Interview with a Data Scientist: Mick Cooney

I’m delighted to feature my friend Mick Cooney here as an interviewee. Mick has many years of experience in Finance and more recently in Insurance, he co-ran the Dublin R meetup which was very successful and helped foster a data science community in Dublin. More recently he’s been working over in London at an Actuarial Consultancy – building out a data science practice.

q1. What project have you worked on do you wish you could go back to,
and do better?

I started my career as a quant in a small startup hedge fund. We
developed time series models to forecast short-term volatility in
equities and equity indices as part of an option trading strategy. It
is a fascinating topic and I still dabble in it. Thinking back on the
work done, I would re-engineer large portions of it. I made a ton of
mistakes on both the modelling and implementation side, and the R
language in particular has progressed in strides since I did the bulk
of the work.

For example, the system automatically generates PDF reports of the
forecasts but it does so by hand creating La-TeX files compiled into
PDF. One of the first things I would do is switch all that over to use
either ‘knitr’ or ‘rmarkdown’. I would also use more ‘reproducible
research’ concepts.

That said, I had worked on the modeling for a long time, so I am
content with the basic model. There are many things still to
investigate or implement.

On the modeling side, I worked on a persistency model using survival
analysis, which is how I learned about the subject in the first
place. As a result, there are a lot of different things I would love
to return to and do differently. In retrospect, I was too quick to
move past the simpler models. We could see the assumptions were not
consistent with the data, and so did not fully explore simpler
approaches. I am now curious to learn what insights those simpler
approaches would yield.

Customer churn is such a universal problem I expect I will be working
on it again in the near future. Hopefully I can apply those lessons
then.

***
q2. What advice do you have to younger analytics professionals and in
particular PhD students in the Sciences?

I think the key advice I would give is the same for everyone – never
stop learning. This may be the availability heuristic at play with me,
but I have never seen a connection between qualifications and analyst
quality. All the good analysts I know have curiosity and
initiative. Academic achievements do not come into it at all.

Initiative manifests in many ways. First, when they encounter a
problem they learn what they need to do and get on with it. Second,
much of their knowledge is self-taught. Finally, and I believe most
importantly, they have an inherent curiosity – the best analysts I
know engage in the field in their own time, mainly because they want
to.

This brings up a related issue I have been pondering for some time. I
am ambitious. I want to be a top data scientist some day. I have no
academic ambition whatsoever, but my goal is to be able to hold my own
in any conversation with anyone in the field.

How do I achieve this? What do I need to do to get to that point?

While probably not as keen as the average fan, I love sport – soccer,
the NFL and Gaelic Football in particular. For anyone who has met me
in person, comparing me to a top athlete seems preposterous, but
there is a lot to be learned from top athletes if you want to excel
at your chosen field. Look at how they prepare and train. These
principles almost certainly apply to other professions too, but it is
more fun to talk about sport.

When I read about Lionel Messi, Tom Brady or Colm Cooper (for our
non-Irish readers the recently-retired ‘Gooch’ is arguably the
greatest GAA player to ever play the game – he was majestic to watch),
the one thing that always stands out for me is their fanatical
devotion to their chosen career not their obvious talent. All their
team-mates mention how hard they worked despite their abundance of
natural advantages. Players with huge natural talent often coast, but
elite players are the opposite – they work as hard as the fringe
players slogging to just survive the cut.

In our field, we need to work constantly on improving – going to
Meetups, reading about new techniques, watching videos on YouTube and
looking to strengthen areas where you are weak. This is why a natural
interest and curiosity is so invaluable – it makes these necessary
tasks much less of a burden as they are things you would want to do
anyway.

Secondly, top players do the simple things well, almost never making a
mistake. They are fallible of course, and make mistakes, but almost
never on the basics. They are rigorous about practicing the basic
skills and principles, and that is why they are so good. The bread and
butter of their craft is second-nature to them.

This is why I focus so much on basic statistics classes and reread and
re-watch the books and lectures I find useful. I want these things to
be second nature and they are not.

Probability and statistics are so counter-intuitive that I almost
never get things right on gut feeling. I am almost always wrong. So
much so that I gave a talk about probabilistic graphical models about
a year ago and during the questions at the end made an off-hand joke
about going with the opposite of my intuition.

It was said in jest at the time but is sadly true!

One final piece of advice is to help as many people as you can. Help
people with their homework, with some programming, with their computer
problems and with data problems. You get exposed to all sorts of
topics and problems, most of which you will see again in your
career. You also get the added bonus of people thinking you are
selfless and altruistic, despite being self-serving in reality!

***
q3. What do you wish you knew earlier about being a data scientist?

I have two main things I wish I learned early on in my career, and
both are connected philosophically. First, I wish I had learned about
probabilistic thinking, risk management, economics and statistics –
you can never learn enough about these fundamental topics. Secondly, I
wish I learned it is okay to start working with a bad model that you
know is wrong but simple.

To that first point, I spend a long time fighting my natural desire
for a clean, elegant and correct answer to a problem. I would work on
a problem, get to a point that I was confident pointed us in the right
direction, but then realise that ‘proving’ this was right involved a
huge amount of time and effort, assuming it was possible.

