Prepare for and practice interview questions from Digital Waffle.

Digital Waffle Interview Questions

Digital Waffle Interview Guides

Suppose there exists a new airline named Jetco that flies domestically across North America. Jetco recently had a study commissioned that tested the boarding time of every airline, and it came out that Jetco had the fastest average boarding times of any airline.

What factors could have biased this result, and what would you look into?

What could potentially bias the average boarding time in favor of an airline that only flies domestically?

What could potentially bias the average boarding time in favor of an airline that only flies domestically?

Boarding Times Bias

A new airline came out as the fastest average boarding times compared to other airlines.  What factors could have biased this result and what would you look into?

You are testing hundreds of hypotheses with many t-tests. What considerations should be made?

What is a key disadvantage of the F-test when compared to multiple t-tests?

What is a key disadvantage of the F-test when compared to multiple t-tests?

Hundreds of Hypotheses

You are testing hundreds of hypotheses with many t-tests. What considerations should be made?

Let’s say we have a table with an <code>id</code> and <code>name</code> fields. The table holds over 100 million rows and we want to sample a random row in the table without throttling the database.

Write a query to randomly sample a row from this table.

Input:

<code>big_table</code> table

<table>
<thead>
<tr>
<th>Columns</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>id</code></td>
<td>INTEGER</td>
</tr>

<tr>
<td><code>name</code></td>
<td>VARCHAR</td>
</tr>
</tbody>
</table>

Write a query to randomly sample a row from a big table.

Random SQL Sample

Digital Waffle Salaries by Position

C# Developer£60,000 - £65,000Birmingham / Hybrid (3 days a week on-site) Tech Required for the role: SQL, C#, Web API A fantastic opportunity has come up to join a truly innovative and exciting organisation located in central Birmingham, as they look to expand their team again due to continued progression. This organisation is listed on the AIM market with an ambition for growth and success; focussed on becoming the No.1 within their professional services business in the UK (Currently 10th). They currently have over 1,450 people in their team, across 22 offices, servicing some 25,000+ clients across the full spectrum of legal and professional services. They believe that everyone has an important role to play in the success of the company, with the inclusive culture, as well as their collaborative, flexible and friendly environment, making it a great place to work.They are now seeking a talented individual to join their busy IT Team. The successful candidate will be an experienced Solutions Developer who can hit the ground running and take on a variety of projects. Main Duties:Responsibilities include, but are not limited to:Competencies:<ul><li>Responsible for the development and improvement of our Practice Management Systems</li><li>Build browser based web solutions that meet the changing needs of the business and drive efficiency as part of our ongoing automation program</li><li>Ensure that industry standards and best practices are applied across the development and database environments, leading to systems that are secure, robust and optimised</li><li>Produce and maintain documentation contributing towards the wider development infrastructure</li><li>Produce estimates (high-level and detailed) for development work</li><li>Balance work on multiple projects at one time</li><li>Integrate with third party providers by consuming API’s. This could extend building out API wrappers</li><li>Maintain databases and objects such as tables, stored procedures, views, triggers, Indexes</li><li>Handle common database procedures such as upgrade, backup, recovery, migration</li><li>Profile server resource usage, and optimise as necessary</li><li>Maintain interfaces with other systems both internal and external</li><li>Collaborate within a cross functional team to help shape technical solutions and direction</li><li>Work well with ever-changing processes to meet our company needs and requests</li></ul> Experience and Skills:<ul><li>.NET framework / .NET Core (C#)</li><li>ASP.NET MVC, Web API, Functions</li><li>Excellent understanding of Microsoft SQL Server</li><li>Expert-level T-SQL skills</li><li>Ability to write clean, efficient, readable and well documented code</li><li>Proven experience of creating and implementing effective testing plans</li><li>Experience of using code repositories</li><li>The ability to prioritise high volumes of responsibilities without delays in deliverables</li><li>Capable of troubleshooting common databases issues and debugging stored procedures</li><li>Skilled at optimising large, complicated SQL statements</li><li>Familiar with tools that can aid with profiling server resource usage and optimization</li><li>Sense of ownership and pride in your performance and its impact on company’s success</li><li>Previous experience of helping to deliver projects accurately and on time</li><li>Critical thinker and strong problem-solving skills</li><li>A proven team player, who can support others and who can adapt to changing and conflicting priorities</li><li>A confident and effective communicator who is proactive, self-motivated with a can-do attitude</li><li>Strong attention to detail and willing to expand your skill set to overcome existing challenges</li></ul> Additional Desirable Skills:<ul><li>Experience of Legal Sector</li><li>Agile development principles</li><li>Experience of using Continuous Integration</li><li>Azure Stack; Power Automate, Microsoft Power Apps</li><li>Azure DevOps pipelines</li><li>Microservice Architecture</li><li>HTML, JavaScript</li><li>KNIME</li></ul> If you feel you have the required skills and experience and are interested in the opportunity, please apply by forwarding an up-to-date version of your CV, and if we feel you meet the requirements, someone will contact you back within 24 hours.

