Technical Interview Questions (15 Questions + Answers)

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A technical interview is a type of job interview that is primarily focused on assessing your technical skills and knowledge. These interviews are common in industries like information technology, engineering, and science, where specific technical expertise is crucial for job performance.

In this article, I’m going to share common technical interview questions, especially in tech-heavy jobs. You’ll also see some sample answers so you can get a sense of how to answer each question effectively.

1) What programming languages do you know? 

Technical Interview Questions

Focus on languages that are relevant to the job or the company.

This might include Java (for Android development), Swift (for iOS development), Python (for data analysis and backend systems), and JavaScript (for web development).

Briefly indicate your level of proficiency in each language, then give examples of projects where you've used these languages. This adds credibility and shows a practical application of your skills.

Sample answer:

"I have experience with several programming languages. In Java, which I consider myself an expert, I’ve developed multiple Android applications, including a location-based service app similar to Waze. I'm also proficient in Python, which I've used for data analysis and backend development in my current role. For iOS projects, I have intermediate skills in Swift. I've used it in a couple of personal projects, including an app for real-time traffic updates. Also, I have basic knowledge of JavaScript for front-end development. Currently, I'm enhancing my JavaScript skills through an online course, as I believe in continuously updating my technical knowledge to stay relevant in the field."

This response is effective because it provides specific examples of projects and applications developed using these languages, giving credibility to the claims of proficiency.

2) What are some limitations of your favorite programming language? 

First, acknowledge the real limitations of the language without being overly critical. Explain how these limitations might impact certain types of projects or applications.

While discussing limitations, however, it's often beneficial to also mention the strengths of the language to show a well-rounded understanding.

Sample answer:

"My favorite programming language is Python. While it's excellent for rapid development and has a rich set of libraries, it does have some limitations. One significant limitation is its execution speed. Python is an interpreted language, which can make it slower than compiled languages like C++ or Java. This can be a bottleneck in high-performance computing or when processing large data sets in real time, as in traffic data processing. Another limitation is its memory consumption. Python's simplicity and flexibility come with a cost of higher memory usage compared to more efficient languages like C. That said, these issues can often be mitigated by integrating Python with other languages or using optimizations like just-in-time compilers."

The answer demonstrates a thoughtful analysis of Python. Mentioning ways to mitigate these limitations shows a problem-solving mindset, which is valuable in a technical role.

3) What design software do you know? Which do you prefer? 

Mention the design software you are familiar with. Depending on the role, this might include UI/UX design tools (like Sketch, Adobe XD, Figma), graphic design software (like Adobe Photoshop and Illustrator), or even specialized software for mapping or data visualization.

State which software you prefer and why. For this example, let’s say you’re applying for a job at Waze.

Sample answer:

"In my design work, I've gained experience with a variety of software. I frequently use Adobe Photoshop and Illustrator for graphic design tasks, such as creating icons and visual elements. For UI/UX design, I am proficient in Figma and Sketch. That said, my preferred tool is Figma due to its collaborative features and excellent UI prototyping capabilities. For instance, I recently used Figma to design and prototype a mobile app interface that required real-time collaboration with team members in different locations. This experience highlighted Figma's efficiency in a team-based environment, which I believe would be highly beneficial in Waze's collaborative and fast-paced setting. I also have some experience with GIS software, which could be relevant for working with map-based interfaces at Waze."

By providing a specific example of using Figma in a team project, the answer demonstrates practical experience and how it applies to a work setting.

4) What product management system do you like using? What’s the best one for scalability?

Start by naming a few product management systems you have experience with. This might include tools like Jira, Asana, Trello, or

Clearly state your preferred system and explain why.

Sample answer:

"In my experience, I've used several product management systems like Jira, Asana, and Trello. My personal preference is Jira, primarily for its powerful features that cater to agile project management, such as scrum and kanban boards, and its robust reporting capabilities. When considering scalability, however, I believe Asana stands out. It's incredibly user-friendly and scales well for larger teams and complex projects. For instance, in my previous role, we used Asana to manage a cross-functional project involving over 50 team members. Its flexibility in task management and the ability to integrate with various other tools made it an ideal choice for maintaining organization and clarity as the project and team grew. This scalability aspect, combined with its ease of use, makes Asana an excellent choice for dynamic environments like this company, where teams and projects are continually evolving."

