
⚡Effet Majeur⚡
Strategic consulting for critical decisions.
Since 2009, our experts in Psychology, Sociology, Economics & Innovation Strategy have been advising those who need to identify the decisive effects to act:
We defended French cultural exception (Deezer). We upended the rules of traditional hospitality (AccorHotel Jo&Joe). We got young people into sports (UCPA SportStation). We helped recycle french luxury (Dior) and brought it to the world stage (Chanel). We kept people from ending up in debt after a holiday accident (Allianz). We fueled young people's passion for home design (IKEA). We helped farmers irrigate without water loss (Telaqua). We defended the French internet (AFNIC) and domestic SMBs (EulerHermes). We helped advance women's health (Organon)...
Strategic consulting to decide under uncertainty
You face a decision that changes everything
You don't know where to start
Your advisors drown you in slides without clarity
You want to make bold calls without missing
You refuse manipulation, you seek lasting effectiveness
You need an action plan, not a report
Your team is spinning in circles, the project stalls
We are featured in the national press
Harvard Business Review, Challenges, le Figaro, 20mn talk about our achievements

AccorHotels Jo&Joe
Read the Harvard Business Review, Challenges and Le Figaro article on how we helped Marie-Suzanne Locqueneux think about the service strategy of the new AccorHotels brand

UCPA Sport Station
The interview on the construction of the new UCPA sports complexes which aim to bring sport and health back into your daily life

