Practice
Methods, decision models and practical guides
Methodology and decision models are part of the theoretical framework:
— Theory IndexPractical Guides
Smartphone Buying Guide
A Selection Logic guide to choosing a phone by needs, evidence, reversibility, and security policy—not hype.
How to Build Objective Evaluation Criteria
A practical method for defining measurable, repeatable criteria and preventing hidden value assumptions.
A General Product Evaluation Dimension System
A reusable evaluation dimension framework: structure first, weights come from your needs.
Dietary Supplements Buying Guide
Evidence-first supplement selection under high information asymmetry and marketing pressure.
Bottled Water Buying Guide
A low-friction guide for a low-stakes category: safe, fit-for-purpose water without marketing myths.
AI Smart Glasses Buying Guide
A Selection Logic guide to choosing AI smart glasses by needs, evidence, and reversibility—not marketing hype.
Air Conditioner Buying Guide
Choose an air conditioner by needs and evidence—avoid cooling capacity (tonnage) miscalculation, efficiency label misuse, and cooling/heating confusion. A Selection Logic guide.
Air Fryer Buying Guide
How to choose an air fryer by capacity, oven replacement vs supplement, and feature claims—without marketing hype. A Selection Logic guide.
Air Purifier Buying Guide
Choose an air purifier by needs and evidence—avoid CADR/HEPA grade confusion and exaggerated room-size claims. A Selection Logic guide.
Backpack Buying Guide
How to choose a backpack or commuter bag by real capacity, carry system, and waterproofing—not marketing specs. A Selection Logic systematic guide.
Bicycle Buying Guide
How to choose a bicycle: frame material, drivetrain level, city vs. sport use. A Selection Logic guide.
Blood Pressure Monitor Buying Guide
How to choose a blood pressure monitor by electronic vs mercury, wrist vs arm accuracy, and certification—without marketing hype. A Selection Logic guide.
Bluetooth Speaker Buying Guide
How to choose a Bluetooth speaker by needs and evidence—avoid unreferenced frequency/power numbers and IP-rating myths. A Selection Logic guide.
Camera Buying Guide
Choose a camera and lenses by needs and evidence—avoid megapixel myth, phone-vs-camera confusion, and lens-system lock-in. A Selection Logic guide.
Cat Litter Buying Guide
How to choose cat litter by odor control, clump speed, and chemical safety—not marketing claims. A Selection Logic guide.
Child Car Seat Buying Guide
How to choose a child car seat: certification (R44 vs R129), age/weight/height groups, vehicle fit. A Selection Logic guide.
Coffee Beans Buying Guide
How to choose coffee beans: roast level, origin claims, and freshness. A Selection Logic guide.
Coffee Machine Buying Guide
How to choose a coffee machine: match full-auto, semi-auto, capsule, or pour-over to your needs. A Selection Logic guide.
Contact Lens Buying Guide
How to choose contact lenses by daily vs monthly cost, water content, and parameters—without marketing hype. A Selection Logic guide.
Cookware Buying Guide
How to choose cookware: stainless, cast iron, nonstick—when to use which, and coating safety. A Selection Logic guide.
Cross-Border Shopping Guide
How to choose and is it worth it? Use the Selection Logic framework to assess duty, shipping, warranty, and channel trust for rational cross-border buying.
Dash Cam Buying Guide
How to choose a dash cam: resolution/frame rate hype vs. reality, night vision claims. A Selection Logic guide.
Desktop PC Buying Guide
Choose a desktop PC by needs and evidence—avoid prebuilt vs DIY confusion and GPU tier-list misuse. A Selection Logic guide.
Diaper Buying Guide
How to choose diapers by absorption claims, breathability tests, and domestic vs. import trade-offs—not marketing numbers. A Selection Logic guide.
Dishwasher Buying Guide
How to choose a dishwasher by place-setting capacity, built-in vs countertop, and water use—without marketing hype. A Selection Logic guide.
Down Jacket Buying Guide
How to choose a down jacket by fill weight, fill power, and temperature rating—not brand prestige or duck vs. goose marketing. A Selection Logic guide.
E-book Reader Buying Guide
Choose an e-book reader by needs and evidence—avoid ecosystem lock-in and resolution/display tech confusion. A Selection Logic guide.
