Reddit Data Scientist Interview Guide

Interview Guide

Aug 02

The role of a Reddit Data Scientist

Considering Data Scientist Role at Reddit?

As a data scientist at Reddit, you'll be part of a team that is responsible for analyzing data to uncover insights and drive decision-making across the organization. Your work will help shape the product roadmap and strategy, and ultimately impact the experiences of millions of users.

Data scientists at Reddit work across various domains, including user engagement, product analytics, business analytics, and data infrastructure. They analyze data to understand user behavior, product performance, and business metrics, and use statistical and machine learning techniques to identify patterns and trends. Reddit offers a range of data science roles, from Data Scientist to Senior Data Scientist, Data Analyst, and Machine Learning Engineer. 

For example, they were recently looking for a Staff Data Scientist to be a part of the Ads Data Science team. In this role, you will work closely with product managers, engineers, and data scientists to up-level the experimentation capabilities of the ads organization. They were also looking for a Staff Data Scientist to join our Safety Insights team, and lead strategic and product analytics for safety signals, actioning and measurement.  In this role, you will partner with the Safety Core product and engineering team, as well as Safety Enforcement teams (data science, threat analysis and operations) and User Research.

It's worth noting that the names of the positions and their responsibilities may vary depending on the region and the specific team.

How to Apply for a Data Scientist Job at Reddit?

To apply for a Data Scientist job at Reddit, go to Reddit's career website and search for data scientist roles. You can also check other job search websites, such as LinkedIn or Glassdoor, to see if there are any open positions.Carefully read through the job description and requirements to make sure you meet the qualifications and that the role aligns with your interests and experience. Once you have found a position that you are interested in, you will be able to submit an application online. However, we would highly recommend taking the referral route if you know someone in the company as it increases your chances meaningfully. A tip we had regarding your resume - make a few tweaks for the position and the role you are applying for which will help you have a better chance compared to other candidates. If you're not sure how to do that, Prepfully offers a resume review service, where actual Reddit recruiters will give you feedback on your resume.

Reddit Data Scientist Interview Guide

As a part of the Reddit Data Scientist interview, you will need to go through multiple interview rounds:

1.  Recruiter round - The first round is to have a quick discussion about your work experiences and the roles you’ve had in the past company. The standard phone screen is typically taken by a Recruiter from HR.

2. Technical Screening - The second round is an important step in the hiring process. Candidates will meet with a Senior Data Scientist for a technical screen, which will cover a range of topics related to data science and machine learning. 

3. Onsite Interview - The onsite round will consist of five sessions. You can expect to meet with engineers, Data Scientists, Product Managers, hiring managers and a senior Machine Learning Engineer. 

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Reddit Data Scientist: Recruiter Round

Overview

During this round, the focus is typically on assessing if your abilities align with the position being applied for. This may include informal queries about your experiences and qualifications. The goal of this session is to provide the HR team with a deeper understanding of your background and to assist you in understanding the role. When prompted with the question, "Tell me about yourself," we’d recommend highlighting key points or strengths that can leave a positive impression on the interviewer and increase the chances of advancing to the next round.

Interview Questions

  • Why do you want to join Reddit?
  • Why do you think you will be a good fit for the role?
  • What responsibilities do you expect to have from your job at Reddit?
  • Tell us more about your management experience.
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Reddit Data Scientist: Technical Screening

Overview

In this round, you will be meeting with a Senior Data Scientist for a technical screen. The technical screen will include a couple of small Python coding questions to assess your proficiency in the language, as well as questions on basic ML knowledge and online experimentation. Machine learning topics on which you can expect questions include - regression, regularization, dimensionality reduction, performance metrics, boosting and neural networks. Additionally, if the role is NLP-specific, candidates can expect questions on transformers. Some candidates also reported being asked custom SQL questions based on a Reddit schema. You should be prepared to demonstrate your proficiency in SQL and your ability to work with large datasets. 

Interview Questions

  • How would you implement a regularized regression model in Python?
  • What is dimensionality reduction and why is it useful? Give an example of a technique used for dimensionality reduction?
  • How would you evaluate the performance of a machine learning model?
  • Explain the concept of boosting and give an example of when you would use it?
  • Explain how neural networks work and give an example of a use case?
  • Explain how transformers work and give an example of when you would use them?
  • Walk me through a SQL query you wrote to extract information from a large dataset?
  • How would you handle missing values in a dataset when performing a machine learning analysis?
  • How would you approach optimizing a model's hyperparameters?
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Reddit Data Scientist: Onsite Interview

Overview

The onsite round will consist of five sessions. You can expect to meet with engineers, Data Scientists, Product Managers, hiring managers and a senior Machine Learning Engineer. These interviews will heavily focus on case studies, with an emphasis on product sense case studies. You should be prepared to demonstrate your ability to think critically about how your work impacts the end product and how it fits into Reddit's overall business strategy.

