1000+ Data Analyst Interview Questions and Answers

Possible reasons for delay in delivery

• Logistical issues such as traffic or weather

• Inadequate inventory management

• Production delays

• Customs clearance delays

• Incorrect address or contact information

• Technical issues with delivery vehicles or equipment

SQL commands are used to manipulate and retrieve data from relational databases.

• SQL stands for Structured Query Language

• Common SQL commands include SELECT, INSERT, UPDATE, and DELETE

• SQL commands are used to create, modify, and delete database objects such as tables, views, and indexes

• Examples: SELECT * FROM customers; INSERT INTO orders (customer_id, order_date) VALUES (1, '2021-01-01'); UPDATE products SET price = 10.99 WHERE id = 1; DELETE FROM customers WHERE id = 1;

Disadvantages of data analytics include potential privacy concerns, data quality issues, and the need for skilled professionals. Data science involves more advanced techniques and focuses on predictive modeling.

• Privacy concerns: Data analytics may involve handling sensitive information, raising privacy issues for individuals or organizations.

• Data quality issues: Inaccurate or incomplete data can lead to incorrect analysis and decision-making.

• Skilled professionals required: Da...read more

Various machine learning algorithms with brief details

• Supervised Learning: Linear Regression, Logistic Regression, Support Vector Machines (SVM), Decision Trees, Random Forest

• Unsupervised Learning: K-means Clustering, Hierarchical Clustering, Principal Component Analysis (PCA)

• Reinforcement Learning: Q-Learning, Deep Q-Networks (DQN)

• Neural Networks: Convolutional Neural Networks (CNN), Recurrent Neural Networks (RNN), Long Short-Term Memory (LSTM)

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

Yes, I am proficient in SQL and my preferred visualization tool is Tableau. My expertise lies in creating interactive dashboards and reports.

• Proficient in SQL and Tableau

• Expertise in creating interactive dashboards and reports

• Familiar with other visualization tools like Power BI and QlikView

• Use best practices like using appropriate chart types and color schemes

• Regularly update and maintain dashboards to ensure accuracy and relevance

AI and machine learning are real technologies with practical applications in various industries.

• AI and machine learning have been successfully used in various industries such as healthcare, finance, and transportation to improve efficiency and accuracy.

• Companies like Google, Amazon, and Facebook heavily rely on AI and machine learning algorithms to enhance their products and services.

• AI and machine learning technologies have shown significant advancements in natural language ...read more

Flat tables can be created using SQL by selecting the desired columns from multiple tables and joining them based on common keys.

• Identify the tables that need to be included in the flat table

• Determine the common keys between the tables

• Use the SELECT statement to choose the desired columns from each table

• Join the tables using the common keys

• Apply any necessary filtering or sorting

• Save the result as a new table or view

As a data analyst for three months, I would be responsible for analyzing data, creating reports, and presenting insights to stakeholders.

• Analyze data to identify trends and patterns

• Create reports and visualizations to communicate insights

• Collaborate with stakeholders to understand their needs and provide recommendations

• Use statistical tools and techniques to validate findings

• Continuously monitor and improve data quality

• Examples: analyzing sales data to identify top-performing...read more

Use Power BI to connect to SQL database, import dataset, and create visualizations

• Connect Power BI to SQL database

• Import dataset from SQL into Power BI

• Create visualizations using the imported data

Use Python to separate portion before and after @ in an email address.

• Use the split() method to separate the email address into two parts based on the @ symbol.

• Access the parts using index 0 for the portion before @ and index 1 for the portion after @.

• Example: email = 'example@email.com'; parts = email.split('@'); before = parts[0]; after = parts[1];

Merge query combines data from two or more tables based on a common column, while append query adds data from one table to the end of another.

• Merge query combines data from multiple tables based on a common column, creating a new result set.

• Append query adds the rows from one table to the end of another table, increasing the total number of rows.

• Merge query is used to combine related data from different sources, while append query is used to add new records to an existing tab...read more

The order of execution in a query determines the sequence in which operations are performed.

• 1. The order of execution in a query typically follows the sequence: FROM, WHERE, GROUP BY, HAVING, SELECT, ORDER BY.

• 2. The FROM clause specifies the tables involved in the query.

• 3. The WHERE clause filters the rows based on specified conditions.

• 4. The GROUP BY clause groups the rows that have the same values into summary rows.

• 5. The HAVING clause filters the groups based on specified ...read more

I prioritize tasks in a data project by assessing deadlines, importance, dependencies, and impact on overall project goals.

• Identify deadlines for each task and prioritize based on urgency

• Consider the importance of each task in relation to project goals

• Take into account dependencies between tasks and prioritize accordingly

• Assess the potential impact of completing each task on the overall project success

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

UNION combines and removes duplicates, UNION ALL combines without removing duplicates.

• UNION merges the result sets of two or more SELECT statements, removing duplicates.

• UNION ALL merges the result sets of two or more SELECT statements, including duplicates.

