C2fo Decision Scientist Interview Questions, Process, and Tips

Q1. What is Vlookup and Hlookup
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Q1. General ml questions
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Q2. Coding on dataframe from kaggle
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Q1. What is the SQL query for calculating a moving average?
Ans. 
The SQL query for calculating a moving average involves using window functions.
• Use the OVER clause with the ORDER BY clause to define the window frame for the moving average calculation.

• Use the AVG() function to calculate the average within the window frame.

• Example: SELECT value, AVG(value) OVER (ORDER BY date ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) AS moving_avg FROM table_name;
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Q2. What is the difference between Data Definition Language (DDL) and Data Manipulation Language (DML)?
Ans. 
DDL is used to define the structure of database objects, while DML is used to manipulate data within those objects.
• DDL is used to create, modify, and delete database objects such as tables, indexes, and views.

• DML is used to insert, update, retrieve, and delete data within those database objects.

• Examples of DDL statements include CREATE TABLE, ALTER INDEX, and DROP VIEW.

• Examples of DML statements include INSERT INTO, UP
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Q1. Questions on my Undergraduate and last employment projects. Hackerrank coding round: 2 questions (easy-medium level) Hackerrank Sql round: 2 questions (easy-medium level; window function)
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Q2. Explain working of recommendation system.
Ans. 
Recommendation system uses data analysis and machine learning algorithms to suggest items to users based on their preferences.
• Collect user data and item data

• Analyze data to find patterns and similarities

• Use machine learning algorithms to make predictions and suggest items to users

• Continuously update and improve the system based on user feedback

• Examples: Netflix suggesting movies based on viewing history, Amazon suggest
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Q1. What is difference between delete,drop and truncate. ?
Ans. 
Delete removes specific rows from a table, drop removes entire table structure, and truncate removes all rows from a table.
• Delete is a DML command, drop is a DDL command, and truncate is a DDL command.

• Delete can be rolled back, drop cannot be rolled back, and truncate cannot be rolled back.

• Delete triggers delete triggers, drop triggers drop triggers, and truncate does not trigger any triggers.

• Example: DELETE FROM table...read more
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Q1. What are iterrators .?
Ans. 
Iterators are objects that allow sequential access to elements in a collection.
• Iterators are used to loop through elements in a collection one at a time.

• They provide a way to access elements without exposing the underlying data structure.

• Iterators have methods like next() to retrieve the next element in the collection.

• Examples of iterators include Python's iter() and Java's Iterator interface.
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Python coding 45 mins

Q1. Fraud data balancing
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Q2. Recommendation metrics
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Q1. Why join Turing?
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Q2. Ability to learn new skills
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Assignment containing the python coding and the pandas data analysis and statistics questions

Q1. Given the tabular data and asked to find the issues in the data and how to solve them.
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Q2. Check if the sentence is palindrome or not.
Ans. 
Check if a sentence is a palindrome or not.
• Remove all non-alphanumeric characters and convert to lowercase.

• Compare the original sentence with its reverse to check for palindrome.

• Example: 'A man, a plan, a canal, Panama' is a palindrome sentence.
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Q1. Classical data science questions
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Q2. Given the large dataset and asked to find the answers using pandas
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A simple Python coding assesment - had fibonacci series and just general python questions

Q1. Probablity Question - Coin toss one
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Q2. Statistical Significance - what it is? and how to use hypothesis testing
Ans. 
Statistical significance refers to the likelihood that a result or relationship is not due to chance.
• Statistical significance is a measure of the probability that a relationship between variables is not due to random chance.

• Hypothesis testing is a common method to determine statistical significance by comparing observed data to what would be expected by chance.

• A p-value is used to determine statistical significance, wi...read more
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