Data Analyst Interview Resources
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Can you use Chat GPT as a data analyst?

The answer to this question is yes, but you need to be cautious about using Chat GPT on the job (and even while learning analytics) for the following reasons.

1. Chat GPT gets things wrong. A lot.

If you use Chat GPT to write code, you better know that coding language extremely well, because you gotta be able to fact check and alter the response you get from Chat GPT.

For this reason, I would recommend staying away from Chat GPT when you’re learning SQL, Python, etc so you thoroughly learn the code without becoming dependent on AI.

2. You absolutely CANNOT paste company data into Chat GPT

As data analysts we work with highly confidential data that we must exercise great caution to protect.

For this reason, no matter how secure Chat GPT says it is, you must never paste company data into the application.

3. Some companies and bosses may not allow the use of Chat GPT

This is a reality in the world of tech and data since the avalanche of AI tools and features over the last couple years.

I’ve heard of some companies that block Chat GPT altogether, and some managers who advise against using it out of fears for security and other reasons.

Given all three of these reasons, feel free to play around with Chat GPT and AI and learn about them, but don’t become overly dependent on these tools.
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Data Storytelling
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Essential Python and SQL topics for data analysts 😄👇

Python Topics:

Python Resources - @pythonanalyst

1. Data Structures
   - Lists, Tuples, and Dictionaries
   - NumPy Arrays for numerical data

2. Data Manipulation
   - Pandas DataFrames for structured data
   - Data Cleaning and Preprocessing techniques
   - Data Transformation and Reshaping

3. Data Visualization
   - Matplotlib for basic plotting
   - Seaborn for statistical visualizations
   - Plotly for interactive charts

4. Statistical Analysis
   - Descriptive Statistics
   - Hypothesis Testing
   - Regression Analysis

5. Machine Learning
   - Scikit-Learn for machine learning models
   - Model Building, Training, and Evaluation
   - Feature Engineering and Selection

6. Time Series Analysis
   - Handling Time Series Data
   - Time Series Forecasting
   - Anomaly Detection

7. Python Fundamentals
   - Control Flow (if statements, loops)
   - Functions and Modular Code
   - Exception Handling
   - File

SQL Topics:

SQL Resources - @sqlanalyst

1. SQL Basics
- SQL Syntax
- SELECT Queries
- Filters

2. Data Retrieval
- Aggregation Functions (SUM, AVG, COUNT)
- GROUP BY

3. Data Filtering
- WHERE Clause
- ORDER BY

4. Data Joins
- JOIN Operations
- Subqueries

5. Advanced SQL
- Window Functions
- Indexing
- Performance Optimization

6. Database Management
- Connecting to Databases
- SQLAlchemy

7. Database Design
- Data Types
- Normalization

Remember, it's highly likely that you won't know all these concepts from the start. Data analysis is a journey where the more you learn, the more you grow. Embrace the learning process, and your skills will continually evolve and expand. Keep up the great work!

Share with credits: https://t.iss.one/sqlspecialist

Hope it helps :)
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1. What is RDBMS? How is it different from DBMS?

RDBMS stands for Relational Database Management System that stores data in the form of a collection of tables, and relations can be defined between the common fields of these tables.

2.What is ETL in SQL?

ETL stands for Extract, Transform and Load. It is a three-step process, where we would have to start off by extracting the data from sources. Once we collate the data from different sources, what we have is raw data. This raw data has to be transformed into the tidy format, which will come in the second phase.Finally, we would have to load this tidy data into tools which would help us to find insights.




3. What is a kernel function in SVM?


In the SVM algorithm, a kernel function is a special mathematical function. In simple terms, a kernel function takes data as input and converts it into a required form. This transformation of the data is based on something called a kernel trick, which is what gives the kernel function its name. Using the kernel function, we can transform the data that is not linearly separable (cannot be separated using a straight line) into one that is linearly separable.


4. What do you understand by the F1 score?

The F1 score represents the measurement of a model's performance. It is referred to as a weighted average of the precision and recall of a model. The results tending to 1 are considered as the best, and those tending to 0 are the worst. It could be used in classification tests, where true negatives don't matter much.
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Creating a one-month data analytics roadmap requires a focused approach to cover essential concepts and skills. Here's a structured plan along with free resources:

🗓️Week 1: Foundation of Data Analytics

Day 1-2: Basics of Data Analytics
Resource: Khan Academy's Introduction to Statistics
Focus Areas: Understand descriptive statistics, types of data, and data distributions.

Day 3-4: Excel for Data Analysis
Resource: Microsoft Excel tutorials on YouTube or Excel Easy
Focus Areas: Learn essential Excel functions for data manipulation and analysis.

