John Muller, Developer in Charlotte, NC, United States
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John Muller

Verified Expert  in Engineering

Analyst and Developer

Charlotte, NC, United States
Toptal Member Since
September 4, 2020

John is a computer scientist, data scientist, finance quant, and creative problem solver. He loves the challenge of taking on real-world problems with algorithms, data structures, and professionally written code. John has a Ph.D. in computer science and over ten years of experience using R and Python and for modeling and visualization, and data manipulation. John is an effective communicator with both technical and business-oriented colleagues.


Python, SQL, Analytics, Data Science, Machine Learning, Algorithms...
Python, Google BigQuery, Docker, Graph Machine Learning, Machine Learning
Large Consumer Bank
Apache Hive, Hadoop, PySpark, R, SQL, Python




Preferred Environment

Linux, RStudio, PyCharm, Windows

The most amazing...

...project I've worked involved analyzing survey data from data scientists. We clustered the observations and were fascinated to see the natural groupings emerge.

Work Experience

Data Scientist

2023 - PRESENT
  • Classified customer feedback and automatically generated customer responses (NLP projects).
  • Wrote code to optimize the cutoff threshold percentage for the classification service.
  • Improved the classification service with clever model enhancements.
Technologies: SQL, Python, Analytics, Data Science, Machine Learning, Algorithms, Artificial Intelligence (AI)

Data Scientist

2021 - PRESENT
  • Applied Graph ML methods to create embeddings to be used for product recommendations.
  • Wrote SQL queries to create rule-based recommendations.
  • Applied hyperparameter optimization to improve ML algorithms.
Technologies: Python, Google BigQuery, Docker, Graph Machine Learning, Machine Learning

Senior Analyst, Code Review Team

2019 - PRESENT
Large Consumer Bank
  • Reviewed code (mostly Python and SQL) to determine if it accurately and completely met all documented requirements.
  • Performed tests on the data and code to check for missing or unexpected values.
  • Reran the original code and compared the output to the original output.
  • Worked on projects that required a high level of skill in Python and SQL and occasionally R and even SAS; and often times requiring skill in and knowledge of Spark, Hadoop, and Hive.
Technologies: Apache Hive, Hadoop, PySpark, R, SQL, Python

VP, Portfolio Construction Group and Model Implementation Group

2013 - 2018
Acadian Asset Management
  • Designed and built a dashboard for PMs to analyze portfolio exposures within and across strategies.
  • Developed code to add transaction costs to our attribution and a web app (Bokeh) for exploring the results.
  • Built an automatic testing program to run simple pass/fail tests on code where no explicit test code exists. Used Python’s introspection to find methods and method signatures to assign valid values for arguments.
  • Worked on other projects including an investment strategy capacity analysis, rebalancing a schedule frequency analysis, a ranking of broker performance, an FX hedge reporting module, an access layer to alpha model data, and more.
Technologies: SQL, StatsModels, NumPy, Pandas, Python

Lead Data Scientist

2012 - 2013
  • Estimated the value of a marketing campaign vis-à-vis resulting sales using a time series analysis,.
  • Analyzed customer retention using survival analysis to find differences across markets.
  • Predicted government employment releases using lasso regression and random forests.
Technologies: SQL, Python, R

VP, Head of Analytics and Visualization

2007 - 2012
State Street Associates
  • Led a collaboration between research and the securities lending business to build analytic tools to support trading.
  • Worked on analysis and modeling projects including predicting hard-to-borrow securities and analyzing the relationship between real and synthetic shorts using options.
  • Led a team for new holdings indicators, i.e., a trading signal for equity and fixed income.
  • Managed teams that developed and released 14 new foreign exchange and equity flow indicators.
Technologies: Spotfire, SQL, MATLAB, Python

Senior Vice President

2001 - 2007
Bank of America
  • Coded (using R) and back tested various improvements to the existing momentum-style strategy drawing data from MarketQA, IDC, IBES, and Compustat.
  • Provided quantitative support for users of Barra’s Enterprise Performance product for return attribution.
  • Designed and coded fixed income tools using R and C++.
  • Developed code to calculate generic yield curves and bond asset swap spreads.
  • Conducted an extensive analysis of the customer database and provided analytic research on the effects of pricing policies to support the mortgage pricing team.
Technologies: C++, R, SQL

Exploratory Data Analysis of Survey Data

I worked with a company called Talent Analytics to cluster some survey data they had collected on data scientists. The survey asked how they spent their time, e.g., coding, model building, and presenting.

It was fascinating to see the natural groupings emerge from the data. For example, there was a group that did mostly data manipulation and extraction, a modeling group, a visualization group that seemed to mostly interact with the business side.

Data Science/Machine Learning Projects
A collection of recent data science/machine learning projects to demonstrate my range of knowledge and ability in developing projects using Python and related libraries.
Please have a look. I am adding new projects frequently.
1982 - 1988

Ph.D. in Information and Computer Science

Georgia Institute of Technology - Atlanta, GA, United States


Certificate in Quantitative Finance

Carnegie Mellon


Pandas, PySpark, NumPy


PyCharm, StatsModels, MATLAB, Spotfire


Python, R, SQL, C++, Java, Python 3


Spark, Hadoop


Data Science


Apache Hive


Windows, RStudio, Linux, Docker


Graph Theory, Algorithms, Quantitative Finance, Analytics, Data Visualization, Data Analytics, Regression, Regression Modeling, Data Analysis, Statistical Modeling, Data Structures, Calculus, Numerical Methods, Derivatives, Google BigQuery, Graph Machine Learning, Machine Learning, Artificial Intelligence (AI)

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