#validation

Measure and validate product-market fit. Indicators: 1. Sean Ellis test (% users 'very disappointed' if product disappeared >40%). 2. Retention cohorts (flattening curve after initial drop). 3. Organic growth rate (word-of-mouth, low CAC). 4. NPS score (>50 is excellent). 5. Sales cycle length (decreasing over time). 6. Customer feedback themes (solving real pain). Conduct surveys and analyze usage data. If PMF not achieved, pivot or iterate. Document assumptions and validate continuously.

Design a valid and reliable survey instrument. Steps: 1. Define constructs to measure. 2. Review existing validated scales. 3. Write clear, unbiased questions (avoid double-barreled, leading). 4. Choose appropriate response scales (Likert, semantic differential). 5. Organize logically (demographics last). 6. Pilot test with small sample (n=20-30). 7. Assess reliability (Cronbach's alpha >0.7). 8. Validate with factor analysis. Keep under 10 minutes. Use branching logic. Ensure mobile-friendly. Tools: Qualtrics, SurveyMonkey. Calculate required sample size.

Achieve and measure PMF. Indicators: 1. Sean Ellis test ('how disappointed if product went away?' >40% 'very'). 2. Organic growth and word-of-mouth. 3. High retention rates. 4. Users getting core value quickly. 5. Revenue growth acceleration. 6. Qualitative: strong customer enthusiasm. Before PMF: talk to users constantly, iterate quickly. After PMF: scale efficiently. Don't scale prematurely. PMF is not permanent - can lose it.

Create a Lean Canvas for rapid business planning. Nine sections: 1. Problem (top 3 customer problems). 2. Customer Segments (target users). 3. Unique Value Proposition (single clear message). 4. Solution (top 3 features). 5. Channels (path to customers). 6. Revenue Streams (pricing model). 7. Cost Structure (key costs). 8. Key Metrics (measurable success). 9. Unfair Advantage (competitive moat). Fill out in 20 minutes. Iterate based on customer feedback. Use as living document for startup validation.

Create a regular expression to validate a strong password. The password must be at least 8 characters long, contain at least one uppercase letter, one lowercase letter, one number, and one special character (e.g., !, @, #, $). Explain the different parts of the regex.

Build reactive forms using Angular 17 signals. Implementation: 1. Signal-based form state management. 2. Computed validation rules with effect(). 3. Custom validators with async signals. 4. Real-time error messages. 5. Dirty/touched state tracking. 6. Form submission with loading states. 7. Field dependencies and conditional validation. 8. Accessibility with ARIA attributes. Use standalone components and inject FormBuilder. Display inline errors with smooth animations.

Build an automated data quality monitoring system. Checks to implement: 1. Completeness (null percentage per column). 2. Uniqueness (duplicate detection). 3. Validity (regex patterns, range checks). 4. Timeliness (data freshness alerts). 5. Consistency (cross-table referential integrity). Create a dashboard showing quality scores over time with alerting for threshold breaches. Use Great Expectations or custom Python validators.

Create reliable and valid survey instruments. Design process: 1. Literature review to identify existing validated scales. 2. Define constructs clearly, create item pool (3-5 items per construct). 3. Expert review panel (5-7 subject matter experts) for content validity. 4. Pilot testing with 30-50 participants for clarity and comprehension. 5. Main validation study (minimum 10 participants per item, 200+ total). Analysis: 1. Exploratory Factor Analysis (EFA) to identify factor structure. 2. Confirmatory Factor Analysis (CFA) to test model fit (CFI > 0.95, RMSEA < 0.08). 3. Internal consistency reliability (Cronbach's α > 0.70). 4. Test-retest reliability over 2-week period (r > 0.80). 5. Discriminant and convergent validity testing. Use software: R lavaan, SPSS, or Mplus.

Validate with lean startup methodology. Process: 1. Define riskiest assumption. 2. Create minimum viable product. 3. Build-Measure-Learn loop. 4. Customer interviews for insights. 5. Quantitative metrics tracking. 6. Pivot or persevere decisions. 7. Iterate rapidly. 8. Validated learning over vanity metrics. Start with landing page or prototype. Test willingness to pay early. Fail fast and cheap.