Dunnhumby Data Scientist Interview Questions and Answers

It was basic with puzzles and sql

Case study about a pharma company entering a new market, customer segmentation and also past projects discussion.

I was asked to write SQL queries for 3rd highest salary of the employee, some name filtering, group by tasks.
Python code to find the index of the maximum number without using numpy.

Q1. Explain the Project undertaken during the research and follow-up questions
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Q1. Write pandas query to separate the names as first and last name from the full name. Drop the duplicate columns and also the missing values. Write output for the Python code. Write SQL query to retrieve t...read more
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Answering questions related to data science concepts and techniques.
• Recall is the ratio of correctly predicted positive observations to the total actual positives. Precision is the ratio of correctly predicted positive observations to the total predicted positives.

• To reduce variance in an ensemble model, techniques like bagging, boosting, and stacking can be used. Bagging involves training multiple models on different ...read more
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Simple Aptitude questions, Data interpretation and verbal

Q1. Basic questions on Data Analytics, Projects mentioned
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Q2. Code in SQL and python(moderate)
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The candidate is asked to code in SQL and Python at a moderate level.
• Use SQL to query data from databases

• Use Python to manipulate and analyze data

• Practice writing SQL queries and Python scripts
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Q3. Machine Learning
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1 hour aptitude test

Q1. What is one hot encoding
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Q1. What is your long term goal
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Q1. Explain the RAG pipeline?
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RAG pipeline is a data processing pipeline used in data science to categorize data into Red, Amber, and Green based on certain criteria.
• RAG stands for Red, Amber, Green which are used to categorize data based on certain criteria

• Red category typically represents data that needs immediate attention or action

• Amber category represents data that requires monitoring or further investigation

• Green category represents data that...read more
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Q2. Explain Confusion metrics
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Confusion metrics are used to evaluate the performance of a classification model by comparing predicted values with actual values.
• Confusion matrix is a table that describes the performance of a classification model.

• It consists of four different metrics: True Positive, True Negative, False Positive, and False Negative.

• These metrics are used to calculate other evaluation metrics like accuracy, precision, recall, and F1 s...read more
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