• UNION is slower than UNION ALL as it involves removing duplicates.

• Example: SELECT column1 FROM table1 UNION SELECT column1 FROM table2;

• Example: SELECT column1 FROM table1 UNION ALL SELECT column1 FROM table2;

The LIKE operator is used in SQL to search for a specified pattern in a column.

• The LIKE operator is used with the WHERE clause to search for a specified pattern in a column.

• It allows for the use of wildcards such as % (matches any sequence of characters) and _ (matches any single character).

• For example, 'SELECT * FROM table_name WHERE column_name LIKE 'a%'' will return all rows where the column starts with 'a'.

Cross over studies are designed to compare two or more treatments on the same group of subjects.

• Subjects receive one treatment for a certain period of time, then switch to another treatment.

• The order of treatments is randomized to avoid bias.

• The washout period between treatments is important to eliminate carryover effects.

• Data is analyzed using paired t-tests or ANOVA.

• Interpretation of results should consider carryover effects and treatment order.

• Example: comparing the effect...read more

Overview of oncology including cancer stages, TNM staging system, cancer grades, types of cancer treatment, and types of cancer.

• Cancer stages range from 0 to IV, with higher numbers indicating more advanced cancer

• TNM staging system is used to describe the extent of cancer in a patient's body

• Cancer grades range from 1 to 4, with higher numbers indicating more abnormal cells

• Types of cancer treatment include surgery, chemotherapy, radiation therapy, immunotherapy, and targeted t...read more

Impairment is the reduction in the value of an asset due to damage, obsolescence, or other factors.

• Impairment is a decrease in the value of an asset.

• It can be caused by physical damage, obsolescence, or changes in market conditions.

• The impairment process involves assessing the asset's current value and comparing it to its original cost.

• If the current value is lower, the asset is impaired and its value is adjusted accordingly.

• Impairment can be temporary or permanent, and can a...read more

Yes, I have experience working in cloud environments.

• I have worked with AWS, Azure, and Google Cloud Platform.

• I have experience with cloud-based data storage and processing.

• I have used cloud-based tools for data visualization and analysis.

• I am familiar with cloud security and compliance measures.

To retrieve data over 3 months in a dynamic dashboard, use a date range filter and ensure the data source is updated regularly.

• Create a date range filter in the dashboard to select a time period of over 3 months

• Ensure the data source is updated regularly to include the required data

• Use SQL queries or data extraction tools to pull the necessary data for the dashboard

• Consider automating the data retrieval process to ensure accuracy and efficiency

A Dicreat Chart is a type of chart that displays data points in a discrete manner, typically using bars or columns.

• Dicreat Charts are used to represent categorical data, where each category is represented by a separate bar or column.

• They are commonly used in market research, survey data analysis, and comparison of different categories.

• Examples of Dicreat Charts include bar charts, column charts, and stacked bar charts.

Query to retrieve employee names who joined in last 30 days

• Use the current date and subtract 30 days to get the date 30 days ago

• Join the employee table with the date joined column to filter employees who joined in the last 30 days

I have worked on databases such as MySQL, SQL Server, and MongoDB.

• MySQL

• SQL Server

• MongoDB

Yes, I have technical certifications and I am proficient in multiple programming languages.

• I have a certification in SQL from Oracle

• I am proficient in Python, R, and Java

• I have experience with data visualization tools like Tableau and Power BI

Multicollinearity is a phenomenon where two or more independent variables in a regression model are highly correlated.

• It can lead to unstable and unreliable estimates of regression coefficients.

• It can make it difficult to determine the individual effect of each independent variable on the dependent variable.

• It can also result in inflated standard errors and p-values, making it difficult to identify statistically significant variables.

• It can be detected using methods such as c...read more

I prioritize tasks based on deadlines and importance, utilizing to-do lists and time management techniques.

• Prioritize tasks based on deadlines and importance

• Utilize to-do lists to keep track of tasks

• Use time management techniques such as the Pomodoro technique

• Delegate tasks when possible to lighten the workload

I will streamline the process by identifying bottlenecks and implementing automation.

• Analyze current process flow

• Identify areas of delay or inefficiency

• Implement automation tools to reduce manual effort

• Set up clear communication channels between team members

• Track progress and adjust as needed

SQL is a programming language used to manage relational databases. RDBMS is a software used to manage databases. Non-SQL tools are alternatives to SQL. Schema is a blueprint of a database.

• SQL is used to manage relational databases

• RDBMS is a software used to manage databases

• Non-SQL tools are alternatives to SQL, such as NoSQL databases

• Schema is a blueprint of a database, defining its structure and relationships

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.

DAX (Data Analysis Expressions) is a formula language used in Power BI to create custom calculations and aggregations.

• DAX functions are used to create calculated columns, measures, and calculated tables in Power BI.

• DAX functions can perform various operations like mathematical calculations, logical comparisons, and text manipulation.

