Arcesium Senior Data Analyst Interview Questions and Answers

Q1. How SQL DB works
Ans. 
SQL DB works by storing and managing data in a structured format using tables and relationships.
• SQL DB uses tables to store data in rows and columns.

• It allows for querying data using SQL commands like SELECT, INSERT, UPDATE, DELETE.

• Relationships between tables can be established using foreign keys.

• Indexes can be used to optimize query performance.

• ACID properties ensure data integrity and consistency.
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We were provided with 3 basic data stucture questions all three were leetcode medium easy question. Total time alloted was 1hr for three questions.

2nd round was again coding round but this time question level was hard plus 10 MCQs were also given based on basic computer science knowledge.
There were 2 data structure question that was leetcode medium hard questions.

Q1. How can you prove to the client that a students with higher classes are taller than that of lower classes?
Ans. 
We can use statistical analysis to prove that students in higher classes are taller than those in lower classes.
• Collect height data of students from different classes

• Use statistical measures like mean, median, and mode to compare the heights of students in different classes

• Perform hypothesis testing to determine if the difference in height between classes is statistically significant

• Visualize the data using graphs and ...read more
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Q2. Compare two arrays in python and print if both of them are same or not?
Ans. 
Compare two arrays in python and print if both of them are same or not.
• Use the '==' operator to compare the arrays.

• If the arrays have the same elements in the same order, they are considered the same.

• If the arrays have different elements or different order, they are considered different.

• Print 'Same' if the arrays are the same, otherwise print 'Different'.
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Q3. What is permutation and combination and how is it used in data science?
Ans. 
Permutation and combination are mathematical concepts used to count the number of possible outcomes in a given scenario.
• Permutation is the arrangement of objects in a specific order while combination is the selection of objects without considering the order.

• Permutation formula: nPr = n!/(n-r)! where n is the total number of objects and r is the number of objects selected.

• Combination formula: nCr = n!/r!(n-r)! where n i...read more
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2 easy level coding questions and aptitude mcqs

Q1. 3 coding questions easy to medium level. Discussion on my project and past internship experience. Basic maths questions from probability, statistic, pnc etc..
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It was an online coding test, with 2 python questions(DP and String) and 8 MCQs.

Q1. Asked about a coding question(easy level array question) , my one of project(explain line by line), permutation and combination question.
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Q1. Same as second round.
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Though I applied for Data Analyst position through campus Recruitment Program (Kolkata). It had MCQs and Coding test, but surprisingly the MCQs were about Java, OOPs concept and basic coding questions. Hardly any ML or Analytics related like Python, SQL or BI tools related questions. As if I appeared for SDE role, not sure why it happened, but later I came to know they hired none from our college.

This did not happen, as they didn't call anyone from our college.

Easy question. Easy to clear the round

Q1. One to one technical questions based on SQL and python.
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Basic data structures, puzzles questions and statistics problems

Q1. What was your previous company project
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Q2. What are different types of indexing
Ans. 
Different types of indexing include primary indexing, secondary indexing, clustered indexing, and non-clustered indexing.
• Primary indexing: Index based on the primary key of a table, typically implemented using a B-tree structure.

• Secondary indexing: Index based on a non-primary key column, allowing for faster retrieval of data based on that column.

• Clustered indexing: Physically reorders the table based on the indexed co...read more
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Q3. How does random forest work
Ans. 
Random forest is an ensemble learning method that builds multiple decision trees and merges their predictions.
• Random forest creates a set of decision trees from randomly selected subsets of the training data.

• Each tree in the random forest independently predicts the outcome, and the final prediction is made by averaging the predictions of all the trees.

• Random forest is effective in handling high-dimensional data and can...read more
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Q4. Explain over fitting
Ans. 
Overfitting occurs when a model learns the noise in the training data rather than the underlying pattern.
• Overfitting happens when a model is too complex and captures noise in the training data.

• It leads to poor generalization to new, unseen data.

• Regularization techniques like L1/L2 regularization can help prevent overfitting.

• Cross-validation can be used to detect and prevent overfitting.

• Example: A decision tree with too...read more
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Q5. Explain macros inExcel
Ans. 
Macros in Excel are automated sequences of commands that can be created to perform repetitive tasks.
• Macros can be recorded or written using Visual Basic for Applications (VBA)

• They can automate tasks such as formatting, data manipulation, and calculations

• Macros can be assigned to buttons or keyboard shortcuts for easy access

• They can save time and reduce errors in repetitive tasks
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It was an on campus recruitment drive with questions mostly on basic statistics and algebra.

In round 2 the interviewer asked to explain one of my project and then write code for longest common substring problem.

One Simple coding problem followed with couple of probability questions and explaining the Simple Linear model in detail.