1500+ Data Analyst Interview Questions and Answers

Sharing data insights can help improve services and identify revenue opportunities.

• Analyzing customer behavior can help identify areas for improvement

• Identifying trends in sales data can help optimize pricing strategies

• Using data to personalize marketing efforts can increase customer engagement

• Predictive modeling can help identify potential revenue opportunities

• Tracking key performance indicators can help optimize business operations

It is impossible to accurately determine the number of cups of tea consumed in Delhi for a week without proper data.

• There is no official data available on the exact number of cups of tea consumed in Delhi for a week.

• The number of cups of tea consumed in Delhi for a week varies depending on various factors such as weather, season, and individual preferences.

• It is estimated that Delhi consumes a significant amount of tea due to its cultural and historical significance.

• Factors s...read more

Separate the first two letters from strings with matching prefixes using SQL string functions.

• Use the LEFT function to extract the first two letters: LEFT(name, 2).

• Use the SUBSTRING function to get the remaining part: SUBSTRING(name, 3, LEN(name)).

• Combine these functions in a SELECT statement to display both parts.

• Example: For names 'Alice', 'Alfred', 'Bob', 'Charlie', the output will be: ('Al', 'ice'), ('Al', 'fred'), ('Bo', 'b'), ('Ch', 'arlie').

Calculate the percentage of the first transaction compared to subsequent transactions using a simple formula.

• Identify the first transaction amount (e.g., $100).

• Sum the amounts of all subsequent transactions (e.g., $200 + $150 = $350).

• Use the formula: (First Transaction / Total Subsequent Transactions) * 100.

• Example: ($100 / $350) * 100 = 28.57%.

• This percentage indicates the first transaction's contribution to the total.

Asking for clarification shows engagement and interest in the conversation.

• Asking for clarification demonstrates active listening and a desire to fully understand the topic.

• It can also help clarify any misunderstandings or uncertainties, leading to more productive discussions.

• Examples: 'Could you please explain that concept in more detail?' or 'I'm not sure I understand, could you provide an example?'

No, regression is used for predicting continuous values, while classification is used for predicting categorical values.

• Regression predicts continuous values, while classification predicts categorical values

• Regression models include linear regression, polynomial regression, etc.

• Classification models include logistic regression, decision trees, etc.

Create calculated fields in Tableau to dynamically adjust to changing table columns.

• Use calculated fields to reference specific columns by name instead of position.

• Utilize parameters to allow users to select which columns to display.

• Consider using custom SQL queries to dynamically adjust to changing table structure.

OOPS stands for Object-Oriented Programming. The 4 pillars of OOPS are Inheritance, Encapsulation, Abstraction, and Polymorphism.

• OOPS stands for Object-Oriented Programming

• 4 pillars of OOPS are Inheritance, Encapsulation, Abstraction, and Polymorphism

• Polymorphism allows objects of different classes to be treated as objects of a common superclass

• Example: Sorting an array of strings in ascending order - ['apple', 'banana', 'cherry']

• Example: Sorting an array of strings in descen...read more

SQL joins are used to combine rows from different tables based on a related column between them.

• Types of SQL joins include inner join, left join, right join, and full outer join.

• Inner join returns only the matching rows from both tables.

• Left join returns all rows from the left table and the matching rows from the right table.

• Right join returns all rows from the right table and the matching rows from the left table.

• Full outer join returns all rows from both tables, including u...read more

Freshers in data analyst roles typically handle data collection, cleaning, and basic analysis tasks to support decision-making.

• Data Collection: Gathering data from various sources, such as databases or surveys.

• Data Cleaning: Identifying and correcting errors in datasets to ensure accuracy.

• Basic Analysis: Performing simple statistical analyses to derive insights, like calculating averages or trends.

• Reporting: Creating visualizations and reports to present findings to stakehold...read more

It is impossible to accurately estimate the number of women driving red cars in Bangalore without specific data.

• There is no specific data available on the number of women driving red cars in Bangalore.

• Estimating the number of women driving red cars in Bangalore would require access to vehicle registration data or a survey of car owners.

• Factors such as car ownership trends among women and the popularity of red cars would also impact the estimate.

Regression predicts continuous values while classification predicts categorical values.

• Regression is used to predict a continuous output variable based on one or more input variables.

• Classification is used to predict a categorical output variable based on one or more input variables.

• Regression algorithms include linear regression, polynomial regression, and logistic regression.

• Classification algorithms include decision trees, random forests, and support vector machines.

• Exampl...read more

Developed a script for forecasting using KNN and data science models.

• Developed a script using Python to forecast sales for a retail company using KNN algorithm.

• Built a data science model to predict customer churn for a telecom company using logistic regression.

