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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 you work for a social media company that has just done a launch in a new city. Looking at weekly metrics, you see a slow decrease in the average number of comments per user from January to March in this city.

The company has been consistently growing new users in the city from January to March.

What are some reasons why the average number of comments per user would be decreasing and what metrics would you look into?

What metric could be used to measure if active users are still engaging on the platform despite an overall decrease in the average number of comments per user?

What metric could be used to measure if active users are still engaging on the platform despite an overall decrease in the average number of comments per user?

Decreasing Comments

How would you investigate a decline in the average number of comments per user?

Harrington Starr Salaries by Position

Senior Quantitative Analyst – London (Hybrid) My client is looking to expand their Quantitative Modelling Team and is looking for talented individuals with a passion for sports and mathematics. With partnerships across the USA, UK, and Europe, this is a unique opportunity to shape the future of their technical platforms, including sportsbook, lottery, casino, and financial trading solutions. Key Responsibilities:<ul><li>Design and implement advanced predictive models for sports betting markets.</li><li>Develop and refine algorithms and tools to optimise trading performance.</li><li>Interpret and analyse large, complex data sets to drive strategic decisions.</li><li>Collaborate with multidisciplinary teams to enhance and innovate technical solutions.</li></ul> Essential Skills:<ul><li>Expertise in programming with R or Python.</li><li>MSc in Statistics, Mathematics, Data Science, or a related discipline.</li><li>3+ years of experience in sports betting, gambling, or a strong track record of academic research (PhD is a plus).</li><li>In-depth knowledge of predictive modeling and statistical techniques.</li></ul> Desirable Skills:<ul><li>Knowledge of state-space models, Bayesian inference, machine learning.</li><li>Experience with Julia, C++, Java, or TensorFlow.</li></ul> Benefits:<ul><li>Competitive salary, pension matching up to 7%, discretionary bonus, 25 days holiday.</li><li>High-end workspace in Shoreditch, hybrid working flexibility.</li></ul> If interested, please contact lucia.paolinelli@harringtonstarr for information or apply directly to this advert.

Sports Quant Analyst – Prop Trading FirmLocation: LondonCompensation: Competitive base salary + Bonus My client, a boutique prop trading firm with a specialised focus on sports trading, is expanding their London-based team. They're seeking an experienced Quant Analyst to develop and refine trading strategies across sports markets, particularly in cricket, tennis, football, and horse racing. Role Overview:As a Quant Analyst, you'll leverage your quantitative skills and programming expertise to analyse large datasets and uncover profitable trading insights. You’ll work closely with data analysts and developers in a collaborative, flat structure environment equipped with the latest technology. Requirements:<ul><li>MSc or higher in a quantitative field (Statistics, Mathematics, Data Science, etc.).</li><li>PhD preferred</li><li>3+ years as a quant in a financial or sports trading environment.</li><li>Proficiency in Python, MATLAB, R, C#, or C++.</li><li>Strong statistical and analytical skills with a proven track record in sports trading.</li></ul> Benefits:<ul><li>Competitive pay with performance-based bonus.</li><li>Growth opportunities and a dynamic office culture.</li><li>Benefits like gym membership, team outings, and a strong work-life balance.</li></ul> We ask that only candidates with proven experience as a quant or sports analyst apply for this position. Applications without this background will not be considered. Thank you for your understanding. To apply, please send your CV to Lucia.paolinelli@harringtonstarr.com.

Senior Full Stack Software Engineer - C# / React£90,000 - £130,000 basic + bonus Company SnapshotJoin a finance sector powerhouse making waves globally. With a track record of award-winning tech solutions spanning various industries, this company leads innovation in finance for over 30 years. Now's your chance to be part of their expansion and groundbreaking tech deliveries. Perks Highlights<ul><li>Fully funded certifications and subscriptions.</li><li>Comprehensive health and insurance coverage.</li><li>Robust pension plan with scaling benefits.</li><li>Generous holidays, with extra time off for charity work.</li><li>Hybrid work setup at our central London office.</li><li>Competitive bonuses.</li><li>Salary: £90,000 - £130,000, experience-dependent.</li></ul> Your Role<ul><li>Craft the path for modern web apps.</li><li>Drive innovation in cutting-edge projects, coding and testing components.</li><li>Collaborate with a dynamic team to shape architecture and deliver top-tier solutions.</li><li>Engage with business users to translate needs into robust systems.</li><li>Uphold integrity and company values while pushing your career forward.</li></ul> Your Skills<ul><li>Proficient in C# and .Net.</li><li>Familiarity with JavaScript, TypeScript, React, NodeJS, Docker.</li><li>Strong communication skills and a thirst for learning.</li><li>TDD knowledge.</li><li>Cloud experience, ideally AWS.</li><li>UK work eligibility without sponsorship.</li></ul> Let's ConnectFor more details or to explore similar roles, contact Con Lam at Harrington Starr - 07360 532134. Click apply or connect via LinkedIn for a confidential chat.

