Stats and stuff

Demetrios Papakostas*

Got a PhD in statistics from Arizona State University


*not to be confused with the painter from Montreal

Overview

Statistical modeling I have a PhD in statistics, with a focus on Bayesian statistics and causal inference. I stay up to date with research methodology in the applied statistical world, and find Bayesian additive regression trees (BART) to be particularly useful in these kinds of problems. On the implementation side, I am very fond of the stochtree software suite. My personal work see: Forecasts... forecause?. Coming soon is some stuff on Bayesian optimization, "machine aided" physics, and election forecasting.

BART

Data science On a more day to day side, I am interested in data science and analytics. I have experience in sports, bio-informatic, social, and health data. In my last 8+ years as a data scientist, I have studied datasets with very few observations and some with gigabytes of data. Know R and Python very well and 3 years of experience with SQL. My professional aims are to try and incorporate more causal analyses into common data studies and to be really careful about offering advice that could fall victim to selection effects and biases.

Links

Latest

Visualization Visualization of data is my favorite part of the job, lowkey. While this is a subset of data science, I really enjoy making cool graphs. My goal is to better learn d3.js, but to date mostly use R (with shiny and reactable), python, excalidraw, and drag and drop softwares, like datawrapper and flourish. I use Quarto, keynote, and react.js for reports and presentations. Pictured is a hypothetical job search template (with fake data).

Application tracker

About

I am a statistician/data scientist. Prior to that, I obtained a physics degree from Villanova University, which I attended from 2014-2018. That led to a PhD in statistics from Arizona State University followed by a stint as a baseball researcher with the Houston Astros. Here you will find a link to a recent publication on the causal effect of forecasting bankruptcy on bankruptcy. This is a cool quarto version of the same thing.

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Took this pic in 2017
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September 2021
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Me Circa 2018
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My PhD tree. Direct descendant of Euler.
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Meteora, Greece
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Took this pic in 2017
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Why BART is the best.
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Chicken coop

Born Connecticut (1996)
12 yr New Hampshire (2014)
4 Years Suburban Philadelphia (2018)
2023 Tempe Arizona
0.25 yr Houston, Texas
1.5 yr Santa Fe, New Mexico
0.5 yr Albuquerque

Research

Summary

Currently, I am conducting statistical research. Were I not in statistics, I could see some myself pursuing a career in economics, meteorology, or sports statistics. If I had more artistic ability and/or, careers in film-making, weather forecasting, and architecture might be cool.

CV

The CV basically says everything in this section. Here is a link. CV. Ideally, this CV will expand to something respectable in the future as more skills are developed and more evidence of some competence is demonstrated.

Presentations

List of presentations can be found here . I have presented posters at mutliple physics conferences, a social science symposium, and have given research talks at Arizona State University and Villanova University since beginning graduate school.

Publications

My past research in physics resulted in two publications. Further detail can be found here , or here in this google scholar link

Statistics

In grad school, I have had the great fortune to be working with Dr Richard Hahn on causal inference and Bayesian methods. Research interests including synthetic control methods, non-parametric regression, and more recently Bayesian methods. Work mainly in R, but have occasionally used python or C++.

Physics

For 2 years, I worked with Dr. Jeremy P Carlo at Villanova University conducting research in condensed matter physics. Primarily, we synthesized and analyzed double perovskites, materials of great interest, in the solar industry. Additionally, conducted experiments at TRIUMF, Canada's premier physics research facility.

Page Break

Not an endorsement of IKEA, the colors just matched.


Research projects

Here is a link to a few interesting things (in my opinion) that I have done.

  • Have been documenting past research projects into quarto blogs. This is a work in progress, but here is a completed one that allows users to reproduce the "Do Forecasts of Bankruptcy Cause Bankruptcy" paper. Forecasts... forecause?


  • This is a link to an exploration of deep neural networks for causal inference. This was a class project with Drew Herren, who did a lot of the heavy lifting here. Useful project to learn PyTorch and also emphasizes the advantages of using trees over neural networks for causal inference. Click here.


  • Developed many Rshiny apps that are completely interactive. Give them a look here: Link to shiny app repositories


  • Data visualizations

  • Interactive display of how Bayesian Additive Regression Trees operate. I think this helps build intuition into their secret sauce and why they work so well in practice.
  • Data scraped by former colleague at Arizona State University Jerome Goh. Describes gas prices per state over time.

  • Plot of my steps in March 2025. Part of an ultimately triumphant step challenge.
  • Visual of restaurant ratings in different cities I've lived in or visited long enough to eat at enough places to judge. Ratings mostly cluster around 3.5 stars, which makes sense given that restaurants have to be decent to stay open. Interesting selection effect as places I spent more time in showcase more time to find less desirable options. The plot beneath is a map that shows distributions of ratings by metros.


  • Visual of the windchill calculator.



  • Fun Stuff (probably will be teaching section eventually)

    Legally obligated to share my interests.

    Bio

    I grew up in a Greek family in New England, and Greek was technically my first language. Cumulatively, I have spent over half a year of my life in is Avgerinos, a small, but beautiful village in Greece where my father grew up. I very much enjoyed growing up in the northeast, despite the bad weather.

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    Interests

    I am an avid fan of the weather, particuarly winter storms and hurricanes. In my free time I like to bool with friends, walk, ride my bike, go to the lanes, frequent disc, watch stuff, and play with data. Miniature mechanical keyboards are cool too, as is woodworking.

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    The restaurant industry

    Through former jobs and family occupation, I have become well acquainted with the restaurant industry. A good recommendation is the Breakfast Club in Manchester New Hampshire, currently a top rated breakfast/lunch hotspot in the state of New Hampshire.

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    US states that I have "visited": 16/50 +D.C. & 3 provinces in Canada.(May 25,2019) --> 21/50 Nov 2025
    Create your own visited states map or check out the JavaScript Charts.

    Contact

    Im pretty bad at starting and ending conversations, but luckily I'm mediocre in between.

    TEMPE, AZ Current

    TBD
    State

    d.v.papakostas@gmail.com

    Office Hours: TBD

    +1 603-***-****