The answer gives a clear preference for Jira and explains why, which demonstrates your ability to evaluate tools based on features and suitability.

5) How do you go about deploying a product? 

The goal here is to reflect an understanding of both the technical and collaborative elements involved in deploying a product. To do this, describe the steps you take in deploying a product, which might include planning, testing, staging, and production. 

Sample answer:

"In deploying a product, I follow a structured process that emphasizes collaboration and thorough testing. Initially, I focus on planning with cross-functional teams to align on the deployment objectives and timelines. For instance, in my current role, I led the deployment of a major app update, coordinating with developers, QA, and operations teams. We implemented continuous integration and continuous deployment (CI/CD) practices, which allowed us to automate much of the deployment process and ensure that each update was rigorously tested in a staging environment before going live. This approach significantly reduced deployment errors and downtime. Post-deployment, we monitored the app’s performance closely to quickly address any issues. This particular deployment was successful in enhancing user experience without any major disruptions, underlining the importance of a well-coordinated and tested deployment strategy, something I believe is critical in a dynamic environment."

The answer outlines a clear, step-by-step process, showing a methodical approach to deployment. Discussing collaboration with various teams also reflects an understanding of the importance of cross-functional teamwork in deployments.

6) What statistical methods do you prefer using?

Start by listing a few statistical methods you are familiar with and have used. This might include regression analysis, hypothesis testing, time series analysis, machine learning algorithms, etc.

Clearly state which methods you prefer and why.

Sample answer:

"In my experience as a data analyst, I've employed a variety of statistical methods depending on the nature of the data and the problem at hand. My go-to method is often regression analysis, especially for understanding relationships between variables, like how different factors influence traffic patterns. For instance, at my current job, I used multiple regression to analyze how weather conditions and time of day impact road congestion. This analysis helped in optimizing traffic flow recommendations. Another method I frequently use is time series analysis, particularly useful for forecasting. I applied this in predicting traffic trends during holiday seasons, which proved highly accurate and beneficial for planning purposes. These methods, I believe, would be particularly relevantfor analyzing and predicting traffic conditions, thereby enhancing user experience."

The answer covers different statistical methods, showing a broad skill set. It explains why certain methods are preferred, demonstrating thoughtful consideration based on experience.

7) What are the steps involved in a decision tree? 

The goal here is to show your understanding of the methodology and its practical applications. Outline the key steps in creating a decision tree, which typically include data collection and preparation, choosing a splitting criterion, growing the tree by splitting nodes, pruning the tree, and validating the model. 

Sample answer:

"In my previous role as a data analyst, I often used decision trees for classification and prediction tasks. The process starts with data collection and preparation, ensuring data quality and relevance. For example, when analyzing traffic congestion patterns, I gathered data on time, weather conditions, and event schedules. Next, I selected an appropriate splitting criterion, such as Gini impurity or information gain, to determine how to split the data at each node. In this traffic analysis, I used information gain to identify the factors most contributing to congestion. After growing the tree to a suitable depth, I pruned it to avoid overfitting, ensuring the model's generalizability. Finally, I validated the model with a separate dataset. This decision tree helped in predicting congestion levels with significant accuracy, which informed better traffic management strategies."

The answer methodically outlines the steps involved in creating a decision tree, showing a clear understanding of the process. Using terms like 'Gini impurity,' 'information gain,' and 'overfitting' demonstrates your technical proficiency.

8) How much time do you spend on unit testing? 

Describe how you balance unit testing with other development tasks. It’s important to convey that while you dedicate sufficient time to testing, you also manage time effectively to meet project deadlines.

Sample answer:

"In my development work, I consider unit testing an integral part of the process. Generally, I allocate around 30-40% of my development time to unit testing. This ensures that each component of the codebase is thoroughly tested, leading to fewer bugs and more reliable code. For instance, in a recent project where we developed a real-time traffic alert system, I spent significant time writing and refining unit tests. This was crucial for ensuring the accuracy and performance of the system, especially under varying traffic conditions. The tests not only helped catch and fix several critical bugs early but also made the codebase more maintainable and scalable. I believe this approach aligns well your company’s emphasis on reliability and performance in their app development."