Epitech Digital
The article in the newspaper 20 mn where we talk about our students and how we teach them to respect users who can never be reduced to simple consumers
The Opinions of our corporate customers
All our reviews are verified by Sortlist
Allianz, personal & travel insurance
User Research & Strategic Design for the group's innovation projects
"Effet Majeur has been working on our innovation projects for almost 5 years now.
We appreciate the quality and relevance of their work and the deliverables, which always meet our expectations perfectly. In particular, the quality and depth of the strategic analyses.
Deezer, musical streaming
User Research & Strategic Design to manage the shift from family customers to Generation Z customers
"We appreciated not only the quality of the research carried out, but also the professionalism of the team and their willingness to talk to us throughout the study".
Organon, women health laboratory
User Research & Strategic Design to meet the demands of the new generation of doctors in terms of laboratory advice
"Effet Majeur has very strong expertise in both user research and strategy and they don't count the hours in producing quality deliverables."
Euler Hermes, crédit insurer
User Research & Strategic Design to find a fit to market with SME customers
"Olivier's support, in particular his ability to analyse and his vigilance in not falling back into the ways of business experts / keeping the chakras open".
Rhomberg, Swiss Jeweller
User Research & Strategic Design to continue the brand's internationalisation and connection with French customers
"The Effet Majeur agency was always ready to help us and was able to meet our deadlines thanks to a well-structured project. The mock-ups provided fully met our expectations, thanks in particular to user testing. An agency to be recommended."
En Voiture Simone, auto-écoles en lignes
User Research & Strategic Design to better meet the needs of Generation Z
"We really liked Effet Majeur's professionalism: on time, on schedule, impeccable project management, and the quality of the deliverables."
UCPA Sport Station
User Research & Strategic Design of new sports complexes in delegation
"We really appreciated the uniqueness of the work methodology based on human sciences and design. The relevance and approach of the agency's founder".
Perial investissements SCPI
User Research & Strategic Design to transform brick-and-mortar property into a relevant investment option for Generation Z
"The team's active listening and ability to take us down a path never taken by our market, while remaining true to our values."
OUR METHOD TO IDENTIFY THE DECISIVE EFFECT
1Psychology
To diagnose what's really blocking progress — the invisible power dynamics, the unspoken resistance, the deep mechanisms preventing action.
2Strategy
To move beyond superficial and cosmetic solutions, reframe the stakes at their root, identify the decisive effect that will tip the situation.
3Simulation
To test your options before committing, anticipate reactions, validate that your plan will hold against reality. You don't decide blindly.
DIAGNOSe WHAT'S REALLY BLOCKING PROGRESS
You're facing resistance you don't understand. Your project stalls despite all efforts deployed. Users don't engage. Stakeholders drag their feet for no apparent reason. The problem is never the one they present to you.
Classic diagnostics (surveys, focus groups, superficial interviews) only capture surface-level discourse. What people say is never what makes them act. It's time to call on experts — Psychologists and Sociologists — capable of revealing invisible power dynamics, unspoken resistance, the deep mechanisms that paralyze action, the work of the negative.
We use proven methods: projective tests to understand what people cannot express, what is not explicit; usage mapping tests to trace the complexity of situations and tasks; literature reviews to capitalize on all scientific knowledge; scientific experiments to identify the causes of the situations and distinguish truth from falsehood; constraint tests to grasp the dynamics of trade-offs; iconic tests to understand how graphic dimensions and communication affect decisions...
But above all: psychological modeling of change levers — identifying who influences whom, what fears block, what desires are at work and must be supported.
Usage Mapping tests
Iconic Tests
Constraints Tests
Scientific Experimentations
International user research
Through the projects carried out for our major customers, we have built up a network of partners capable of carrying out user tests all over the world. We cover key countries such as France, England, Germany, Spain, Italy, Scandinavia, the United States, Australia, Singapore and Dubai. If your project has an international stature, we can help you.
Paris, Londres, Francfort, Madrid, Rome
Test rooms, User Research, User tests
Dubai, Ryad, le Caire
Test rooms, User Research, User tests
Sydney
Test rooms, User Research, User tests
Mexico, Rio, Sao Paulo
Test rooms, User Research, User tests
A breakthrough strategy, the real thing
You are a decision-maker — CEO, Managing Director, political leader, founder. You can no longer settle for superficial analyses and generic recommendations. It is your responsibility to deeply understand the stakes and decide with clarity.
We have supported Allianz, AccorHotels, UCPA, Chanel... to rebuild their strategic approach. Our expertise: psychological modeling (identifying change levers), behavioral economics (understanding real trade-offs), economic model (validating viability), game theory (anticipating adversarial reactions), decision theory (deciding under uncertainty), risk theory (assessing what can tip), applied military strategy (defining the decisive effect and simulating your options).
The worst that can happen is to invest months in analysis and watch all your efforts collapse at the moment of execution. We help you preserve coherence between diagnosis, modeling, and action.
Don't launch projects without knowing where you're going.
Strategy
Business Model & Game Theory
Tactics
Decision Theory & Risk Theory
Engagement Mechanics
Psychological Modeling & Behavioral Economics
Design Sprints
Prototyping, Simulations & Game Design
STATISTICS TO VALIDATE YOUR HYPOTHESES
First, define the right indicators. When you understand how mechanisms work through psychological modeling, you can build strategic KPIs that truly measure what matters: your project's viability, real impact, operational effectiveness — not just conversion numbers.
Then, validate your hypotheses with rigorous statistics. You need to know if your diagnosis holds against the facts, if your options are viable, if your levers will work. Our statisticians in Human Sciences graduated from ENSAE (INSEE) and master advanced methods — qualitative and quantitative, parametric and non-parametric.
Finally, choose the right test to decide. Move beyond basic descriptive statistics that mislead you. We use: causality tests (regression, ANOVA), predictive statistics (Bayesian models, machine learning), factor analysis (PCA, CA) to reveal hidden structures, structural equation models (SEMs) to test your strategic hypotheses, segmentation analysis(clusters, typology), non-parametric tests (binomial, Chi-square goodness-of-fit, Kolmogorov-Smirnov, McNemar, Chi-square association, Spearman, Wilcoxon, Fisher exact, Cramér...). We identify critical variables, detect weak signals, validate your decisions on scientific data — not intuition.
Descriptive Statistics
Mean, Median, Standard Deviations...
Inferential Statistics
Parametric & Non-parametric
Correlation Tests & Effect Size Tests
Spearman, Cramer...
Marketing Tests
CA, PCA, Clusters...
Our Digital & Retail Expertise
Understand your users
Literature reviews
Online surveys, Barometers, Customer listening
User Research
Psychology / Sociology of uses
Projective tests & Analysis of the unspoken
Foresight
Emerging trends & Weak signals
Scientific experiments
International studies
Test logistics (panels, recruitment...)Launch new concepts
Literature reviews
Online surveys, BarNeeds & Expectations studies / Market research
Exploration of new market segments
Exploration of new product lines
Detection of competitors' opportunities & weaknesses
Narrative construction
Testing commercial & communication offers
New service design
Mockups / Prototypingometers, Customer listening
User Research
Psychology / Sociology of uses
Projective tests & Analysis of the unspoken
Foresight
Emerging trends & Weak signals
Scientific experiments
International studies
Test logistics (panels, recruitment...)Inventing new services & Innovating
Statistical data analysis (Online surveys & Data)
Research & Understanding user needs
Market usage diagnosis
Innovation strategy building
Axiomatics & Disruption axes
Engagement design
Ethical & equitable design possibilities
Mockups & Prototyping
Concept testingStrategic realignment
User needs modeling
Search for disruption axes
Users' real trade-offs
Competitive analysis & Strategic watch
Anticipation of competitors' trade-offs
Economic model & Viability analysisSupport for decision unblocking
Strategic scenario simulation
Success / failure KPI definition
Predictive models
Statistical validation of concepts
Tracking decisive effectsPrototyping & Simulations
Ergonomic audits / Existing audit
Design sprint
User personas
User journeys
Engagement mechanics
Service tree structure
Ergonomics & UX
Macro-architecture & Wireframes
Graphic design & Art Direction
User testingAgainst Nudging & Neuromarketing
Place & Importance of humans in innovation logic
Search for bright patterns for users
Innovation through Human Sciences
Effectiveness of ethical practices
Psychology & Customer listening
User Research & UX Design
Training with Les Gobelins
Training with IONIS Education Group
Incubators
User search
Scientific Research
Impact assessment
Digital Strategy
Innovation Strategy
Service Design
Game Design
Design Sprint
UX & Ergonomics
Psychology
Sociology
User research / UX research
Our latest interviews
Our latest conferences
Consumer Tests
Product Testing
Customer Reviews
Copyright © 2009 - 2026 Effet Majeur (formerly Fast & Fresh) - User research, Behavioral economy & Innovation Strategy Agency
Paris - Offices - 61 rue de Lyon, 75012 Paris