Electric Razor Buying Guide
How to choose an electric razor by foil vs rotary fit and blade head claims—without marketing hype. A Selection Logic guide.
Electric Scooter Buying Guide
How to choose an electric scooter: range claims vs. reality, IP waterproofing, brake systems. A Selection Logic guide.
Electric Toothbrush Buying Guide
How to choose an electric toothbrush by vibration and modes—and replacement head cost—without marketing hype. A Selection Logic guide.
Ergonomic Chair Buying Guide
Choose an ergonomic chair by needs and evidence—avoid lumbar range, material/breathability, and certification hype. A Selection Logic guide.
Eyeglasses Buying Guide
How to choose eyeglasses by index, coating, and online vs in-store—without marketing hype. A Selection Logic guide.
Glucose Meter Buying Guide
How to choose a glucose meter: accuracy standards, consumables cost lock-in, and CGM vs fingerstick. A Selection Logic guide.
Hair Dryer Buying Guide
How to choose a hair dryer by wattage, ion/feature claims, and brand premium—without marketing hype. A Selection Logic guide.
Humidifier Buying Guide
How to choose a humidifier or dehumidifier by mist type, coverage area, and noise—without marketing hype. A Selection Logic guide.
How to Avoid Impulse Buying
How to avoid impulse purchases? Use the Selection Logic framework to recognize instant gratification, scarcity, and anchoring—and build rational buying habits.
Infant Formula Buying Guide
How to choose infant formula by stage, ingredient key metrics, and regulatory compliance—not stage marketing. A Selection Logic guide.
Kitchen Knife Buying Guide
How to choose kitchen knives: steel grades, HRC hardness, and Western vs Asian needs. A Selection Logic guide.
Laptop Buying Guide
How to choose a laptop by needs and evidence—avoid core-count myths, RAM/storage confusion, and inflated battery claims. A Selection Logic guide.
Learning Tablet Buying Guide
How to choose a kids' learning tablet by eye-care claims, content quality, and hardware—not specs. A Selection Logic guide.
Luggage Buying Guide
How to choose luggage: PC, ABS, aluminum—real differences, capacity vs. dimensions, and airline limits. A Selection Logic guide.
Massage Gun Buying Guide
How to choose a massage gun by stroke/torque claims, noise, and use contraindications—without marketing hype. A Selection Logic guide.
Mattress Buying Guide
How to choose a mattress: spring-count hype, firmness and body type, certifications. A Selection Logic guide.
Monitor Buying Guide
Choose a monitor by needs and evidence—avoid color gamut/accuracy/refresh confusion and eye-care certification hype. A Selection Logic guide.
Olive Oil Buying Guide
How to choose olive oil: extra virgin standards, origin vs quality, and adulteration. A Selection Logic guide.
Perfume Buying Guide
How to choose perfume by concentration, longevity claims, and online buying risks—without marketing hype. A Selection Logic guide.
Pet Food Buying Guide
How to choose cat or dog food by ingredient list order, protein source, and dry vs. wet trade-offs—not marketing claims. A Selection Logic guide.
Pillow Buying Guide
How to choose a pillow by sleep position, fill material, and loft—not marketing claims. A Selection Logic systematic guide.
Power Bank Buying Guide
Choose a power bank by needs and evidence—avoid capacity inflation (mAh vs Wh) and fast-charge protocol compatibility traps. A Selection Logic guide.
How to Compare Prices
How to do price comparison? Use the Selection Logic framework: same-spec comparison, time cost, and cognitive budget so you compare rationally.
Printer Buying Guide
Choose a printer by needs and evidence—avoid machine vs consumables traps and continuous vs OEM cost miscalculation. A Selection Logic guide.
Projector Buying Guide
Choose a projector by needs and evidence—avoid ANSI vs claimed lumens fraud and inflated contrast claims. A Selection Logic guide.
Protein Powder Buying Guide
How to choose protein powder by protein content calculation, adulteration and certification, and need assessment—without marketing hype. A Selection Logic guide.
How to Evaluate Product Reviews
How to tell if a review is trustworthy? This guide uses the Selection Logic framework—source credibility, conflict of interest, and cross-checking—to build a rational review filter.
Red Wine Buying Guide
How to choose red wine: avoid vintage/variety talk, score-system hype, and price deception. A Selection Logic guide.