Day 5-7: Introduction to Python for Data Analysis
Resource: Codecademy's Python course or Google's Python Class
Focus Areas: Basic Python syntax, data structures, and libraries like NumPy and Pandas.

🗓️Week 2: Intermediate Data Analytics Skills

Day 8-10: Data Visualization
Resource: Data Visualization with Matplotlib and Seaborn tutorials
Focus Areas: Creating effective charts and graphs to communicate insights.

Day 11-12: Exploratory Data Analysis (EDA)
Resource: Towards Data Science articles on EDA techniques
Focus Areas: Techniques to summarize and explore datasets.

Day 13-14: SQL Fundamentals
Resource: Mode Analytics SQL Tutorial or SQLZoo
Focus Areas: Writing SQL queries for data manipulation.

🗓️Week 3: Advanced Techniques and Tools

Day 15-17: Machine Learning Basics
Resource: Andrew Ng's Machine Learning course on Coursera
Focus Areas: Understand key ML concepts like supervised learning and evaluation metrics.

Day 18-20: Data Cleaning and Preprocessing
Resource: Data Cleaning with Python by Packt
Focus Areas: Techniques to handle missing data, outliers, and normalization.

Day 21-22: Introduction to Big Data
Resource: Big Data University's courses on Hadoop and Spark
Focus Areas: Basics of distributed computing and big data technologies.


🗓️Week 4: Projects and Practice

Day 23-25: Real-World Data Analytics Projects
Resource: Kaggle datasets and competitions
Focus Areas: Apply learned skills to solve practical problems.

Day 26-28: Online Webinars and Community Engagement
Resource: Data Science meetups and webinars (Meetup.com, Eventbrite)
Focus Areas: Networking and learning from industry experts.


Day 29-30: Portfolio Building and Review
Activity: Create a GitHub repository showcasing projects and code
Focus Areas: Present projects and skills effectively for job applications.

👉Additional Resources:
Books: "Python for Data Analysis" by Wes McKinney, "Data Science from Scratch" by Joel Grus.
Online Platforms: DataSimplifier, Kaggle, Towards Data Science

Tailor this roadmap to your learning pace and adjust the resources based on your preferences. Consistent practice and hands-on projects are crucial for mastering data analytics within a month. Good luck!
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Data Analyst Interview questions

Explain the Data Analysis Process:
The data analysis process typically involves several key steps. These steps include:
Data Collection: Gathering the relevant data from various sources.
Data Cleaning: Removing inconsistencies, handling missing values, and ensuring data quality.
Data Exploration: Using descriptive statistics, visualizations, and initial insights to understand the data.
Data Transformation: Preprocessing, feature engineering, and data formatting.
Data Modeling: Applying statistical or machine learning models to extract patterns or make predictions.
Evaluation: Assessing the model's performance and validity.
Interpretation: Drawing meaningful conclusions from the analysis.
Communication: Presenting findings to stakeholders effectively.

What is the Difference Between Descriptive and Inferential Statistics?:
Descriptive statistics summarize and describe data, providing insights into its main characteristics. Examples include measures like mean, median, and standard deviation.
Inferential statistics, on the other hand, involve making predictions or drawing conclusions about a population based on a sample of data. Hypothesis testing and confidence intervals are common inferential statistical techniques.

How Do You Handle Missing Data in a Dataset?:
Handling missing data is crucial for accurate analysis:
I start by identifying the extent of missing data.
For numerical data, I might impute missing values with the mean, median, or a predictive model.
For categorical data, I often use mode imputation.
If appropriate, I consider removing rows with too much missing data.
I also explore if the missingness pattern itself holds valuable information.

What is Exploratory Data Analysis (EDA)?:
EDA is the process of visually and statistically exploring a dataset to understand its characteristics:
I begin with summary statistics, histograms, and box plots to identify data trends.
I create scatterplots and correlation matrices to understand relationships.
Outlier detection and data distribution analysis are also part of EDA.
The goal is to gain insights, identify patterns, and inform subsequent analysis steps.

Give an Example of a Time When You Used Data Analysis to Solve a Real-World Problem:
In a previous role, I worked for an e-commerce company, and we wanted to reduce shopping cart abandonment rates. I conducted a data analysis project:
Collected user data, including browsing behavior, demographics, and purchase history.
Cleaned and preprocessed the data.
Explored the data through visualizations and statistical tests.
Built a predictive model to identify factors contributing to cart abandonment.
Found that longer page load times were a significant factor.
Proposed optimizations to reduce load times, resulting in a 15% decrease in cart abandonment rates over a quarter.

Hope it helps :)
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1. What is Density-based Clustering?

Density-Based Clustering is an unsupervised machine learning method that identifies different groups or clusters in the data space. These clustering techniques are based on the concept that a cluster in the data space is a contiguous region of high point density, separated from other such clusters by contiguous regions of low point density.

