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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

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 that your company is running a standard control and variant AB test on a feature to increase conversion rates on the landing page. The PM checks the results and finds a .04 p-value.

How would you assess the validity of the result?

Experiment Validity

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An industry leader is seeking an experienced Senior or Lead Software Engineer with a proven track record in SaaS or Digital Products, to help them deliver their platform to a traditionally corporate environment that requires disruption. Role: Senior (or Lead) Software EngineerSalary: up to £85kLocation: Guildford What you'll do:<ul><li>Lead a team of developers to design, develop, and maintain high-quality software solutions</li><li>Work with product owners and stakeholders to define requirements and deliver on time</li><li>Utilize your expertise in C#, ASP.NET Core, and Azure to build scalable and reliable applications</li><li>Mentor and guide team members to foster a culture of continuous learning and improvement</li><li>Collaborate with cross-functional teams to ensure smooth integration and deployment</li></ul> What you'll need:<ul><li>Strong proficiency in C#, ASP.NET Core, and SQL Server</li><li>Experience with cloud platforms, particularly Azure</li><li>Knowledge of JavaScript and TypeScript</li><li>Familiarity with modern web frameworks like Angular or React</li><li>Excellent problem-solving and debugging skills</li><li>Strong communication and teamwork abilities</li></ul> What they offer:<ul><li>Competitive salary and benefits package</li><li>Opportunity to work on cutting-edge technologies</li><li>Collaborative and supportive work environment</li><li>Opportunities for professional development and career growth</li></ul> Upon application for this position, you will be contacted to discuss the further details surrounding the role & company.

BI 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.

BI Engineer (Azure, Python, SQL) Location: Birmingham (4 days a week on-site)Salary: £45k - £48k Opportunity A fantastic opportunity has come up to work for a genuine market leader in an exciting and innovative industry. They plan to build a newly created BI and Data Engineering division to work alongside other Data and Analytics teams across the group. For this role, they need someone to serve as a central resource from within their Strategy and Analytics department, also working with, but not exclusive to, the Commercial, Finance, and Operational business functions, to help advance the group’s data infrastructure and support in transforming data into actionable insights and triggered events for Business Intelligence (BI) and Customer Relationship Management (CRM) system purposes. This role will be instrumental in leveraging data to ensure a fully integrated approach to data-driven decision-making and also business strategy. Day-to-day tasks <ul><li>Work across the group and with the devisions data partners to leverage all available data, building out the groups database, reporting and insights capabilities to enable data-led decision making.</li><li>Design, develop and maintain scalable, user-friendly and automated systems, data solutions and reporting that will support our analytical and business needs.</li><li>Support the insight team with visualisations, reporting and stakeholder engagement through monthly/quarterly/annual departmental reviews</li><li>Use data science/statistical modelling tools in collaboration with the analyst team and departmental stakeholders to develop Artificial Intelligence (AI) and Machine Learning (ML) functions and analytics.</li><li>Create and manage a knowledge-base, including documentation of your designs (e.g., system design, functional design, data flow design) ensuring there is version control and contingency processes for all aspects.</li></ul> Required skills and experience for the role <ul><li>Demonstrable experience or certification(s) within the field of data engineering, data science, and/or business analysis.</li><li>Practical experience of database design and data transformation, supported by ETL processing.</li><li>Managing data pipelines & orchestration that enable the transfer and processing of data. (Databricks, Microsoft Fabric, Alteryx. Snowflake, Apache)</li><li>Coding and programming, capable of working through complex problems with others from the team, adapting quickly to changing market trends and business needs. (SQL, Python or R)</li><li>Utilising cloud-based services and corresponding toolsets. (Microsoft Azure, GCP, AWS or similar).</li><li>Comfortable handling structured and unstructured data, from 1st, 2nd, and 3rd party data sources, combining multiple data sets, to produce a cohesive picture of performance and derive insights and recommendations.</li><li>Experience working directly with business stakeholders ensuring complex information is articulated in a meaningful way.</li></ul> Applying for the opportunity If you feel you have the required skills and experience and want to be considered for this opportunity, please forward an up-to-date version of your CV. If we feel your profile is a suitable match, someone will contact you within 48 hours.

Digital Waffle Interview Questions

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Digital Waffle Interview Questions

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