Refrigerator Buying Guide
Choose a refrigerator by needs and evidence—avoid volume calculation errors, compartment-need mismatch, and energy label misuse. A Selection Logic guide.
Refurbished Products Buying Guide
How to choose refurbished and is it reliable? Use the Selection Logic framework to tell official from third-party refurb, warranty, and reversibility.
Rice Cooker Buying Guide
How to choose a rice cooker or pressure cooker: IH vs conventional heating, when pressure is needed. A Selection Logic guide.
Robot Vacuum Buying Guide
How to choose a robot vacuum by suction (Pa), mapping, and edge cleaning—without marketing hype. A Selection Logic guide.
WiFi Router Buying Guide
Choose a WiFi router by needs and evidence—avoid WiFi 6/6E/7 hype, theoretical vs real speeds, and exaggerated wall-penetration claims. A Selection Logic guide.
Running Shoes Buying Guide
How to choose running shoes by needs, not foot-type hype or support vs cushion marketing. A Selection Logic guide.
Second-Hand Buying Guide
How to choose and avoid pitfalls when buying second-hand? Use the Selection Logic framework to assess information asymmetry, condition, and channel trust.
Security Camera Buying Guide
How to choose a home security camera by actual night vision quality, storage costs, and privacy trade-offs—not megapixel numbers. A Selection Logic guide.
Skincare Buying Guide
How to choose skincare by ingredients, efficacy claims, and skin type—without ingredient hype or overclaim. A Selection Logic guide.
Smart Fitness Equipment Buying Guide
How to choose smart fitness equipment: subscription traps and hardware–content lock-in. A Selection Logic guide.
Smart Lock Buying Guide
How to choose a smart lock by cylinder security grade and whether you need connectivity—without marketing hype. A Selection Logic guide.
Smartwatch Buying Guide
How to choose a smartwatch by needs and evidence—avoid inflated health-accuracy claims and ecosystem lock-in. A Selection Logic guide.
Sneakers Buying Guide
How to choose sneakers or everyday shoes: limited-edition hype vs. practical value, sizing systems. A Selection Logic guide.
Sofa Buying Guide
How to choose a sofa by foam density, frame quality, and long-term fabric maintenance—not showroom appearance. A Selection Logic systematic guide.
Stroller Buying Guide
How to choose a stroller by push feel, suspension, folded size, and frame safety—not marketing claims. A Selection Logic guide.
How to Evaluate Subscriptions
Is a subscription worth it? Use the Selection Logic framework to assess cost per use, usage frequency, and exit cost for rational subscription decisions.
Sunscreen Buying Guide
How to choose sunscreen by SPF vs PA, physical vs chemical—without marketing hype. A Selection Logic guide.
Tablet Buying Guide
How to choose a tablet by needs—clarify boundaries vs phone/laptop and avoid accessory traps. A Selection Logic guide.
Tea Buying Guide
How to choose tea: avoid grade-labeling games, origin claims, and storage traps. A Selection Logic guide.
Treadmill Buying Guide
How to choose a treadmill by motor power claims, incline value, and home vs commercial—without marketing hype. A Selection Logic guide.
TV Buying Guide
Choose a TV by needs and evidence—avoid 8K hype, panel-type confusion, and claimed vs peak brightness. A Selection Logic guide.
How to Evaluate Warranty
Is extended warranty worth it? Use the Selection Logic framework to assess coverage, failure rates, and usage horizon for rational warranty decisions.
Washing Machine Buying Guide
How to choose a washing machine by drum vs impeller fit, capacity, and wash programs—without marketing hype. A Selection Logic guide.
Water Heater Buying Guide
How to choose a water heater by electric vs gas, tank vs tankless, and power/capacity—without marketing hype. A Selection Logic guide.
Water Purifier Buying Guide
Choose a water purifier by needs and evidence—avoid RO vs ultrafiltration confusion, TDS pen misuse, and wastewater ratio traps. A Selection Logic guide.
Wireless Earphones Buying Guide
How to choose wireless earphones by needs and evidence—avoid frequency-response number games and inflated noise-cancelling claims. A Selection Logic guide.
Yoga Mat Buying Guide
How to choose a yoga mat by needs: TPE vs NBR vs natural rubber, thickness, and grip. A Selection Logic guide.