Hindustan Times - Dhruvon Technology Hindustan Times - Dhruvon Technology

Top Data Science Interview Questions and Answers | Data Scientist

Data science is a rapidly growing field, and with its increasing popularity, the competition for data science positions has become more intense. As the leading provider of Data Science Certification Online, we understand- to stand out from the crowd and secure your dream job in data science, it is essential to prepare for the most commonly asked interview questions. In this blog post, we will explore some of the top data science interview questions for freshers and provide you with valuable insights and tips to help you succeed.

Top Data Science Interview Questions and Answers | Data Scientist

1. What is Data Science?

Data Science is a multidisciplinary field that combines various techniques, tools, and methodologies to extract insights and knowledge from data sets. It involves the process of collecting, data cleaning, data analysis, and interpreting large and complex data sets to uncover patterns, trends, and actionable information. Data Science utilizes a combination of statistical analysis, machine learning algorithms, and domain expertise to gain valuable insights and make data-driven decisions. It is a powerful discipline that has applications in various industries, including finance, healthcare, marketing, and technology, among others.

This question serves as an icebreaker and allows the interviewer to gauge your understanding of the field. It is important to provide a concise yet comprehensive definition of data science, highlighting its role in extracting meaningful insights from data to drive decision-making. Do you want to prepare for a Data Science career on an advanced level? Enroll on Dhruvon's Data Science Certification Online soon!

2. What is the difference between supervised and unsupervised learning?

The main difference between supervised and unsupervised learning lies in the presence or absence of labelled data during the training process.

Supervised learning is a type of machine learning where the model is trained on labelled data. Labeled data means that each input has a corresponding output or target value. The goal of supervised learning is to learn a mapping function that can accurately predict the output for new, unseen inputs. It requires a training phase where the model learns from the labelled data and a testing phase to evaluate its performance on unseen data.

On the other hand, unsupervised learning deals with unlabeled data. In this type of learning, the model is tasked with finding patterns, structures, or relationships within the data without any explicit guidance or labels. The goal is to discover hidden patterns or group similar data points together based on their inherent similarities. Unsupervised learning algorithms explore the data to identify clusters, anomalies, or latent factors without prior knowledge of the expected output.

In summary, supervised learning requires labelled data for training and focuses on predicting specific outputs, while unsupervised learning works with unlabeled data to discover hidden patterns or structures within the data.

3. What is regularization, and why is it important?

Regularization is a technique used in machine learning to prevent overfitting and improve the generalization ability of models. It involves adding a penalty term to the loss function during training, which discourages large weights or complex models. Regularization helps to control model complexity, reduce the impact of noisy or irrelevant features, and make the model more robust. By avoiding overfitting, regularization improves the model's ability to generalize well on unseen data and enhances its overall performance.

Pro-Tip: Discuss the importance of regularization in improving model generalization and controlling model complexity. Join Dhruvon's. Online Data Science and Machine Learning Program to prepare for interviews while you learn data science from industry experts.

4. Explain the difference between classification and regression.

Classification and regression are two fundamental tasks in machine learning. Classification involves predicting discrete, categorical labels or classes for an input. It aims to classify data into predefined categories or classes based on features and patterns. Examples include email spam detection or image classification.

In contrast, regression predicts continuous, numerical values as outputs. It aims to estimate or approximate a real-valued output based on input variables. Examples include predicting housing prices or stock market forecasts. While classification deals with categorical outputs, regression focuses on numerical outputs, making them distinct tasks in machine learning.

5. How would you handle missing data in a dataset?

Handling missing data in a dataset requires careful consideration. One approach is to remove the rows or columns with missing data, but this may result in the loss of valuable information. Another option is to impute the missing values using techniques such as mean, median, mode, or regression imputation. Alternatively, advanced methods like multiple imputation or machine learning algorithms can be used to predict missing values. The choice of approach depends on the nature and amount of missing data, as well as the specific requirements of the analysis.

6. How would you tackle an imbalanced dataset?

Handling an imbalanced dataset requires special attention to ensure fair and accurate predictions. One approach is to collect more data for minority classes. If that's not possible, resampling techniques like oversampling the minority class or undersampling the majority class can be employed. Another option is to use algorithms specifically designed for imbalanced data, such as cost-sensitive learning or ensemble methods like SMOTE (Synthetic Minority Over-sampling Technique). Additionally, performance metrics like precision, recall, and F1 score should be considered instead of accuracy to evaluate model performance accurately. Our Data Science Certification Online is designed to prepare you to handle such dataset challenges hands-on!

7. How to build a random forest model?

To build a random forest model, start by selecting a dataset with a target variable and multiple predictor variables. Randomly split the dataset into a training set and a test set. Then, create multiple decision trees using subsets of the training data, randomly selecting predictor variables for each tree. Each tree is trained using a bootstrap sampling technique. The final prediction is made by aggregating the predictions of all the trees in the forest. The model's performance can be evaluated using metrics such as accuracy, precision, recall, or F1 score on the test set.


Data science interviews can be daunting, but with proper preparation and understanding of the most commonly asked questions, you can increase your chances of success. It is crucial to stay updated with the latest trends and techniques in data science to showcase your expertise during interviews. If you are looking for a comprehensive data science program that covers all the essential topics and provides hands-on experience, consider Dhruvon's Online Data Science and Machine Learning Program. With a team of experienced instructors and a practical approach to learning, this program equips you with the skills needed to excel in the field of data science.

Remember, practice makes perfect, so make sure to reinforce your knowledge by working on real-world projects and participating in coding challenges. Best of luck in your data science journey!