Business Analyst - Merger & Acquisition project£700 Per day Inside IR35London-based client - Hybrid working (3 days a week in office) You'll be working for a leading Financial Services company who have an extended history of high performance and strong cash flow that results in them acquiring multiple companies into their Global portfolio per year You'll be joining as a Business Analyst to aid the Merger and Acquisition process of newly acquired business. Working with the business to understand where entity rationalisation can be beneficial. Skills required:<ul><li>Strong Business Analysis skills</li><li>Financial Services knowledge of financial trading instruments - Multi-asset class knowledge preferred. (cash and derivatives: OTC and exchange-traded, IR, FI, Commodities, Equities)</li><li>Must have Regulation & Compliance Knowledge - implementing regulations project experience for multiple regulations e.g., MiFID II, IFPR, SM&CR</li><li>Prior Experience of post-merger integration or entity rationalisation projects</li></ul> Apply to Barry.Ansell@HarringtonStarr.com or click the APPLY button. *Not all applications will get a personalised response.

Data Scientist | Exchange Firm in London |£60,000 - £80,000 base + Bonus | Hybrid We have a fantastic opportunity for a Data Scientist to work side by side with one of our clients Quant Researchers in their London office. Forming part of the research team you will help manage the structuring of liquidity for some of the most sophisticated trading participants in financial markets. You will be responsible for activity monitoring, analysing market microstructure and researching trading activity. You will push forward their capability, understanding and effectiveness to deliver more for their clients. With data from trading, liquidity and risk, you will support and drive the research and decision making. What will you be doing? <ul><li>Support the research and application of initiatives across trading, liquidity and risk</li><li>Manage and expand the analytical tool suite to automate analysis and improve monitoring of daily trading activity</li><li>Independently deliver analysis for both ad-hoc and large scale requirements</li><li>Identify patterns and behaviours that are indicative of future performance and employ advanced statistical modelling to utilise them</li><li>Work with the sales and liquidity team to understand their clients and their needs</li><li>Support the research development team in understanding and implementing data and trading improvements to their internal systems</li></ul> What are we looking for? <ul><li>Bachelor's degree or equivalent experience (Statistics, Mathematics, Computer Science, Engineering, etc.)</li><li>At least 1 - 2 years' of experience.</li><li>Fluency in a programming language (Python, C,C++, Java, SQL)</li></ul> My client are keen to have this candidate signed before the end of October so don't hesitate to apply or get in touch at sean.kennedy@harringtonstarr.com

Data Analyst | Systematic Sports Trading Firm in London | £50,000 - £70,000 + Bonus Excited to launch a Data Analyst search for a world renowned Systematic Sports Trading firm. Our client is an established player in the space, boasting a state of the art office in Central London. Due to further expansion, they are looking for a talented Data Analyst to come and join their team and play a pivotal part in their large scale growth for 2025. What are we looking for?<ul><li>Prior experience working within Sports Trading/Betting would be advantageous but candidates with a strong interest within this area are also interesting.</li><li>1-2 years minimum hands on Data Analyst experience ideally within a financial services environment.</li><li>Experience with SQL, Visualization Tools (Power Bi/Tableau/Looker) & Python.</li><li>Able to extract and clean data, before putting into reports.</li><li>Able to work 5days a week onsite in the Central London HQ.</li><li>Bachelor’s degree or higher in Computer Science, Mathematics, EE or other computational discipline from a top tier university.</li></ul> Please apply today or get in touch with me for more information at sean.kennedy@harringtonstarr.com

Software Engineer - C# & ReactTrading and Analytics - Risk Management Central London – Office based. Hybrid - Salary: Up to £120,000+ Benefits + BonusC#, .NET Core, My SQL, Kafka, JavaScript, React, Redux, AWS, Kubernetes, Docker Harrington Starr has partnered with an innovative Technology focussed Hedge Fund that specialise in developing unique software systems for the financial sector are seeking a Full Stack C# and React UI Developer. This is an exciting opportunity to join a small team within small but highly dynamic Tech Team that will be working on a Portfolio Trading Application for the Head Trader. You will be working on the Front Office Trading desk working on performance related development using the .NET Stack. We are looking for an experienced Full Stack Engineer with C# .NET core on the backend with React and JavaScript on the UI. You will have a degree in computer science from a reputable University and have a good understanding of C#, .NET Core, JavaScript and React. The main Portfolio applications are used by the main Trader & Analytics Team to define the main trading decision across the Equities Market. You will be building out functionality for User Interfaces and performance based applications with the Microsoft Stack and JavaScript React front end including AWS cloud based services and Microservices. Key requirements within this opportunity are as follows:<ul><li>Extensive knowledge of Equities Trading and Trading Lifecycle</li><li>Knowledge of an Front Office Environment and a Front Office Trading Desk.</li><li>Experience in working with Traders and Quants.</li><li>Experience with C# .Net and .NET Core</li><li>Solid experience with JavaScript and React Framework</li><li>Experience with NodeJS</li><li>Extensive experience with CI/CD</li><li>Experience with AWS Cloud</li><li>Experience with Kubernetes and Docker.</li><li>A 2:1 or above in Computer Science - Required</li></ul>A leader within their community and a specialise Development team already in place, due to recent success they are looking to further build out their Software Engineering team in their London Office. You will be working on cutting edge platforms for Trading and analytics for Financial and Sports trading software. If you feel you are ready to take the next step of your career then please apply via Link.