Senior Data Scientist Location: London / Hybrid (Westminster)Salary: £80,000 - £90,000 (potentially more for the right person) A fantastic opportunity has come up to work for a truly innovative and exciting start-up that has been making waves in their industry, as they have massively expanded all areas of their teams due to their products selling millions. It doesn’t top there as they plan to create a new Data Science division within the business due to continued progression. For this role, you will have lots of opportunities to be creative and have a voice regarding how you work, and how the team develops as this will be the company's first Senior Data Scientist, who will take ownership of their powerful tracking AI technology. What is Involved<ul><li>Collaborate closely with our CPO and Head of Engineering to take charge of our groundbreaking ReflectAI® technology.</li><li>Work extensively with MediaPipe and MoveNet to leverage pose estimation coordinates provided by the libraries.</li><li>Develop rules/algorithms to accurately calculate metrics such as total reps, rep progress, rep speed and form quality by analysing the outputted coordinations.</li><li>Utilise statistical analysis techniques to minimise inaccuracies when dealing with complex occlusion scenarios.</li><li>Collaborate with our CPO to ensure technical and product requirements are understood and executed on.</li><li>Work closely with QA to resolve bugs and minimise any bugs that appear in staging/production releases.</li><li>Ensure smooth and regular release of new features including coordination and communication with Customer Support and Marketing.</li><li>Opportunity to potentially assume a leadership role as the data science team expands.</li></ul> Requirements<ul><li>Extensive experience as a data scientist within a startup / high-growth environment.</li><li>Ability to develop and implement algorithms for real-time data processing and analysis.</li><li>Strong foundation in linear algebra, geometry, and basic calculus.</li><li>Good understanding of probability and statistical analysis.</li><li>Proficiency in using JIRA or other project management tools.</li><li>Familiar with basic coding in Kotlin or Java.</li><li>Experience using MediaPipe, MoveNet or other similar machine learning models, ideally pose estimation.</li><li>Experience with feature extraction from time-series or sequential data.</li><li>Outstanding communication abilities, particularly in effectively and clearly explaining technical concepts to non-technical individuals and in writing detailed project documentation.</li><li>Meticulous and thorough in paying attention to details.</li></ul> Nice to Haves<ul><li>Experience coding in Kotlin.</li><li>Product-minded with a good understanding of how to build products.</li><li>Passion for fitness, ideally with experience building fitness products and working out.</li></ul> Applying:If you feel you have the required skills needed, and wish to be considered for this opportunity, please apply by submitting an up-to-date version of your CV, and we will contact you back with 48 hours if we feel you are a good match

