Data Sciences Challenges
Explore data science challenges on Ewance to build skills employers expect from analysts and ML engineers. Work through challenges on data cleaning, exploratory analysis, modeling, and storytelling with data.
Most Popular
- AnalysisBeginnerNew
Model Bogotá's Bike-Share Network as a Graph for Overnight Rebalancing
Using only the supplied station directory, the aggregated origin-to-destination trip table, and the operations brief, build a directed weighted graph where each station is a nod…
- Graphs
- Networkx
- Shortest Path
Open coursework - CodeIntermediateNew
Design a Lock-Free Concurrent Queue for an Event Bus
Implement an MPSC (multi-producer single-consumer) ring-buffer queue in Go using atomic operations only — no mutexes. Prove correctness with the Go race detector across 8 produc…
- Concurrent Data Structures
- Lock Free Programming
- Go
Data Structures - CodeIntermediateNew
Index a Reference Genome with a Suffix Array in Rust
Using the reference-genome FASTA in the provided materials, build an in-memory suffix array (DC3 or SA-IS construction) over the 4-letter DNA alphabet in Rust, then implement co…
- Suffix Arrays
- String Algorithms
- Rust
Open coursework - DesignBeginnerNew
Redesign an Executive Revenue Dashboard for an E-Commerce Marketplace
Interview the CFO, the head of category, and 2 finance analysts for 30 minutes each to elicit the 6 analytic tasks the dashboard must support (e.g. month-over-month variance, ca…
- Dashboard Design
- Visual Encoding
- Task Analysis
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- DesignIntermediateNew
Design an Interactive Subway On-Time Performance Visualization
Using the provided arrival-performance sample dataset, design a small-multiples layout — one compact panel per subway line — that uses a horizon-chart encoding to show on-time p…
- D3
- Webgl
- Interactive Visualization
Open coursework - ResearchIntermediateNew
Recommend a Color Scale for a Flood-Risk Map With Evidence
Working only from the provided materials, reach and defend a single recommendation. Read the decision file (decision-file) to understand the actors, the prior complaint, and the…
- Perceptual Study
- Color Scales
- Experimental Design
Open coursework - DesignIntermediateNew
Author a Scrollytelling Story on a Three-Week Ad-Fraud Anomaly
Using the internal investigation report (provided) and the anomaly dataset (provided), design a seven-section scrollytelling narrative and build it as a static web page. Structu…
- Narrative Visualization
- Scrollytelling
- Svelte
Open coursework - CodeIntermediateNew
Build a WCAG 2.2 AA Accessible Chart Component Library
Build a React and TypeScript component library that exports four chart components (bar, line, scatter, heatmap), each rendering the figures in the provided sample analytics data…
- Accessibility
- Wcag 2
- React
Open coursework - Browse challenges
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Pricing Strategist
Set the price that captures value without leaving sales on the table. Demand modelling, willingness-to-pay research, and the disciplined experimentation that turns pricing into a competitive advantage.
