Blinkit Senior Data Analyst Interview Questions and Answers

Given time series data of provider, compute hour wise provider wise no of seconds online

Q1. Case study on the customer churn.
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Q2. Questions on Probability and CLT
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Q1. What are assumptions in Linear Regression
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Assumptions in Linear Regression
• Linear relationship between independent and dependent variables

• Homoscedasticity (constant variance) of residuals

• Independence of residuals

• Normal distribution of residuals

• No multicollinearity among independent variables
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Q2. What are overfitting and underfitting
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Overfitting and underfitting are two common problems in machine learning models.
• Overfitting occurs when a model is too complex and fits the training data too closely, resulting in poor performance on new data.

• Underfitting occurs when a model is too simple and cannot capture the underlying patterns in the data, resulting in poor performance on both training and new data.

• Overfitting can be prevented by using regularizati...read more
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Q3. How do you improve the performance of Linear Regression
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To improve the performance of Linear Regression, you can consider feature engineering, regularization, and handling outliers.
• Perform feature engineering to create new features that capture important information.

• Apply regularization techniques like L1 or L2 regularization to prevent overfitting.

• Handle outliers by either removing them or using robust regression techniques.

• Check for multicollinearity among the independent...read more
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Q4. What are the metrics used to evaluate Linear Regression
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Metrics used to evaluate Linear Regression
• Mean Squared Error (MSE)

• Root Mean Squared Error (RMSE)

• R-squared (R²)

• Adjusted R-squared (Adj R²)

• Mean Absolute Error (MAE)

• Residual Sum of Squares (RSS)

• Akaike Information Criterion (AIC)

• Bayesian Information Criterion (BIC)
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Q5. What is Cost function and Error Function
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Cost function measures the difference between predicted and actual values. Error function measures the average of cost function.
• Cost function is used to evaluate the performance of a machine learning model.

• It measures the difference between predicted and actual values.

• Error function is the average of cost function over the entire dataset.

• It is used to optimize the parameters of the model.

• Examples of cost functions are ...read more
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Q6. How do you handle Overfitting in Linear Regression
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Overfitting in Linear Regression can be handled by using regularization techniques.
• Regularization techniques like Ridge regression and Lasso regression can help in reducing overfitting.

• Cross-validation can be used to find the optimal regularization parameter.

• Feature selection and dimensionality reduction techniques can also help in reducing overfitting.

• Collecting more data can help in reducing overfitting by providing
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Q7. What is the difference between Least Squares Method and the maximum likelihood
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Least Squares Method and Maximum Likelihood are both used to estimate parameters, but differ in their approach.
• Least Squares Method minimizes the sum of squared errors between the observed and predicted values.

• Maximum Likelihood estimates the parameters that maximize the likelihood of observing the given data.

• Least Squares Method assumes that the errors are normally distributed and independent.

• Maximum Likelihood does n...read more
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Q8. What is the formula of Logistic Regression
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Logistic Regression formula is used to model the probability of a certain event occurring.
• The formula is: P(Y=1) = e^(b0 + b1*X1 + b2*X2 + ... + bn*Xn) / (1 + e^(b0 + b1*X1 + b2*X2 + ... + bn*Xn))

• Y is the dependent variable and X1, X2, ..., Xn are the independent variables

• b0, b1, b2, ..., bn are the coefficients that need to be estimated

• The formula is used to predict the probability of a binary outcome, such as whether...read more
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Q9. What is Type I and Type II error
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Type I error is rejecting a true null hypothesis, while Type II error is failing to reject a false null hypothesis.
• Type I error is also known as a false positive

• Type II error is also known as a false negative

• Type I error occurs when the significance level is set too high

• Type II error occurs when the significance level is set too low

• Examples: Type I error - Convicting an innocent person, Type II error - Failing to convi...read more
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Q10. What metrics do you use to evaluate classification models
Ans. 
Metrics used to evaluate classification models
• Accuracy

• Precision

• Recall

• F1 Score

• ROC Curve

• Confusion Matrix
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Q11. How do you handle overfitting and underfitting in Decision Trees
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Overfitting in decision trees can be handled by pruning, reducing tree depth, increasing dataset size, and using ensemble methods.
• Prune the tree to remove unnecessary branches

• Reduce tree depth to prevent overfitting

• Increase dataset size to improve model generalization

• Use ensemble methods like Random Forest to reduce overfitting

• Underfitting can be handled by increasing tree depth, adding more features, and reducing regu...read more
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Case Study - How do you improve user engagement of Facebook?
Guesstimates - How many people watched the Squid Game series on Netflix

How do you reduce partner churn in UC?

Sql based questions on hackerrank.

Q1. Why Swiggy? Where do you see yourself in 5 years?
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Q1. Can you describe your current project or any past projects that are related to machine learning?
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Q2. What is Linnear regression ?
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Q3. Diff betn linnear and logistic regression?
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Q4. Diff betn random forest vs decision tree algorithm?
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Q5. Formula for precision?
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Q6. Common metrics to find accuracy of linnear regression model and Logistic regression model?
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Q7. What is recall and F1?
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Q8. Tell me example of ensemble technique?
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Questions from arrays and strings and some aptitude questions

Q1. How to merge 2 csv files
Ans. 
To merge two CSV files, you can use software like Microsoft Excel or programming languages like Python.
• Open both CSV files in a software like Microsoft Excel.

• Copy the data from one CSV file and paste it into the other CSV file.

• Save the merged CSV file with a new name.

• Alternatively, you can use programming languages like Python to merge CSV files by reading both files, combining the data, and writing to a new file.
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Q2. Basic questions on arrays
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Q1. 3 reasons why u choose this company
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I applied to this company because of its reputation in the industry, opportunities for growth, and company culture.
• Reputation in the industry - I have heard great things about the company's innovative projects and successful track record.

• Opportunities for growth - The company offers various training programs and career advancement opportunities for employees.

• Company culture - I value a positive work environment and the...read more
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Q1. Questions on python
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Q1. Basic Excel Questions
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Q2. Medium and Basic SQL Questions
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Q3. Resume based Question
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Q4. Case Study Questions
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Q5. Questions on Project
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SQL based questions wer asked on joins , rank function,