Senior Software Developer£55,000 - £65,000Birmingham / Hybrid (3 days a week on-site) Tech Required for the role: SQL, C#, Web API A fantastic opportunity has come up to join a truly innovative and exciting organisation located in central Birmingham, as they look to expand their team again due to continued progression. This organisation is listed on the AIM market with an ambition for growth and success; focussed on becoming the No.1 within their professional services business in the UK (Currently 10th). They currently have over 1,450 people in their team, across 22 offices, servicing some 25,000+ clients across the full spectrum of legal and professional services. They believe that everyone has an important role to play in the success of the company, with the inclusive culture, as well as their collaborative, flexible and friendly environment, making it a great place to work.They are now seeking a talented individual to join their busy IT Team. The successful candidate will be an experienced Solutions Developer who can hit the ground running and take on a variety of projects. Main Duties:Responsibilities include, but are not limited to:Competencies:<ul><li>Responsible for the development and improvement of our Practice Management Systems</li><li>Build browser based web solutions that meet the changing needs of the business and drive efficiency as part of our ongoing automation program</li><li>Ensure that industry standards and best practices are applied across the development and database environments, leading to systems that are secure, robust and optimised</li><li>Produce and maintain documentation contributing towards the wider development infrastructure</li><li>Produce estimates (high-level and detailed) for development work</li><li>Balance work on multiple projects at one time</li><li>Integrate with third party providers by consuming API’s. This could extend building out API wrappers</li><li>Maintain databases and objects such as tables, stored procedures, views, triggers, Indexes</li><li>Handle common database procedures such as upgrade, backup, recovery, migration</li><li>Profile server resource usage, and optimise as necessary</li><li>Maintain interfaces with other systems both internal and external</li><li>Collaborate within a cross functional team to help shape technical solutions and direction</li><li>Work well with ever-changing processes to meet our company needs and requests</li></ul> Experience and Skills:<ul><li>.NET framework / .NET Core (C#)</li><li>ASP.NET MVC, Web API, Functions</li><li>Excellent understanding of Microsoft SQL Server</li><li>Expert-level T-SQL skills</li><li>Ability to write clean, efficient, readable and well documented code</li><li>Proven experience of creating and implementing effective testing plans</li><li>Experience of using code repositories</li><li>The ability to prioritise high volumes of responsibilities without delays in deliverables</li><li>Capable of troubleshooting common databases issues and debugging stored procedures</li><li>Skilled at optimising large, complicated SQL statements</li><li>Familiar with tools that can aid with profiling server resource usage and optimization</li><li>Sense of ownership and pride in your performance and its impact on company’s success</li><li>Previous experience of helping to deliver projects accurately and on time</li><li>Critical thinker and strong problem-solving skills</li><li>A proven team player, who can support others and who can adapt to changing and conflicting priorities</li><li>A confident and effective communicator who is proactive, self-motivated with a can-do attitude</li><li>Strong attention to detail and willing to expand your skill set to overcome existing challenges</li></ul> If you feel you have the required skills and experience and are interested in the opportunity, please apply by forwarding an up-to-date version of your CV, and if we feel you meet the requirements, someone will contact you back within 24 hours.

SQL Data Analyst Location: Coventry (on-site) Salary: £31,000 A rare opportunity to join a growing IT Team located in Coventry as a Business Systems Technician. In this new and exciting role, you will help support the development and delivery of diverse IT systems across the organisation. Experience working with Applications, SQL and data knowledge is essential to be successful in this opportunity as you will be involved in the management of business systems. The work that you do will have a meaningful impact on the business. You will also play a vital role in the management and administration of IT Business Systems; this includes identifying improvements, development, support, and assistance to the business. To be successful in this role our ideal person will have:<ul><li>An eye for understanding complex design (manufacturing, traceability, integration)</li><li>The drive to understand large volumes of data and system patterns.</li><li>The confidence to present your products to non-technical audiences.</li><li>The ability to adapt your communication style to account for varying levels of seniority and your audiences' requirements</li><li>Be able to define requirements, create and maintain documentation and conduct thorough testing of various systems</li></ul>We will be looking for someone who: <ul><li>Support design of test script, participating in full regression testing for the key business systems and other associated IT systems – ensuring operational impacts are identified and communicated.</li><li>Will develop knowledge of the main business systems – ERP, MES and be able to support day-today activities, including administration and basic development.</li><li>Supporting Business System division to monitor end-user system performance, report issues and maintain communications to ensure appropriate resolution.</li></ul> Essential skills & experience:<ul><li>Good IT skills</li><li>Ability to prioritise</li><li>Experience in supporting business applications</li><li>Knowledge of MS SQL Server would be advantageous</li><li>Ability to analyse data with attention to detail, identify associated trends and root cause of issues, implementing corrective action, as and when required.</li><li>Writing complex SQL queries</li><li>Ability to deploy hardware and software configuration</li><li>Proven analytical and problem solving ability</li><li>Strong written and verbal communication skills</li></ul> Applying for the opportunity: If you feel you have the required skills identified for this opportunity and wish to be considered, please forward an up-to-date version of your CV, and someone from Digital Waffle will contact you back within 48 hours if we feel you fit the criteria.