Software Engineer - Python#techforgood The company This is an unmissable opportunity to join a scaling Fintech who are helping financial firms impact the environment in a positive way. They are building the tools and technology to allow investors to invest sustainably. If you are interested in joining a start up who are changing the world then this could be a fit for you. We are looking for a Software engineer to join their London office. What you will get <ul><li>Access to continuous learning and personal growth.</li><li>Wellbeing and health insurance for you and your family.</li><li>Excellent benefits.</li><li>Fully funded certifications </li><li>£60,000 - £70,000 basic depending on experience. </li><li>Equity opportunities. </li><li>Regular pay reviews. </li><li>Remote working with occasional travel to London office. </li></ul> What you will do <ul><li>Back end Python development and work with large datasets.</li><li>Greenfield development projects while enhancing existing tools. </li><li>Be responsible for the design and implementation. </li><li>Build cutting edge software that is being used by 1000s of users worldwide. </li><li>Work on a modern technology stack. </li><li>Collaborate with multi-disciplinary teams. </li></ul> What you need:<ul><li>Strong experience in Python.</li><li>Background in working with SQL and Data analytics. </li><li>Building services that are designed for scale. </li><li>Strong communication skills.</li><li>Worked with Docker or similar. </li><li>An interest in upskilling and learning new technologies.</li></ul> Find out moreIf you would like to have a confidential conversation and find out more about this opportunity, then get in touch with Con Lam at Harrington Starr -07367 446935 or click on the apply button below.

C#.NET, Full Stack Development, JavaScript, Angular, RESTfulAPI, Azure, MicroservicesLondon – Hybrid Perm Role £50000 - £80000Harrington Starr has partnered with an innovative Technology focused Hedge Fund that are looking to hire .NET Full Stack Developers using .NET Core on the backend and JavaScript Angular on the Front end.Working on a Front office trading applications platform that is used by both internal and external users – this technology focussed client is now looking at the next gen tech for enhancements and performance.What you will need:<ul><li>A strong background in Full Stack .NET and JavaScript Angular.</li><li>Hands on development with Angular Framework.</li><li>A strong understanding of SQL Server.</li><li>Microservices Architecture experience.</li><li>Strong knowledge of RESTful API’s and JSON.</li><li>Any cloud tech using Azure and it related tech.</li><li>2:1 or above in Computer Science or related subject.</li><li>Be willing to work on-site fully from their London office.</li><li>Right to work in the UK indefinitely without sponsorship.</li></ul> If you would like to book in a confidential phone call to discuss this opportunity in further detail, please apply below or send through a copy of your up-to-date CV via the apply link. This is a great opportunity to work with a forward thinking Technology focussed hedge fund where you will be working with a small but highly dynamic team and working on complex software engineering projects.Apply below!

Data Engineer | Wealth Management Firm | £60,000 - £70,000 + Bonus Brand new Data Engineer hire for an established Wealth Management firm in the UK who are expanding their data team in a new office in Bristol. You will be joining a collaborative team of 6 and working closely with their experienced Head of Data to support upcoming projects to improve and update their existing data lake and data pipelines, utilising cloud-native data warehousing and ETL tools. This will be a hybrid role requiring 2/3 days in the office and suit a candidate with mid-senior level experience. You do not have to come from a prior financial services background for this role but a keen interest within this domain would be desirable. What are we looking for?<ul><li>Strong experience across the SQL stack including SSRS, SSIS etc.</li><li>Minimum of 3-4 years hands on Data Engineering experience.</li><li>Familiarity with Data Lake architectures and Cloud Services (ideally Azure)</li><li>Background in the design and implementation of ETL processes to integrate data from multiple sources into a cohesive data warehouse environment.</li><li>Keen interest in Financial Services.</li><li>Ability to work collaboratively and take ownership over projects.</li></ul> My client are looking to move quick on this so please apply today or get in touch with me for more information at sean.kennedy@harringtonstarr.com

Harrington Starr Interview Questions

Harrington Starr Interview Guides

Harrington Starr Interview Questions

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