Top Data Science Interview Questions

Due to the value of data, data science has become increasingly popular over time. Data is seen as the new oil of the future, and when correctly examined and utilized, it may be tremendously advantageous to the stakeholders. In addition to this, a data scientist has the opportunity to work in a variety of fields and solve real-world issues by utilizing cutting-edge technology. 

Data Science Interview Questions

The most popular real-time use involves quick meal delivery through apps like Uber Eats, which helps the delivery worker by displaying the shortest path from the restaurant to the destination. Moreover, item recommendation algorithms on e-commerce websites like Amazon, Flipkart, etc. use data science to suggest to users which products to purchase.

At e-commerce sites like Amazon, Flipkart, and others that employ item recommendation systems to suggest products to users based on their search history, data science is also used. Data Science is increasingly used in fraud detection applications to find any fraud engaged in credit-based financial applications, beyond only recommendation algorithms. A good data scientist is able to analyze data and use innovation and creativity to solve challenges that advance business and strategic objectives.

Q1. What exactly does the term “Data Science” mean?

Data Science is an interdisciplinary field that consists of numerous scientific methods, tools, algorithms, and machine-learning approaches that aim to identify patterns and derive practical insights from the provided raw input data through statistical and mathematical analysis.

  • The first step is to compile the pertinent data and business requirements.
  • Data cleansing, data warehousing, data staging, and data architecture are used to sustain data after it has been gathered.
  • Data exploration, mining, and analysis are tasks carried out by data processing, which can then be utilized to produce a summary of the insights obtained from the data.
  • Following the exploratory phases, the cleaned data is exposed to a variety of algorithms, depending on the needs, such as predictive analysis, regression, text mining, pattern recognition, etc.
  • The results are finally presented to the company in a visually pleasing way. This is where the aptitude for reporting, data visualization, and various business intelligence tools come into play.

Q2. How is a random forest model created?

Many different decision trees are used to create a random forest. The random forest puts all the trees together if the data is divided into many packages and a decision tree is created for each package of data.

How to construct a random forest model:

Choose ‘k’ features at random from a total of features where km

Calculate node D using the best-split point among the “k” characteristics.

Use the optimum split to divide the node into daughter nodes.

In order to complete the leaf nodes, repeat steps two and three.

Create a forest by repeating steps one through four n times to produce n trees.

Q3. How do you prevent your model from becoming overfitting?

A model that is overfitted ignores the wider picture and is only tuned for a relatively tiny quantity of data. To prevent overfitting, there are three basic strategies:

Make the model straightforward by considering fewer variables, which will help to reduce some of the noise in the training data. Use cross-validation methods, such as the k-folds method.

If you want to avoid overfitting, employ regularisation techniques like LASSO that penalize specific model parameters.

Q4. What distinguishes data science from data analytics?

Data science is the process of converting data through the use of various technical analysis techniques in order to derive insightful conclusions that a data analyst can then apply to various business settings.

Data analytics is concerned with examining the information and theories already in existence and providing the answers to queries for a more efficient and productive business-related decision-making process.

Data science fuels innovation by providing insights and solutions to issues from the future. Whereas data science focuses on predictive modeling, data analytics focuses on extracting current meaning from the historical context that already exists.

While data analytics is a more narrowly focused field, data science is a broad field that uses a variety of mathematical and scientific methods and algorithms to solve complicated issues.

Q5. Describe the circumstances that lead to both over- and underfitting.

Just the sample training set of data benefits from the model’s performance due to overfitting. The model is unable to yield any output when any fresh data is added as input. Low bias and large variation in the model are to blame for these circumstances. The likelihood of overfitting is higher for decision trees.

Underfitting: The model in this case is so basic that it is unable to recognize the correct relationship in the data, and as a result, it does not function well even with the test data. High bias and low variance are two factors that can cause this. Underfitting is a greater risk with linear regression.

Q6. What do Eigenvalues and Eigenvectors mean?

The length/magnitude of eigenvectors, which are column vectors or unit vectors, is 1. Right vectors is another name for them. In order to provide eigenvectors of varied lengths or magnitudes, eigenvalues are coefficients that are applied to the eigenvectors.

Eigendecomposition is the process of breaking down a matrix into its Eigenvectors and Eigenvalues. In order to extract useful insights from the provided matrix, these are ultimately used in machine learning techniques like PCA (Principal Component Analysis).

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Q7. When is resampling carried out?

Resampling is a technique used to sample data to increase accuracy and quantify the uncertainty of population parameters. By training the model on various dataset patterns, it is made sure that variations are taken into account. Also, it is done when doing tests on data points with different labels or when models need to be validated using random subsets.

Q8. Explain and define selection bias.

In the situation where the researcher must choose which person to study, selection bias occurs. When participants are chosen for studies in a non-random manner, there is a selection bias. The selection effect is another name for the selection bias. The sample collection process is what leads to selection bias.

Q9. These are four explanations of selection bias.

Sampling bias occurs when some individuals of a population have fewer chances than others of being included in a sample because the population is not at all random. Sampling bias is a systematic error brought on by this.

If we reach any extreme, trials may be terminated early.

Time interval: Trials may be terminated early if we hit any extreme value, however, if all variables exhibit similar invariance, the variables with the highest variance have a greater likelihood of doing so.

Data: It occurs when particular data are chosen at random and the widely accepted criteria are not followed.

The loss of participants is referred to as attrition in this context. Discounting trial participants who dropped out is what it is.

Attrition: The participants’ departure in this situation is referred to as attrition. The subjects that dropped out of the trial are discounted in this situation.