In addition to case studies, you will also have multiple coding sessions. You should be prepared to answer Python questions and algorithmic leetcode questions. This will give the interviewers a chance to assess your coding ability, problem solving skills and familiarity with data structures and algorithms.

Interview Questions

  • Tell us about a time when you had to make a trade-off between model accuracy and business impact. How did you approach this trade-off?
  • Reddit is looking to increase user engagement. Walk us through how you would approach this problem as a Data Scientist.
  • Describe a time when you had to explain complex statistical concepts to a non-technical stakeholder. How did you approach this conversation?
  • Tell us about a product you love and why you love it. How would you improve it?
  • Reddit has a feature for recommending subreddits to users. What metrics would you use to measure the effectiveness of this feature?
  • How would you measure the impact of a new ad format on user engagement?
  • Write a function in Python to determine if a given string is a palindrome.
  • Implement a binary search algorithm in Python.
  • Given a list of integers, write a Python function to find the two numbers that add up to a given target.

Tips to ace the Reddit DS Interview

When you are preparing for a Reddit Data Science interview - we’d recommend the following things to keep in mind:

  • Learn as much as you can about Reddit, including its mission, values, and products. Look for recent news or events related to the company that may be relevant to the role you are applying for. Check out Reddit's values page for more information.
  • Refresh your knowledge of fundamental machine learning concepts, such as regression, regularization, model selection, evaluation, and optimization.
  • Review data structures, algorithms, and python programming.
  • Review your previous experiences and be prepared to discuss how you approached various problems or situations. Focus on examples that highlight your teamwork, communication skills, and ability to work in a dynamic environment.
  • Explain your thought process and how you approach problem-solving. Focus on how you break down complex problems into manageable steps, analyze the data, and arrive at solutions.

Responsibilities of a Data Scientist at Reddit

The responsibilities of a data scientist at Reddit across roles can broadly be seen as-

  • Explore new experiment designs/techniques such as budget split experiments, switchback testing, small sample enhancements, Bayesian approaches, causal inference methodologies, dosage response studies, staggered experiments etc and apply them successfully for complex experiments.
  • Liaise with the centralized experimentation team in building platform features to accelerate ads experimentation.
  • Track and own the experiment calendar for the ads org. Run weekly experiment review discussions.
  • Create frameworks for making metric trade-off decisions, especially when they span multiple organizations (e.g. ads vs consumer metric tradeoffs).
  • Identify actionable and impactful insights through metrics and analyses, in order to improve Reddit’s safety systems and outcomes.

Skills and Qualifications needed for Data Scientists at Reddit

Some of the skills and qualifications that may be required for a Data Scientist at Reddit include:

  • Build experience in quantitative/modeling roles to help you develop a strong foundation in data analysis and modeling.
  • Become proficient with statistical analysis and programming languages such as Python and SQL. These skills are essential for working with large datasets and conducting complex analyses.
  • Develop an understanding of experimentation and causal inference techniques. Experimentation is a core part of the data science workflow at Reddit, and it's important to be familiar with the latest techniques and methodologies.
  • Be proficient with relational databases (SQL), programming languages (Python or R), statistics, experimentation, and causal inference analyses. These skills will help you work effectively with data and communicate your findings to others.
  • Experience with experimentation, preferably for a consumer-facing service/app is important. This will help you understand how to design experiments that are relevant to users and how to analyze the data to generate meaningful insights.

Salary Ranges

The salary range for a Reddit data scientist can be quite competitive. Entry-level data scientists at Reddit can expect a salary in the range of $100,000 to $130,000 per year. Mid-level data scientists with a few years of experience can expect a salary in the range of $130,000 to $170,000 per year. Senior data scientists or those with significant experience or leadership roles can expect salaries well over $200,000 per year, potentially reaching up to $250,000 or more, including bonuses and stock options.

Conclusion

The interview process for a Data Scientist role at Reddit typically includes 3 primary rounds - the recruiter round, a technical phone screen and the final onsite interview round. The first round is to have a quick discussion about your work experiences and the roles you’ve had in the past company. The standard phone screen is typically taken by a Recruiter from HR. The second round is an important step in the hiring process. Candidates will meet with a Senior Data Scientist for a technical screen, which will cover a range of topics related to data science and machine learning. The onsite round will consist of five sessions. You can expect to meet with engineers, Data Scientists, Product Managers, hiring managers and a senior Machine Learning Engineer.

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