- DesignFoundationalNew
Redesign a Vet-Clinic SaaS Database to Third Normal Form
Using the current schema dump and the eight most-common reporting queries provided to you, design a replacement database structure for VetLedger. First, produce an entity-relati…
- Data Modeling
- Normalization
- SQL
Open coursework - AnalysisBeginnerNew
Index a Slow 90-Million-Row FinTech Reporting Database
Your analysis task is to read the engineering ticket and the six reporting queries in the case file (M1), study the transactions table definition, column statistics, and write w…
- Indexing
- Query Optimization
- Explain Analyze
Open coursework - DesignIntermediateNew
Resolve the Quota Double-Spend: Design Meterly's Order-Provisioning Schema
Working only from the materials provided, reach and defend a database design. Read the de-identified incident record (incident-file) and the business-rules brief (requirements-b…
- Transactions
- Acid
- Isolation Levels
Open coursework - AnalysisBeginnerNew
Plan and Validate a MySQL-to-PostgreSQL Records Migration
Using the de-identified case record (incident-file-records-office), the representative schema export (mysql-schema-sample), and the anonymized staging extract (staging-records-s…
- Database Migration
- Mysql
- Postgresql
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- DesignBeginnerNew
Choose a Sidecar Cache Store for a Hotel-Search API
Using the captured workload trace and the platform requirements brief in the provided materials, design a proposal that selects one of Redis, KeyDB, or DragonflyDB as the sideca…
- Nosql
- Redis
- Benchmarking
Open coursework - AnalysisSeniorNew
Diagnose and Fix Query-Planner Misestimates in a FinTech Warehouse
For each of the 6 queries, capture EXPLAIN (ANALYZE, BUFFERS) and compare estimated vs actual rows at each node. Identify the misestimate source per query (single-column stats s…
- Query Optimization
- Postgresql Planner
- Extended Statistics
Advanced Database Systems - DesignSeniorNew
Design a Strongly-Consistent Distributed Counter for API Quotas
Using the requirements brief ('quotaguard-requirements-brief'), the workload-and-cost reference sheet ('quotaguard-workload-cost-sheet'), and the failure-scenario worksheet ('qu…
- Distributed Databases
- Consensus
- Strong Consistency
Open coursework - CodeIntermediateNew
Tame Lock Contention on a Shared Property-Manager CRM Database
Working only from the four provided materials, produce a fix-and-prove package. Start with the recorded lock snapshots (lock_snapshots) and the environment case file (db_environ…
- Concurrency Control
- Lock Contention
- Postgresql
Open coursework - ResearchSeniorNew
Compare NewSQL Architectures for a Real-Time Inventory Platform
Working only from the materials provided — the de-identified evaluation file (case_file_inventory_eval), the contentious-transactions specification (transactions_spec), and the …
- Newsql
- Distributed Databases
- Raft
Open coursework - CodeBeginnerNew
Ship a Production CI/CD Pipeline for a Fitness-Studio CRM Startup
Using the FlexDesk starter service and Dockerfile, the current-deploy case file, and the pipeline requirements spec provided, build a complete continuous integration and continu…
- Ci Cd
- Github Actions
- Container Signing
Open coursework - DesignIntermediateNew
Design a Zero-Downtime Multi-Region PostgreSQL Migration for an EdTech Platform
Using the infrastructure inventory (infra-inventory), the database schema sample (schema-subset), the workload metrics (workload-metrics), and the service-level brief (sla-brief…
- Blue Green Deployment
- Logical Replication
- Postgresql
Open coursework - DesignBeginnerNew
Design a Verified UART Receiver and Loopback for an FPGA Sensor Hub
Propose and deliver a UART receiver for Helax's sensor hub that meets the functional requirements in the requirements brief (the 'uart-requirements-brief' material): 16-times ov…
- Verilog
- Uart
- Fpga
Open coursework - CodeSeniorNew
Implement a Pipelined RISC-V (RV32I) Core for Automotive Telemetry
Implement a classic 5-stage RV32I pipeline in SystemVerilog. Include data-forwarding from EX/MEM and MEM/WB back to EX, a load-use stall, and branch resolution in EX with a 1-cy…
- Systemverilog
- Risc V
- Pipelining
Digital Systems Design - DesignIntermediateNew
Rescue a 3x3 Convolution Accelerator on Zynq UltraScale+
Working only from the materials provided, reach and defend an engineering judgment, then deliver the working accelerator that proves it. Read the engineering case file ('vision-…
- Systemverilog
- Fpga
- Axi Stream
Open coursework - AnalysisIntermediateNew
Tune Database Consistency for a Ride-Hailing Match Engine
Working only from the materials provided, analyse why the matching glitch appears under load and argue for a consistency policy per query class. Start from the cluster topology …
- Consistency Models
- Cassandra
- Distributed Tracing
Open coursework - DesignIntermediateNew
Migrate a 6TB Social-Commerce Database to a Sharded Topology
Using the supplied schema specification and the seven-day anonymized query-workload export, decide the correct shard key for each table and justify it from observed access patte…
- Database Sharding
- Postgresql
- Vitess
Open coursework
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