The model works against the subject’s interest (eg. it is unfair).
- The model scales, giving it the opportunity to negatively affect a very large segment of the population.
The taxonomy provides a simple framework for identifying WMDs in the wild. However, importantly for data scientists and other data practitioners, it forms a checklist (or rather an anti-checklist) to keep in mind when developing models that will be deployed into the real world. As data scientists, many of us are strongly incentivized to achieve feature 3, and doing so only makes it increasingly important to be constantly questioning the degree to which our models could fall victim to features 2 and 1.
Feature 2, as O’Neil lays out, can occur despite the best intentions of a model’s creators. This can (and does!) happen in two ways: First, when a modeler seeks to create an objective system for rating individuals (say, for acceptance to a prestigious university, or for a payday loan), the data used to build the model is already encoded with the socially constructed biases of the conditions under which it was generated. Even when attempting to exclude potentially bias-laden factors such as race or gender, this information seeps into the model nonetheless via correlations to seemingly benign variables such as zip codes or the makeup of a subject’s social connections.
Second, when the outcome of the model results in the reinforcement of the unjust conditions from which it was created, a negative feedback loop is created. Such a negative feedback loop is particularly present and pernicious in the use of recidivism risk models to guide sentencing decisions. An individual may be labeled as high risk due not to qualities of the individual himself, but his circumstances of living in a poor, high crime neighborhood. Being incarcerated based on the results of this model renders him more likely to end up back in that neighborhood, subject to continued poverty and disproportionate policing. Thus the model has set up the conditions to fulfill its own prediction.
As machine learning algorithms become more and more accurate at a variety of tasks, their inner workings become harder and harder to understand. The trend will make it increasingly difficult to avoid feature 1 of the WMD taxonomy. Current advanced techniques like deep learning are creating models that are remarkably performant, yet not fully understood by the researchers creating them, much less the individuals affected by their results. In light of this, we need to think carefully as data scientists about how to communicate these models with as much transparency as possible. How to do so remains an open question. But the internal ‘black box’ nature of these algorithms does not obviate our responsibility to disclose exactly what input data went into a given model, what assumptions were made of that data, and on what criteria the model was trained.
Overall, WMD provides an incredibly important framework for thinking about the consequences of uncritically applying data and algorithms to people’s lives. For those of us, like O’Neil herself, who make our living using mathematics to create data-driven algorithms, taking to heart the lessons contained in Weapons Of Math Destruction will be our best defense against unwittingly creating the bomb ourselves.
That’s like so random! Monte Carlo for Data Science
Another great turnout at the DataPhilly meetup last night. Was great to see all you random data nerds!
Code snippets to generate animated examples here.
Introduction to Machine Learning Talk
There was an amazing turnout at last night’s DataPhilly meetup (~200 people!). I was completely delighted by the turnout and people’s engagement level. Here are the slides of the talk I gave to set up the evening with a high-level introduction to machine learning.
@CjBayesian giving an awesome talk on #machinelearning at tonight’s dataphilly! pic.twitter.com/Hojn5t7tDl
— DataPhilly (@DataPhilly) February 19, 2016
Introducing Penn Signals at DataPhilly
Last week I had the pleasure of giving a talk to a great audience at DataPhilly about the Data Science mission at Penn Medicine. In the talk I introduced the framework we are building to accelerate the development and deployment of predictive applications in health care.
Also on the line-up was (sometimes contributor to bayesianbiologist) Matt Sunquist. He demo’d some of plot.ly‘s most recent features to audible gasps of delight for the audience.
Time-series forecasting: Bike Accidents
About a year ago I posted this video visualization of all the reported accidents involving bicycles in Montreal between 2006 and 2010. In the process I also calculated and plotted the accident rate using a monthly moving average. The results followed a pattern that was for the most part to be expected. The rate shoots up in the spring, and declines to only a handful during the winter months.
It’s now 2013 and unfortunately our data ends in 2010. However, the pattern does seem to be quite regular (that is, exhibits annual periodicity) so I decided to have a go at forecasting the time series for the missing years. I used a seasonal decomposition of time series by LOESS to accomplish this.
You can see the code on github but here are the results. First, I looked at the four components of the decomposition:
Indeed the seasonal component is quite regular and does contain the intriguing dip in the middle of the summer that I mentioned in the first post.
This figure shows just the seasonal deviation from the average rates. The peaks seem to be early July and again in late September. Before doing any seasonal aggregation I thought that the mid-summer dip may correspond with the mid-August construction holiday, however it looks now like it is a broader summer-long reprieve. It could be a population wide vacation effect.
Finally, I used an exponential smoothing model to project the accident rates into the 2011-2013 seasons.
It would be great to get the data from these years to validate the forecast, but for now lets just hope that we’re not pushing up against those upper confidence bounds.
From Whale Calls to Dark Matter: Competitive Data Science with R and Python
Back in June I gave a fun talk at Montreal Python on some of my dabbling in the competitive data science scene. The good people at Savior-fair Linux recorded the talk and have edited it all together into a pretty slick video. If you can spare twenty-minutes or so, have a look.
If you want the slides, head on over to my speakerdeck page.
Montreal R User Group meetup Nov. 14th
After a bit of a summer lull, the Montreal R User Group is meeting up again! We’re trying out a new venue this time. Notman House is the home of the web in Montreal. They hold hackathons and other tech user group meetups, and they are all around great people in an all around great space in downtown Montreal.
Our meetup will feature R super-user Etienne Low-Decarie, who will give a walk through of some of the most powerful packages in R, many of which were built by rstats rock star Hadley Wickham.
I will also kick off the meetup with a short session on how R is revolutionizing data science in academia, journalism, business and beyond.
- November 14th, 7pm at 51 Sherbrooke W.
- BYOL&D (Bring Your Own Laptop & Data)
Don’t forget to RSVP. Hope to see you there!