Digital Waffle is proud to have partnered with a company at the forefront of the renewable energy revolution, using artificial intelligence to optimise energy production, integration, and efficiency. We're looking for a passionate Senior Machine Learning Engineer to join our growing team and play a key role in shaping the future of sustainable energy. Responsibilities:<ul><li>Collaborate with domain experts to identify renewable energy challenges where machine learning can provide solutions.</li><li>Design, develop, and implement machine learning models for tasks such as:</li><li>Solar energy forecasting</li><li>Wind turbine performance optimization</li><li>Demand response management for the power grid</li><li>Predictive maintenance for renewable energy infrastructure</li><li>Oversee the entire machine learning lifecycle, from data acquisition and pre-processing to model deployment and monitoring.</li><li>Stay up-to-date on the latest advancements in machine learning for renewable energy applications.</li><li>Mentor and guide junior engineers on the team and lead recruitment of new team members.</li></ul> Qualifications:<ul><li>MSc/PhD in Computer Science, Engineering, Physics, or a related field (or equivalent experience).</li><li>Minimum 5 years of experience as a Machine Learning Engineer.</li><li>Strong understanding of machine learning algorithms and their applications (supervised, unsupervised, reinforcement learning).</li><li>Proven experience in designing, developing, and deploying machine learning models in production environments.</li><li>Experience working with big data and cloud platforms (AWS, Azure, GCP) is a plus.</li><li>A passion for renewable energy and sustainability.</li></ul> Benefits:<ul><li>Be part of a mission-driven company that's making a real difference in the world.</li><li>Work on challenging and impactful projects with real-world applications.</li><li>Collaborate with a talented team of engineers and scientists.</li><li>Competitive salary and benefits package.</li><li>Opportunity to learn and grow in a fast-paced environment.</li></ul>

We are proud to be supporting a company in Hamburg with a mission to harness AI to create a more sustainable, greener future. Join their vision to build innovative solutions that use artificial intelligence to tackle climate challenges and create a more sustainable future ???? The Role:As a Data Scientist on their AI Sustainability team, you'll play a crucial role in developing and deploying AI models that will significantly reduce carbon emissions. You'll work alongside a passionate team of engineers, researchers, and sustainability experts to turn complex environmental data into actionable insights. Responsibilities:<ul><li>Partner with domain experts to understand environmental challenges and translate them into data-driven problems.</li><li>Design, develop, and implement machine learning models to address sustainability issues </li><li>Clean, analyse, and interpret large and complex environmental datasets.</li><li>Communicate complex data insights effectively to technical and non-technical audiences.</li><li>Stay up-to-date on the latest advancements in AI for sustainability research and apply them to our projects.</li><li>Collaborate with the engineering team to ensure the scalability and maintainability of models in production.</li></ul> Qualifications:<ul><li>Master's degree in Computer Science, Statistics, Mathematics, or a related field (or equivalent experience).</li><li>3-5 years of experience in data science with a focus on machine learning.</li><li>Strong experience with Python and machine learning libraries (e.g., TensorFlow, PyTorch, scikit-learn).</li><li>A passion for sustainability and a desire to make a positive impact on the environment.</li></ul> If you're a talented Data Scientist who is passionate about sustainability, please apply here!