Partition-based(K-means) and Hierarchical clustering techniques are highly efficient with normal-shaped clusters while density-based techniques are efficient in arbitrary-shaped clusters or detecting outliers.

2. How to create empty tables with the same structure as another table?

To create empty tables:
Using the INTO operator to fetch the records of one table into a new table while setting a WHERE clause to false for all entries, it is possible to create empty tables with the same structure. As a result, SQL creates a new table with a duplicate structure to accept the fetched entries, but nothing is stored into the new table since the WHERE clause is active.

3. What is a Parameter in Tableau? Give an Example.

A parameter is a dynamic value that a customer could select, and you can use it to replace constant values in calculations, filters, and reference lines.

For example, when creating a filter to show the top 10 products based on total profit instead of the fixed value, you can update the filter to show the top 10, 20, or 30 products using a parameter.

4. How will you write the formula for the following in Excel? - Multiply the value in cell A1 by 10, add the result by 5, and divide it by 2.

To write a formula for the above-stated question, we have to follow the PEDMAS Precedence. The correct answer is ((A1*10)+5)/2.

Answers such as =A1*10+5/2 and =(A1*10)+5/2 are not correct. We must put parentheses brackets after a particular operation.

5. How can you remove duplicate values in a range of cells?

1. To delete duplicate values in a column, select the highlighted cells, and press the delete button. After deleting the values, go to the ‘Conditional Formatting’ option present in the Home tab. Choose ‘Clear Rules’ to remove the rules from the sheet. 2. You can also delete duplicate values by selecting the ‘Remove Duplicates’ option under Data Tools present in the Data tab.
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Data Analyst Interview Questions

1. What do Tableau's sets and groups mean?

Data is grouped using sets and groups according to predefined criteria. The primary distinction between the two is that although a set can have only two options—either in or out—a group can divide the dataset into several groups. A user should decide which group or sets to apply based on the conditions.

2.What in Excel is a macro?

An Excel macro is an algorithm or a group of steps that helps automate an operation by capturing and replaying the steps needed to finish it. Once the steps have been saved, you may construct a Macro that the user can alter and replay as often as they like.

Macro is excellent for routine work because it also gets rid of mistakes. Consider the scenario when an account manager needs to share reports about staff members who owe the company money. If so, it can be automated by utilising a macro and making small adjustments each month as necessary.


3.Gantt chart in Tableau

A Tableau Gantt chart illustrates the duration of events as well as the progression of value across the period. Along with the time axis, it has bars. The Gantt chart is primarily used as a project management tool, with each bar representing a project job.

4.In Microsoft Excel, how do you create a drop-down list?

Start by selecting the Data tab from the ribbon.
Select Data Validation from the Data Tools group.
Go to Settings > Allow > List next.
Choose the source you want to offer in the form of a list array.
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Q1: How would you handle real-time data streaming for analyzing user listening patterns?

Ans: I'd use platforms like Apache Kafka for real-time data ingestion. Using Python, I'd process this stream to identify real-time patterns and store aggregated data for further analysis.

Q2: Describe a situation where you had to use time series analysis to forecast a trend.

Ans: I analyzed monthly active users to forecast future growth. Using Python's statsmodels, I applied ARIMA modeling to the time series data and provided a forecast for the next six months.

Q3: How would you segment and analyze user behavior based on their music preferences?

Ans: I'd cluster users based on their listening history using unsupervised machine learning techniques like K-means clustering. This would help in creating personalized playlists or recommendations.

Q4: How do you handle missing or incomplete data in user listening logs?

Ans: I'd use imputation methods based on the nature of the missing data. For instance, if a user's listening time is missing, I might impute it based on their average listening time or use collaborative filtering methods to estimate it based on similar users.
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🔰 Python Toolkit for Data Analysis
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SQL Interview Questions

1. How would you find duplicate records in SQL?
2.What are various types of SQL joins?
3.What is a trigger in SQL?
4.What are different DDL,DML commands in SQL?
5.What is difference between Delete, Drop and Truncate?
6.What is difference between Union and Union all?
7.Which command give Unique values?
8. What is the difference between Where and Having Clause?
9.Give the execution of keywords in SQL?
10. What is difference between IN and BETWEEN Operator?
11. What is primary and Foreign key?
12. What is an aggregate Functions?
13. What is the difference between Rank and Dense Rank?
14. List the ACID Properties and explain what they are?
15. What is the difference between % and _ in like operator?
16. What does CTE stands for?
17. What is database?what is DBMS?What is RDMS?
18.What is Alias in SQL?
19. What is Normalisation?Describe various form?
20. How do you sort the results of a query?
21. Explain the types of Window functions?
22. What is limit and offset?
23. What is candidate key?
24. Describe various types of Alter command?
25. What is Cartesian product?