• Used time series analysis to forecast stock prices for a financial services company.

• Developed a script to predict the likelihood of a customer defaulting on a loan using decision trees.

• Implemented a recommendation syste...read more

Python code to retrieve common rows from two tables

• Use pandas library to read tables and perform operations

• Merge the two tables using a common column

• Filter the merged table to get common rows

Using CASE WHEN in SQL to categorize data based on specific conditions.

• CASE WHEN can be used to create new columns based on conditions.

• Example: SELECT name, CASE WHEN age < 18 THEN 'Minor' ELSE 'Adult' END AS age_group FROM users;

• It allows for multiple conditions: CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ELSE result END.

• Useful for data transformation and reporting.

I don't have the available data to answer the question.

A case study on the number of green T-shirts sold in the US.

• Identify the target audience for green T-shirts

• Analyze the market demand for green T-shirts

• Study the sales data of green T-shirts in the US

• Identify the popular brands and styles of green T-shirts

• Analyze the impact of seasonality on sales

• Consider the pricing strategy of green T-shirts

• Identify potential marketing opportunities to increase sales

Logistic regression is a type of classifier that uses a logistic function to model a binary dependent variable.

• Logistic regression is a statistical method used to analyze a dataset in which there are one or more independent variables that determine an outcome.

• It is called logistic regression because it uses a logistic function to model a binary dependent variable.

• The logistic function is an S-shaped curve that can take any real-valued number and map it into a value between 0 ...read more

Python is not an awful language, but I am open to working with other technologies like Spring or Node.

• Python is a versatile and widely-used language in data analysis and machine learning.

• It has a large community and extensive libraries like Pandas and NumPy.

• Spring and Node are also popular choices for backend development, offering different strengths and capabilities.

• I am open to learning and working with new technologies to expand my skill set.

Fill 4L water in 3L and 5L capacity vessels

• Fill 3L vessel completely

• Pour the water from 3L vessel into 5L vessel

• Fill 3L vessel again

• Pour the water from 3L vessel into 5L vessel until it's full

• The remaining water in 3L vessel is 1L

The Steel Making Process and Prerequisites for Making a Steel Water Bottle

• The steel making process involves converting iron ore into steel through various stages such as smelting, refining, and casting

• Prerequisites for making a steel water bottle include obtaining high-quality steel, designing the bottle, and manufacturing it through processes such as stamping and welding

• The Hall Herault process is a method for producing aluminum through the electrolysis of alumina dissolved ...read more

Formula is a mathematical expression while function is a pre-built formula that performs a specific task.

• Formula is a combination of mathematical operators and values used to calculate a result.

• Function is a pre-built formula that performs a specific task, such as finding the average of a range of numbers.

• Formulas can be customized and modified, while functions are fixed and cannot be changed.

• Examples of functions include SUM, AVERAGE, MAX, MIN, etc.

DELETE is used to remove rows from a table, while DROP is used to remove entire tables from a database.

• DELETE is a DML command used to remove specific rows from a table based on a condition.

• DROP is a DDL command used to remove entire tables, views, or databases from a database.

• DELETE does not remove the table structure, only the data within it.

• DROP removes the table structure along with all its data, and it cannot be rolled back.

• Example: DELETE FROM table_name WHERE condition...read more

Data analysis is crucial for making informed decisions. Tokopedia's vast data provides a great opportunity for analysis. My bachelor's thesis focused on data-driven insights.

• Data allows for informed decision-making and insights.

• Tokopedia's extensive data provides a valuable opportunity for analysis.

• My bachelor's thesis delved into data-driven insights and analysis.

Use SQL query with window functions like ROW_NUMBER() to select consecutive data from a column

• Use ROW_NUMBER() to assign a unique number to each row based on a specific order

• Use a self join or subquery to compare the row numbers of consecutive rows

• Filter the rows where the row numbers are consecutive to select the consecutive data

SQL joins are used to combine data from two or more tables. Left Outer Join returns all the rows from the left table and matching rows from the right table.

• Joins are used to combine data from two or more tables in SQL

• Common types of joins are Inner Join, Left Outer Join, Right Outer Join, and Full Outer Join

• Left Outer Join returns all the rows from the left table and matching rows from the right table

• Syntax: SELECT * FROM table1 LEFT JOIN table2 ON table1.column = table2.colu...read more

Dcount function counts the number of unique values in a dataset. ABS function returns the absolute value of a number. To remove minus sign from an integer in Excel, use a formula like =ABS(A1).

• Dcount function counts unique values in a dataset

• ABS function returns absolute value of a number

• To remove minus sign from an integer in Excel, use formula like =ABS(A1)