Q10. How can a non-technical person understand linear regression?

A statistical method for determining whether two variables have a linear connection is called linear regression. By “linear relationship,” we imply that when one variable rises, the other one will follow suit, and when one variable falls, the other one will follow suit as well. We develop a model that predicts future results based on a rise in one variable on the basis of this linear relationship.

Q11. When should the Classification Technique be used instead of the Regression Method?

When the result is discrete, categorical variable classification issues are typically used, however when the output is a continuous variable, regression techniques are used.

In the Regression algorithm, we try to estimate the mapping function (f) from the numerical (continuous) input variables (x) to the output variable (y).

For instance, regression trees, support vector machines (SVM), and linear regression.

We attempt to estimate the mapping function (f) from the discrete or categorical output variable (x) to the input variable (x) in the classification process (y).

For instance, decision trees, logistic regression, naive Bayes, and K nearest neighbors.

Classification and regression methods are both examples of supervised machine learning algorithms.

Q12. Why is data cleaning so important?

The process of updating or eliminating information that is inaccurate, lacking, redundant, irrelevant, or formatted wrongly is known as data cleansing, as the name suggests. The accuracy and productivity of the processes and the organization as a whole would greatly benefit from an improvement in data quality.

Data from the real world is frequently recorded in unsanitary formats. There are occasionally errors caused by a variety of factors that cause the data to be inconsistent, and occasionally only specific elements of the data. In order to prevent various systems from using the data to produce inaccurate results, data cleansing is done to separate the usable data from the raw data.

Q13. What distinguishes Data Science from big data and data analytics?

Algorithms and technologies are used in data science to extract significant and profit-generating insights from unstructured data. Data modeling, data cleaning, analysis, pre-processing, and other duties are included.

Big Data is the large collection of unprocessed, semi-processed, and structured data that is produced through a variety of methods.

And finally, operational insights into challenging business settings are provided by data analytics. Also, it aids in foreseeing potential dangers and opportunities that an organization might take advantage of.

Big data management is essentially the managing of massive amounts of data. It includes best practices for managing data and processing at a high rate while preserving data consistency. The term “data analytics” refers to the process of drawing insightful conclusions from data.

Q14. What processes are used when creating a decision tree?

Making a decision tree involves the following steps:

  • Identify the Tree’s Root Step
  • Calculate Entropy for The Classes
  • Calculate Entropy After Split for each Attribute. 
  • Do the maths for each split’s information gain.
  • Carry out the Split
  • More Splits to be done
  • Fill out the Decision Tree.

Q15. What exactly is dimension reduction? Why is it advantageous?

Dimensionality reduction is the process of transforming a large data collection into smaller data sets in order to communicate similar information more succinctly.

The main advantages of this technique are data compression and storage space reduction. Due to the smaller number of dimensions, it is also helpful in speeding up computations. Finally, it facilitates the removal of superfluous features; for example, it prevents the storage of a value in two separate units (inches and meters).

In a nutshell, dimensionality reduction is the process of acquiring a collection of major variables in order to decrease the number of random variables being taken into account. It can be split into two categories: feature extraction and feature selection.

Q16. How and how exactly may Data visualizations be used effectively?

The production of reports benefits substantially from data visualization. There are many reporting tools out there, like tableau, Qlikview, etc., which use plots, graphs, etc. to convey the big picture and results for analysis. Exploratory data analysis also makes use of data visualizations to provide an overview of the data.

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Being confident in your responses without bluffing is the key to cracking your data science interview. If you can demonstrate that you are knowledgeable about a certain technology, such as Python, R, Hadoop, Spark, or another big data technology, do so. If you are weak in a particular area, however, keep it to yourself unless specifically mentioned. It is not intended to be an exhaustive list of data scientist interview questions. And if you also want to know about Data Science with Machine Learning Interview Questions & Answers then read our previous blog.

While hiring data scientists, every organization takes a different strategy. But we do hope that the aforementioned data science technical interview questions clarify the data science interview procedure and give an insight into the kind of data scientist job interview questions asked when businesses are recruiting data. To help students learn the best method to approach the interviewer and help them with the interview, we ask industry experts and data scientists to provide their thoughts on open-ended data science interview questions as mentioned in the above section.


Describe data sciences. 

Data science is an interdisciplinary field that uses scientific methods, processes, and systems to extract knowledge from data in various forms, whether structured or unstructured or to better comprehend it.

What is the work of a data scientist?

A data scientist is a specialist who creates extremely intricate data analysis procedures through the design and development of algorithms that enable relevant information to be found in the data, results to be understood, and relevant conclusions to be drawn, providing extremely valuable knowledge for any company’s strategic decision-making.

What does a data scientist make on average in India?

The average pay for a data scientist in India is Rs. 10.5 LPA, according to Ambitionbox.

What are the major duties of a data scientist?

Improving data collection methods to create analytical systems; Processing, cleansing, and confirming the integrity of data; are some of the typical duties of a data scientist. establishing automated anomaly detection systems and monitoring their effectiveness; locating information in primary and secondary sources; employing standardized statistical procedures, performing data analysis and interpreting findings; ensuring management has access to clear data representations; building and maintaining valuable and pertinent databases and data systems; making data visualizations, graphs, and dashboards, etc.

Is data science a rewarding profession?

The fastest-growing position on LinkedIn, data science is expected to add 11.5 million jobs by 2026. It is a very lucrative career choice with employment prospects in a variety of industries and among the highest-paying positions worldwide.

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