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Someone asked me today if they need to learn Python & Data Structures to become a data analyst. What's the right time to start applying for data analyst interview?

I think this is the common question which many of the other freshers might think of. So, I think it's better to answer it here for everyone's benefit.

The right time to start applying for data analyst positions depends on a few factors:

1. Skills and Experience: Ensure you have the necessary skills (e.g., SQL, Excel, Python/R, data visualization tools like Power BI or Tableau) and some relevant experience, whether through projects, internships, or previous jobs.

2. Preparation: Make sure your resume and LinkedIn profile are updated, and you have a portfolio showcasing your projects and skills. It's also important to prepare for common interview questions and case studies.

3. Job Market: Pay attention to the job market trends. Certain times of the year, like the beginning and middle of the fiscal year, might have more openings due to budget cycles.

4. Personal Readiness: Consider your current situation, including any existing commitments or obligations. You should be able to dedicate time to the job search process.

Generally, a good time to start applying is around 3-6 months before you aim to start a new job. This gives you ample time to go through the application process, which can include multiple interview rounds and potentially some waiting periods.

Also, if you know SQL & have a decent data portfolio, then you don't need to worry much on Python & Data Structures. It's good if you know these but they are not mandatory. You can still confidently apply for data analyst positions without being an expert in Python or data structures. Focus on highlighting your current skills along with hands-on projects in your resume.

Hope it helps :)
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Goldman Sachs senior data analyst interview asked questions

SQL

1 find avg of salaries department wise from table
2 Write a SQL query to see employee name and manager name using a self-join on 'employees' table with columns 'emp_id', 'name', and 'manager_id'.
3 newest joinee for every department (solved using lead lag)

POWER BI

1. What does Filter context in DAX mean?
2. Explain how to implement Row-Level Security (RLS) in Power BI.
3. Describe different types of filters in Power BI.
4. Explain the difference between 'ALL' and 'ALLSELECTED' in DAX.
5. How do you calculate the total sales for a specific product using DAX?

PYTHON

1. Create a dictionary, add elements to it, modify an element, and then print the dictionary in alphabetical order of keys.
2. Find unique values in a list of assorted numbers and print the count of how many times each value is repeated.
3. Find and print duplicate values in a list of assorted numbers, along with the number of times each value is repeated.

I have curated best 80+ top-notch Data Analytics Resources 👇👇
https://t.iss.one/DataSimplifier

Hope this helps you 😊
For a data analytics interview, focusing on key SQL topics can be crucial. Here's a list of last-minute SQL topics to revise:

1. SQL Basics:
• SELECT statements: Syntax, SELECT DISTINCT
• WHERE clause: Conditions and operators (>, <, =, LIKE, IN, BETWEEN)
• ORDER BY clause: Sorting results
• LIMIT clause: Limiting the number of rows returned

2. Joins:
• INNER JOIN
• LEFT (OUTER) JOIN
• RIGHT (OUTER) JOIN
• FULL (OUTER) JOIN
• CROSS JOIN
• Understanding join conditions and scenarios for each type of join

3. Aggregation and Grouping:
• GROUP BY clause
• HAVING clause: Filtering grouped results
• Aggregate functions: COUNT, SUM, AVG, MIN, MAX

4. Subqueries:
• Nested subqueries: Using subqueries in SELECT, FROM, WHERE, and HAVING clauses
• Correlated subqueries

5. Common Table Expressions (CTEs):
• Syntax and use cases for CTEs (WITH clause)

6. Window Functions:
• ROW_NUMBER()
• RANK()
• DENSE_RANK()
• LEAD() and LAG()
• PARTITION BY clause

7. Data Manipulation:
• INSERT, UPDATE, DELETE statements
• Understanding transaction control with COMMIT and ROLLBACK

8. Data Definition:
• CREATE TABLE
• ALTER TABLE
• DROP TABLE
• Constraints: PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL

9. Indexing:
• Purpose and types of indexes
• How indexing affects query performance

10. Performance Optimization:
• Understanding query execution plans
• Identifying and resolving common performance issues

11. SQL Functions:
• String functions: CONCAT, SUBSTRING, LENGTH
• Date functions: DATEADD, DATEDIFF, GETDATE
• Mathematical functions: ROUND, CEILING, FLOOR

12. Stored Procedures and Triggers:
• Basics of writing and using stored procedures
• Basics of writing and using triggers

13. ETL (Extract, Transform, Load):
• Understanding the process and SQL's role in ETL operations

14. Advanced Topics (if time permits):
• Understanding complex data types (JSON, XML)
• Working with large datasets and big data considerations

Hope it helps :)
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