Subex Data Scientist Interview Questions and Answers

Q1. Difference between Precision and Recall? How to select features? What’s p-value?
Ans. 
Precision and Recall are evaluation metrics for classification models. Feature selection is important for model performance. P-value is a statistical measure.
• Precision is the ratio of true positives to the total predicted positives. Recall is the ratio of true positives to the total actual positives.

• Precision is important when false positives are costly, while recall is important when false negatives are costly.

• Feature...read more
Answered by AI
Add your answer

Q1. Questions on project life cycle: Challenges faced during Data Cleaning and Feature Engineering?
Add your answer

Q1. What is Machine Learning, Difference among AI, ML and DL
Ans. 
Machine Learning is a subset of Artificial Intelligence that uses algorithms to learn from data and make predictions.
• AI (Artificial Intelligence) is the broader concept of machines being able to carry out tasks in a way that we would consider 'smart'.

• ML (Machine Learning) is a subset of AI that focuses on the development of computer programs that can access data and use it to learn for themselves.

• DL (Deep Learning) is ...read more
Answered by AI
Add your answer
Q2. Evaluation Metrics for Classification
Ans. 
Evaluation metrics are used to assess the performance of classification models.
• Common evaluation metrics include accuracy, precision, recall, F1 score, and ROC-AUC.

• Accuracy measures the overall correctness of the model's predictions.

• Precision measures the proportion of true positive predictions out of all positive predictions.

• Recall measures the proportion of true positive predictions out of all actual positives.

• F1 sco...read more
Answered by AI
Add your answer

Q1. Window Function of SQL
Ans. 
Window functions in SQL allow you to perform calculations across a set of table rows related to the current row.
• Window functions are used to perform calculations on a set of rows related to the current row.

• They do not reduce the number of rows returned by the query.

• Common window functions include ROW_NUMBER(), RANK(), DENSE_RANK(), and NTILE().
Answered by AI
Add your answer
Q2. Index and Procedure in SQL
Ans. 
Indexes are used to improve the performance of SQL queries by allowing faster data retrieval. Procedures are reusable SQL code blocks.
• Indexes are used to quickly locate data without having to scan the entire table.

• Procedures are stored SQL code blocks that can be executed multiple times.

• Indexes can be created on columns to speed up search queries.

• Procedures can accept input parameters and return results.
Answered by AI
Add your answer

Q1. Salary Expectation
Add your answer
Q2. Location Preferemce
Add your answer

Q1. Questions on self join
Add your answer

HackerEarth based assessment.
1. 8 qs were stats & prob based multiples choices
2. 2 were medium level sql questions.

Q1. Started with basic sql question like diff btw nosql & sql, join etc
Add your answer
Q2. Table were given in google sheet & had to write basic level queries on them eg. cte's, agg function, lead & lag func
Ans. 
Basic SQL queries using CTEs, aggregate functions, and window functions like LEAD and LAG in Google Sheets.
• CTE (Common Table Expression) allows you to define a temporary result set. Example: WITH SalesCTE AS (SELECT * FROM Sales) SELECT * FROM SalesCTE;

• Aggregate functions like COUNT, SUM, AVG help summarize data. Example: SELECT COUNT(*) FROM Orders WHERE Status = 'Completed';

• LEAD function retrieves the next row's valu...read more
Answered by AI
Add your answer

Q1. The interviewer was not serious at all, asked silly quizzes instead of business case study, KPI & metrics
Add your answer
Q2. Prepare for logical reasoning
Add your answer

Consisted of 10 questions, 2 SQL medium level questions and remaining easy aptitude, profit loss, work time etc

Q1. SQL visualisation
Add your answer
Q2. SQL Questions theory
Add your answer

6 mcqs and 2 sql questions

Q1. Difference between having and where in sql
Add your answer
Q2. Sql joins and it types
Add your answer
Q3. Window functions and subqueries
Add your answer
Q4. Sql scenario question based on joins
Add your answer
Q5. Kpi's and metrics
Add your answer

Q1. Business problem related to case study
Add your answer

Basic Hacker Rank SQL Questions 2 . and 10 MCQ based

Q1. Select customer, sum(amt ) as total_amt from t1 group by customer how many no. of rows it will return and explain this table t1 column name-> dept customer item amt
Add your answer
Q2. Select * , sum(amt) over (partition by customer) as total_amt from t2
Ans. 
The query selects all columns and calculates the total amount for each customer in table t2.
• The query uses a window function to calculate the sum of 'amt' for each customer in the 't2' table.

• The 'partition by customer' clause divides the result set into partitions based on the 'customer' column.

• The 'select *' statement selects all columns from the table along with the calculated total amount.

• The 'sum(amt) over (partiti...read more
Answered by AI
Add your answer
Q3. How many Customers has purchased same item on the Same day more than onnce
Ans. 
To find customers who purchased the same item multiple times on the same day.
• Identify unique customers who purchased the same item multiple times on the same day

• Check for duplicate transactions by customer and item on the same day

• Aggregate the data to count the number of customers who made multiple purchases of the same item on the same day
Answered by AI
Add your answer

Knowledge. Creative. Innovative

Knowledge new idea reach target reach gaol
Idea screening

Q1. New innovative.... Profit earn.. Reach goal
Add your answer

Mats knowledge ...creative... Idea