The answer highlights the significance of unit testing in software development. It presents a realistic and balanced view of time management, showing that you value both quality and efficiency.

9) What type of UX framework do you prefer?

Briefly list a few UX frameworks you are familiar with. This might include Design Thinking, Lean UX, or the Google Design Sprint. Clearly state which UX framework you prefer and why.

Sample answer:

"In my UX design experience, I've worked with various frameworks, but my preferred choice is the Lean UX framework. I appreciate its focus on rapid iteration, user feedback, and a collaborative approach to design. For example, in a recent project, I applied Lean UX to redesign a mobile navigation app's interface. We started with minimal viable products, conducted quick user testing sessions, and iteratively improved the design based on real user feedback. This approach not only accelerated the design process but also ensured that the final product closely aligned with user needs and preferences. I find that Lean UX, with its emphasis on flexibility and user-centricity, is particularly effective in fast-paced and user-driven environments, where understanding and responding to user behavior is key."

The answer shows familiarity with various UX frameworks, indicating a broad understanding of the field. It explains the preference for Lean UX, focusing on aspects like rapid iteration and user feedback, which are crucial in UX design.

10) How do you determine what an end-user needs?

For this question, mention various methods you use to understand user needs, such as surveys, interviews, user testing, or analysis of usage data. Then, explain how you use data from user interactions and feedback to make informed decisions.

Sample answer:

"In my approach to understanding end-user needs, I combine direct user research with data analysis. For instance, in a previous project where we developed a ride-sharing app, I conducted user interviews to gather qualitative insights into what users valued most in such an app. We complemented this with a survey that reached a broader user base to validate our findings. Also, we analyzed user interaction data with the app's prototype to identify patterns and pain points. This multi-faceted approach helped us uncover that users were particularly concerned about safety features and ease of finding rides. As a result, we focused on enhancing these aspects in the final product. I believe this method of combining direct user feedback with data-driven insights would be particularly effective, where understanding diverse user needs is crucial for improving navigation and traffic solutions."

The answer covers various methods of understanding user needs. Mentioning the use of data analysis indicates your ability to combine qualitative insights with quantitative evidence.

11) What’s the largest data set you’ve ever worked with?

Start by specifying the size of the largest data set you've worked with. Briefly explain the project or task where you worked with this data set. This gives context to your experience.

Sample answer:

"The largest data set I've worked with was during my time at [Previous Company], where I handled a data set of approximately 500 million GPS records, amounting to about 2 terabytes of data. My role involved analyzing this data to identify patterns in urban mobility and traffic trends. To manage and process this extensive data set, I used a combination of SQL for data querying and Python for more complex analyses, including machine learning models for predictive analysis. The project required not only efficient data handling but also careful consideration of data privacy and security. This experience, I believe, aligns well with the scale and nature of data that your company works with, particularly in analyzing traffic patterns and user behavior to enhance navigation solutions."

Quantifying the data set size provides a clear understanding of the scale of data you've handled, while highlighting your specific role shows direct involvement and expertise.

12) How would you handle a data set with variables missing 25 percent of its values?  

Start by recognizing the challenge that missing data poses and its potential impact on analysis.

Then, describe the steps you would take to handle such a dataset, including data imputation, removal of missing data, or using algorithms that can handle missing values.

Sample answer:

"In dealing with datasets having a significant portion of missing values, my approach is both cautious and context-dependent. For instance, in a project where 25% of GPS location data was missing, I first assessed the pattern of missingness. Since the data was missing at random, I used multiple imputation techniques to estimate the missing values, leveraging other variables in the dataset. This approach allowed us to retain the integrity of the dataset without compromising on the size. In cases where missing data is systematic or related to critical variables, I might consider removing those records if imputation could lead to biased results. Using Python's Pandas and Scikit-Learn libraries, I've successfully managed such scenarios, ensuring that the subsequent analysis remains valid and reliable. This method of careful assessment and appropriate handling of missing data is crucial in a data-driven environment, where accurate analysis of traffic patterns is key."

This is such a great response because the example provides a real-world scenario where you’ve successfully managed missing data, adding to your credibility.

13) How do you treat outlier values?