Digital Waffle is proud to have partnered with a company in Berlin, that is looking for their next Product Manager. The ideal candidate is an analytical team player who will be responsible for leading a team of high-performing individuals who own the entire product lifecycle from strategy to evaluation. You will also work cross-functionally to complete product roadmaps and discover new opportunities. Responsibilities:<ul><li>Conduct in-depth market research to identify customer needs and opportunities for AI solutions.</li><li>Collaborate with engineers, data scientists, and designers to define product vision, roadmap, and user stories.</li><li>Translate customer needs into technical requirements and user acceptance criteria.</li><li>Prioritise product features based on market demand, business goals, and technical feasibility.</li><li>Manage the product development lifecycle, including sprint planning, release planning, and go-to-market strategy.</li><li>Own the product roadmap and ensure it aligns with the company's overall strategy.</li><li>Stay up-to-date on the latest advancements in AI technology and industry trends.</li><li>Champion responsible AI practices and ensure our products are developed ethically and fairly.</li></ul> Qualifications:<ul><li>Minimum 5 years of experience in product management within the AI/Data Science sector.</li><li>Proven track record of successfully launching and managing AI products.</li><li>Strong understanding of the product development lifecycle and Agile methodologies.</li><li>Excellent analytical and problem-solving skills.</li><li>Outstanding communication and collaboration skills, with the ability to influence stakeholders across different disciplines.</li><li>A passion for AI and its potential to solve real-world problems.</li><li>Fluency in English</li></ul> Benefits:<ul><li>Competitive salary and benefits package.</li><li>Opportunity to work on cutting-edge AI technology and make a real impact.</li><li>Collaborative and fast-paced work environment.</li><li>Be part of a team of passionate and talented individuals.</li><li>Work in the heart of Berlin, a vibrant and exciting city.</li></ul>

Are you a passionate Developer, with experience leading software teams, well versed in Python, and JavaScript?If so, read below... Role: Development LeadSalary: £80-£90kLocation: Lancashire Role and Responsibilities:<ul><li>Creating exemplary code using Python</li><li>Leading a small team and supporting them with their practice.</li><li>working with Agile delivery teams to ensure a smooth process from concept to completion for each element of our digital product</li></ul> Experience:<ul><li>Python 5+ years</li><li>JavaScript 5+ years</li><li>Team Lead/Managerial roles previously held</li></ul> If you are interested, please get in touch for a more details as interviews are taking place as of next week

Job Title: Senior Software EngineerLocation: CardiffSalary: £65,000 Per Annum Digital Waffle is looking for a Senior Software Engineer to join a rapidly growing tech company in Cardiff. In this role, you'll design and develop features, write clean code, mentor team members, and collaborate across teams. You'll also take ownership of solutions and proactively manage your workload to deliver high-quality results. Key Responsibilities:<ul><li>Contribute to all stages of the product lifecycle, focusing on design and feature development</li><li>Develop clean, functional, and testable code</li><li>Enhance processes to align with business needs</li><li>Mentor and guide team members, sharing your expertise</li><li>Collaborate across teams, including Product, Support, and Infrastructure</li><li>Take ownership of solutions and manage your workload proactively</li></ul> Skillset required:<ul><li>Minimum 5 years experience in C#.NET (.NET 7+ or .NET Core)</li><li>Familiarity with software development best practices (SOLID, DRY)</li><li>Experience with RESTful APIs</li><li>Knowledge of Entity Framework, SQL, and Azure</li></ul> What’s in it for you?<ul><li>Competitive salary and performance bonuses</li><li>Exciting career advancement opportunities</li><li>Onsite perks like a free gym, secure parking, and a stocked kitchen</li><li>Collaborative team culture with strong support for learning and growth</li></ul> If you are a Senior Software Engineer interested and wish to learn more please apply or get in touch for more details. All applicant's CVs will be reviewed, and those deemed suitable will be contacted.

Digital Waffle Interview Questions

Digital Waffle Interview Guides

Digital Waffle Interview Questions

Digital Waffle Salaries by Position

Digital Waffle Opening Jobs