I attributed my natural reluctance to pursue this ‘answer’ as
laziness, and felt guilty. I felt I was being unprofessional and
sloppy. But working on forecasting models for trading taught me that
this was not the case. Models are so imperfect, with so many
compromises it is often more optimal to think about other things first
– what are the limitations of the model in practice, what is it
saying, how are you going to use it. Answer those questions first,
THEN worry about improving it.

This is why I always start with simple, stupid, wrong models. They are
quick to produce, they help you learn a lot about what you are doing,
they fail in spectacular ways and they are sometimes all you need. In
terms of costs and benefits, they are hard to beat.

***
q4. How do you respond when you hear the phrase ‘big data’?

I hate it. It has become a meaningless buzzword used as a means of
making sales.

My attitude to the term is best summarised by the interview you had
with Hadley Wickham: there are three categories of data size,
in-memory, on-disk and finally the truly ‘big data’ problems like
recommender systems. I believe the majority of problems can be solved
by appropriate sampling of your data down to a manageable size and
then analysing those subsets.

After all, the whole point of statistics is to make inferences about a
population from a sample of the data.

Once decided on a solution, putting the model into production and
scaling it for your business is a major issue, but is a problem more
belonging to the realm of network and software engineering. That said,
it is important to keep people with a solid understanding of the
concepts stay involved, just in case some ‘optimisations’ ruin the
output.

***
q5. What is the most exciting thing about your field?

Robert McNamara in ‘The Fog of War’ mentioned that you should never
answer the question asked but instead answer the question you wanted
to be asked, so with your forebearance I will first answer a liberal
interpretation of that question: what work gets me excited?

The short answer to that question is all sorts of things do, but they
are often small things related to work I am doing. In the last few
months, I was excited to try out dataexpks (a data exploration package
I am co-creating) on a brand new data set to see what it showed me and
how well my code worked. I love think of ways to use Monte Carlo
simulation to test the output of various regression models, and over
Christmas I was fascinated by a short project trying out methods of
investigating differences between a subpopulation within a larger
population.

I am fascinated by new ways to learn the fundamentals – there are a
few excellent ones out there and I read them all the time. I can never
learn enough as in my experience reality tends to present us with
basic statistical problems in new and unusual ways.

Having multiple perspectives and multiple approaches is invaluable in
those situations.

Regarding your original question as I think you intended, I think the
advances in reinforcement learning techniques probably have the
biggest potential – some of the Atari gameplaying from Deep Mind was
eye-opening. Sadly, if history is any guide, much of it will prove to
be hype, but I imagine some very interesting results to come from the
work.

***
q6. How do you go about framing a data problem – in particular, how do
you avoid spending too long, how do you manage expectations etc. How
do you know what is good enough?

Framing a data problem is a tough one to answer – I am not sure what I
do or how to articulate it. I have had the good fortune to help a lot
of people with their projects and problems, exposing me to a wide
variety of problems. I learned something from all of them and I rely
on that a lot.

I also read a lot of blogs, articles and subscribe to mailing
lists. While rarely having the time to read all this, often all you
need to get started on a problem is a vague memory of some technical
topic that may help and some terminology to Google.

As a result, the first thing I focus on is understanding the problem:
what is being asked? Do we have any data? What does is it look like?
Are there other data available we can use to enrich or use as a
substitute?

Going through that process will suggest approaches to use, and at that
point I draw upon previous experience, however tangential to the
problem..

By keeping this focus, your other questions are straightforward to
answer: if the current model is not likely to improve the answer by an
amount relevant to the goal, it is not worth spending more time
on. Similarly, knowing what is needed will tell you if your current
model is good enough, or often if there is a model that is good enough
– it is possible the level of accuracy required is not feasible.

In the latter case, discovering that early is much better than later –
you know not to waste time, money and resources on a lost cause.

***
q7. You’ve spoken before about the ‘need for apprenticeships’ in Data
Science. Do you have any suggestions on what that would involve? Are
meetups and coaching a good first start?

To explain the point I was making on that note, I think there is a lot
of implicit knowledge in this field, and I have been told a number of
times from people looking for help that people feel overwhelmed by the
sheer amount of knowledge people feel they need to know.

I do not think this is true, but I understand its origin: there is so
many different aspects to working with data it is tough to know where
to start. I always start very simple, but as I mentioned early, it
took a lot of time, thought and effort to get to that point, and it is
not easy to explain these ideas in theory – you have to work on a
number of different datasets to get a feel for how to do this.

As a result, I believe an approach such as mentoring or
apprenticeships are an effective approach to teach people – more
experienced analysts can guide junior members around the various
pitfalls and traps that are easy to fall into. It allows us to
illustrate that fancy and sophisticated techniques and algorithms are
not needed to do interesting work – some of the most interesting work
I have seen involved little more than summary statistics along with
basic models like linear regression and decision trees.

This is hard to learn from a book – almost impossible. The closest
book I read that talks about this is “Data Analysis Using Regression
and Multilevel/Hierarchical Models” by Gelman and Hill, stressing the
importance of starting from simple models. I would love to know if
there are more.

That said, I could only appreciate the point because I was already
experienced, a younger version of myself would have missed the
point. It would not have occurred to me that the right way to do
something is to do the simple and obvious thing.

I am a firm believer in the KISS principle. Keep It Simple, Stupid.