Describe the steps you take to assess and treat outliers, such as identifying outliers using statistical methods, analyzing their causes, and deciding whether to keep, adjust, or remove them.

Sample answer:

"In my data analysis work, treating outliers is a critical step. For instance, when analyzing traffic speed data, I first used statistical methods like the IQR (Interquartile Range) to identify outliers. In one project, we noticed unusually high speeds at certain times. Instead of immediately discarding these as anomalies, I investigated further and found they coincided with emergency vehicle movements. This insight led us to adjust our analysis approach rather than removing these data points, which enriched our understanding of traffic patterns under different scenarios. This example underscores my approach to outliers: carefully assess their cause and context before deciding on their treatment. Such a method is especially relevant at this company, where nuanced understanding of traffic data is crucial for accurate navigation and traffic predictions."

The answer shows a clear understanding of the importance of outliers in data analysis. It outlines a specific and thoughtful approach to identifying and assessing outliers.

14) Tell me how you’d debug an update

When answering this question, show your systematic approach to problem-solving and your ability to handle complex software issues. Highlight how you balance being thorough with being efficient in your debugging process.

Sample answer:

"In debugging an update, my approach is methodical and data-driven. For example, in a recent project, after a major update, users reported a critical navigation error. My first step was to replicate the issue in a controlled environment. I then systematically reviewed recent code changes and utilized debugging tools to isolate the problem. I focused on the areas most affected by the update, particularly new features and modified algorithms. By analyzing the application logs, I identified a flaw in the route calculation logic introduced in the update. This issue was swiftly corrected, tested, and rolled out in a patch. My experience emphasizes the importance of a structured approach to quickly identify and resolve issues, which is essential in a dynamic, user-centric environment, where the reliability of real-time updates is crucial."

The answer outlines a structured and logical debugging process, demonstrating problem-solving skills. It also shows your ability to be both thorough and efficient, which is crucial in a fast-paced tech environment.

15) What would you change about one of your favorite products?

First, pick a product that is somewhat relevant to the company’s domain or the role you're interviewing for. This could be a tech product, a software application, or even a mobile app.

Focus on a particular feature or aspect of the product that you think could be improved, then clearly explain why you believe this change is necessary.

Sample answer:

"One of my favorite products is the Slack communication platform. While it excels in many areas, one aspect I’d change is its notification system. Currently, notifications can be overwhelming, especially in large teams or multiple channel subscriptions. To improve this, I would suggest a more intelligent, context-aware notification system. This system could learn from user behavior to prioritize notifications based on urgency and the user’s interaction patterns with different channels and team members. For example, if a user frequently interacts with certain channels or individuals, the system would prioritize these notifications. This change would enhance the user experience by reducing notification clutter, making it easier for users to focus on high-priority communications. This kind of smart, user-centric feature is also critical in apps, where delivering timely and relevant information is key to the user experience."

The answer pinpoints a specific feature - the notification system - which is a common pain point for many users. It explains why this change is needed, emphasizing user experience and productivity.

What to expect from a technical interview

The format and content of a technical interview can vary depending on the role and company, but they generally include some key elements:

Problem-Solving Questions: You may be asked to solve technical problems or puzzles to demonstrate their analytical skills and problem-solving abilities. This often involves writing code or working through technical scenarios in real time.

Technical Knowledge Assessment: Interviewers ask questions related to specific technologies, programming languages, tools, or methodologies relevant to the job. This tests your depth of knowledge in your field.

Coding Challenges: For software development roles, you might be asked to write or review code. This can be done on a whiteboard, on a computer, or as part of a take-home assignment.

System Design Questions: These questions assess your ability to design complex systems. You might be asked to design a software system, database schema, or algorithm.

Behavioral Questions: While the focus is on technical skills, some interviews also include behavioral questions to understand how you might fit into the team and company culture.

Technical Task or Project Review: Sometimes, you’re asked to discuss a past project or task they have worked on, focusing on the technical aspects and challenges they faced.

Technical interviews require preparation and practice, especially in areas like problem-solving and coding. To ace your next technical interview, prepare yourself by reviewing fundamental concepts, practicing coding problems, and doing mock interviews.

Reference this article:

Practical Psychology. (2023, December). Technical Interview Questions (15 Questions + Answers). Retrieved from

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