• Examples of DAX functions include SUM, AVERAGE, CALCULATE, FILTER, and RELATED.

A measure is a calculation based on the data model, while a calculated column is a new column created in the data model.

• Measures are dynamic and calculated on the fly, while calculated columns are static and stored in the data model.

• Measures are used for aggregations and calculations, while calculated columns are used for adding new data columns.

• Measures are typically used in visualizations, while calculated columns are used for filtering and sorting.

• Example: A measure could ...read more

I have extensive experience in data analysis using tools such as Excel, SQL, Python, and Tableau.

• Proficient in Excel for data cleaning, manipulation, and visualization

• Strong SQL skills for querying databases and extracting relevant information

• Experience with Python for statistical analysis and machine learning

• Familiarity with Tableau for creating interactive dashboards and reports

Variables importance in predictive model is determined using techniques like feature selection, correlation analysis, and machine learning algorithms.

• Use feature selection techniques like Recursive Feature Elimination (RFE) or SelectKBest to identify important variables.

• Analyze correlation between variables and target variable to determine importance.

• Utilize machine learning algorithms like Random Forest or Gradient Boosting to rank variables based on their impact on model pe...read more

I have extensive experience with API integration in Thoughtspot.

• Developed custom API integrations to pull data from external sources into Thoughtspot

• Utilized Thoughtspot's REST API to automate data loading and report generation

• Worked closely with IT teams to troubleshoot and optimize API connections

Charts are used to represent data visually. Different types of charts are used based on the type of data and purpose.

• Line charts for showing trends over time

• Bar charts for comparing values

• Pie charts for showing proportions

• Scatter plots for showing relationships between variables

• Heat maps for showing density or distribution

• Histograms for showing frequency distribution

• Box plots for showing distribution and outliers

• Gantt charts for showing project timelines

The time taken to update hundred banks will depend on various factors such as the complexity of updates, resources available, and efficiency of the process.

• Time taken will depend on the size and complexity of updates needed for each bank.

• Efficiency of the process and resources available will also impact the time taken.

• For example, if each bank requires a simple update that can be done quickly, it may take less time compared to complex updates that require more time and resour...read more

To confirm a location, I would look for consistency in multiple data points such as address, coordinates, landmarks, and geotags.

• Verify the address provided matches with known landmarks or businesses in the area

• Check the coordinates provided against mapping services like Google Maps

• Look for geotags or location data associated with photos or social media posts

• Confirm the location using street view images or satellite imagery

I use a variety of visualizations such as bar charts, line graphs, scatter plots, and heat maps depending on the type of data and context.

• Bar charts are useful for comparing categories of data

• Line graphs are great for showing trends over time

• Scatter plots help in identifying relationships between variables

• Heat maps are effective for visualizing large datasets and identifying patterns

Tokens in Postgres are the smallest unit of input that can be processed by the parser.

• Tokens are used to identify and categorize the different parts of a SQL statement.

• Examples of tokens include keywords, identifiers, operators, and literals.

• The parser uses tokens to create a parse tree, which is used to execute the SQL statement.

WASO is Wake After Sleep Onset, TSO is Total Sleep Time, and EPS is Earnings Per Share.

• WASO is the amount of time spent awake after initially falling asleep.

• TSO is the total amount of time spent sleeping, including both REM and non-REM sleep.

• EPS is a financial metric that represents the portion of a company's profit allocated to each outstanding share of common stock.

• WASO and TSO are commonly used in sleep studies, while EPS is used in financial analysis.

Various methods such as visual inspection, mathematical algorithms, and statistical techniques are used to identify the peak and trough of a signal.

• Visual inspection of the signal waveform to identify the highest point as the peak and the lowest point as the trough.

• Mathematical algorithms like finding the derivative of the signal and locating the points where it equals zero to identify peaks and troughs.

• Statistical techniques such as moving average or peak detection algorithm...read more

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

A Pivot Table is a data summarization tool used in spreadsheet programs to analyze, summarize, and present data in a tabular format.

• Pivot tables allow users to reorganize and summarize selected columns and rows of data to obtain desired insights.

• Users can easily group and filter data, perform calculations, and create visualizations using pivot tables.

• Pivot tables are commonly used in Excel and other spreadsheet programs for data analysis and reporting.

• For example, a sales man...read more

The total number of flowers accumulated at the end of the day can be calculated by multiplying the number of people by the number of flowers each person offers.

• Multiply the number of people by 5 to get the total number of flowers accumulated

• For example, if there are 10 people, the total number of flowers accumulated would be 10 * 5 = 50

Star and dimension schema are used in data warehousing to organize data, while window functions in SQL are used for analytical queries.

• Star schema is a type of schema where a central fact table is connected to multiple dimension tables.

• Dimension schema is a type of schema where each dimension is represented by a separate table.

• Window functions in SQL are used to perform calculations across a set of table rows related to the current row.

• Examples of window functions include ROW...read more