Data Analyst🔥Technical Interview Questions ✅ | Top 15 Questions with Answers

Summary

In this video, the speaker, a data analyst, shares her personal experiences preparing for and succeeding in data analyst interviews. She covers a range of technical questions commonly asked in interviews, including topics in SQL (e.g., JOINS, DELETE vs DROP vs TRUNCATE), Excel (e.g., Pivot Tables, VLOOKUP, conditional formatting), Python (e.g., Pandas, NumPy, handling missing data), and Statistics (e.g., mean, median, mode, correlation vs causation). The video provides viewers with essential tips, common challenges, and technical insights to excel in their upcoming data analyst interviews.

Takeaways

• 😀 Technical interview questions for data analysts are often focused on SQL, Excel, Python, and Statistics.
• 😀 Familiarize yourself with basic SQL concepts like the difference between WHERE and HAVING, JOINs, and deleting or truncating data.
• 😀 For SQL, be prepared to write queries for common tasks like finding the second highest value in a dataset.
• 😀 Excel skills such as creating Pivot Tables, using VLOOKUP/HLOOKUP, removing duplicates, and applying conditional formatting are essential.
• 😀 Statistics basics such as mean, median, mode, and standard deviation are important for data analysis roles.
• 😀 Understand the distinction between correlation and causation, as this could be a tricky interview question.
• 😀 Python is widely used in data analysis for libraries like Pandas, NumPy, Matplotlib, and Seaborn, so know how and when to use them.
• 😀 Be ready to explain how to handle missing data in Python using methods like fillna() and dropna().
• 😀 Prepare for scenario-based questions, where you might be asked to solve practical data-related problems on the spot.
• 😀 The interviewer may expect you to explain why you prefer Python over R or vice versa, so know the strengths of both languages.
• 😀 The content of the interview might be split between technical skills and general interview questions, so don’t neglect your personal and role-related preparation.

Q & A

What are some of the most common questions asked in a data analyst interview?

Some common questions asked in data analyst interviews include: 'Introduce yourself', 'Why do you want to become a data analyst?', and 'What are your strengths and weaknesses as a data analyst?'. These questions help the interviewer assess your motivation and personal attributes.

What is the difference between the 'WHERE' and 'HAVING' clauses in SQL?

The 'WHERE' clause is used to filter rows before any grouping occurs, while the 'HAVING' clause is used to filter data after grouping is done. The 'HAVING' clause is typically used with aggregate functions like COUNT, SUM, AVG, etc.

How do you perform a join in SQL, and what are the different types of joins?

A join combines data from two or more tables based on a related column. The main types of joins are INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN. Each type determines how unmatched rows are handled.

Can you write a query to find the second highest sale in a city?

Yes, to find the second-highest sale in a city, you can use a query like: 'SELECT MAX(sale) FROM table WHERE sale < (SELECT MAX(sale) FROM table)'. This will return the second-highest sale value from the table.

What is the difference between 'DELETE', 'DROP', and 'TRUNCATE' in SQL?

The 'DELETE' command removes rows from a table but allows you to roll back the operation. The 'DROP' command removes the entire table, including its structure. 'TRUNCATE' removes all rows from a table but is more efficient and cannot be rolled back.

What is a Pivot Table in Excel, and why is it important?

A Pivot Table is an interactive data summary tool in Excel that helps in summarizing, analyzing, exploring, and presenting data. It allows users to extract meaningful insights from large datasets by arranging and aggregating data in various ways.

What is the difference between VLOOKUP and HLOOKUP in Excel?

VLOOKUP is used for looking up data in a vertical column, while HLOOKUP is used for looking up data in a horizontal row. Both functions search for a value in one column or row and return a corresponding value from another column or row.

How would you remove duplicates in an Excel sheet?

You can remove duplicates in Excel using the 'Remove Duplicates' tool found under the 'Data' tab. Alternatively, you can use conditional formatting or a formula-based approach to identify and remove duplicates.

What is the purpose of Conditional Formatting in Excel?

Conditional formatting is used to change the appearance of cells based on specific conditions, such as highlighting the highest or lowest values, identifying duplicates, or applying color scales. It helps to visualize data trends and anomalies.

What is the difference between Pandas and NumPy in Python, and when should each be used?

Pandas is used for data manipulation and analysis, specifically for handling tabular data with labeled axes. NumPy, on the other hand, is used for numerical computations and provides support for large multidimensional arrays. Use Pandas when working with structured data and NumPy for performance-intensive numerical tasks.