Mom Test & JTBD
The Mom Test vs Jobs-to-be-Done: same discipline, different lenses
TL;DR
The Mom Test and Jobs-to-be-Done aren't rival methods you pick between. They work at different levels. The Mom Test is question discipline: ask about past behavior, talk about the last real project, never put the answer inside the question, and treat a compliment as noise. Jobs-to-be-Done is motivation archaeology: find the job a person hired a product to do, the forces of progress that moved them, and the switch moment when they changed solutions. Both refuse the same thing, the hypothetical. The Mom Test governs how you ask; JTBD governs what you're digging for. Run them together: a switch interview held to Mom Test rules is the strongest qualitative move you have.
The one thing both refuse: hypotheticals
Start with what these two methods agree on, because it's the part most interviews get wrong.
Neither one trusts a prediction. Ask someone "would you use a tool that did X" and you get a guess dressed up as data. People are generous, they want to be helpful, and they're bad at forecasting their own behavior. So both methods walk you off the hypothetical and onto the record of what actually happened.
The Mom Test puts it as a rule about the question: talk about specifics in the past, not opinions about the future. Jobs-to-be-Done puts it as a rule about the target: reconstruct a real decision a person already made, not a scenario they might face. Same instinct, two doors into it. A compliment is not data, and neither is a confident guess about next quarter.
If you keep one idea from this piece, keep that. Everything below is two disciplined ways of staying on the side of things that happened.
The Mom Test: question discipline
The Mom Test is Rob Fitzpatrick's set of rules for talking to customers without lying to yourself. The name comes from a simple test: ask your mom about your business idea and she'll tell you it's wonderful, because she loves you. A good question survives even a biased person. A bad one collects flattery.
The discipline lives at the level of the individual question. Three rules carry most of the weight:
- Ask about past behavior, not opinions. "When did you last run into this?" beats "Do you think this is a problem?"
- Anchor on the last real project, not a hypothetical. "Walk me through the last time you did this" beats "How do you usually handle this?" The word usually invites a tidy story that never happened.
- Never put the answer inside the question. A leading question plants its own answer and harvests agreement. The respondent nods, and you learn nothing.
The Mom Test also names the data that looks like signal but isn't. Fitzpatrick calls out three bad-data types: compliments ("that's a great idea"), hypothetical fluff ("I would definitely use that"), and wishlists ("you should add a feature for X"). All three feel encouraging. None of them tell you what a person will do, because none of them describe what a person did.
What the Mom Test does not do is tell you what to be curious about. It's a filter, not a map. It keeps a conversation honest. It won't, on its own, point you at the decision that matters. That's the other lens.
Jobs-to-be-Done: the forces of progress and the switch interview
Jobs-to-be-Done, developed by Clayton Christensen and Bob Moesta, starts from a different question: not "who is this customer" but "what progress were they trying to make." People don't buy products; they hire them to do a job in a particular situation. Find the job and you understand the demand. Christensen's milkshake study is the canonical example: commuters "hired" a morning milkshake to make a boring drive less dull and keep them full until lunch, a job no demographic profile would ever reveal.
JTBD digs at the level of motivation, and it gives you a structure to dig with. The four forces of progress explain why a person does or doesn't switch:
- Push of the current situation (what's frustrating about how they cope today).
- Pull of the new solution (what draws them toward something better).
- Habit of the present (the comfort of the status quo, even when it's bad).
- Anxiety about the new (the fear of change and the unknown).
Push and pull drive the switch. Habit and anxiety hold it back. Progress happens when the first pair outweighs the second.
The tool for surfacing all four is the switch interview: a timeline walkthrough of the moment a customer changed solutions. You don't ask what they want. You reconstruct the days around the switch in order. When did they first realize the old way wasn't working? What did they do next? When did money actually leave their account, and what happened that day? Practitioner guides from teams like dscout and User Interviews lay out the same move under different names, and the reason it works is the reason the Mom Test works: it anchors on an event the person genuinely lived through, not a forecast.
So JTBD tells you where to dig. It just doesn't enforce how you ask once you're down there, which is exactly the gap the Mom Test fills.
Where they overlap and where they differ
Here's the comparison side by side.
| The Mom Test | Jobs-to-be-Done | |
|---|---|---|
| What it governs | How you ask each question | What you're digging for |
| Level | The individual question | The customer's motivation |
| Core unit | A non-leading question about past behavior | The job, the forces, the switch moment |
| Origin | Rob Fitzpatrick, The Mom Test | Christensen and Moesta |
| Signature move | Treat compliments, fluff, and wishlists as noise | The switch interview timeline |
| Refuses | Hypotheticals, leading questions, flattery | Hypotheticals, demographics-as-explanation |
| Failure it prevents | Collecting flattery that feels like validation | Building for a customer you've misread |
| Blind spot alone | Won't tell you what to be curious about | Won't stop you from leading the witness |
The overlap is the spine: both demand past behavior, both throw out the hypothetical, both distrust the confident opinion. The difference is altitude. The Mom Test is a microscope on the question. JTBD is a map of the motivation. You can ask a flawless Mom Test question about the wrong thing, and you can have a brilliant JTBD hypothesis and ruin it by leading the witness in the first follow-up. Each method covers the other's blind spot.
Running both in one interview
In practice you don't choose. You stack them.
Let JTBD set the agenda. Walk into the conversation hunting for a job, the forces around it, and a real switch. That's your map; it decides which territory is worth the time.
Then let the Mom Test govern every question you ask along the way. When the person hands you a compliment, log it as noise and ask what they actually did. When you reach a thin answer, resist the urge to paraphrase it back, because paraphrasing leads them. Probe instead: "what happened right before that?" Follow the flinch, the small hesitation worth chasing, not the script.
The two combine like this. JTBD: "Take me back to the day you decided your old process wasn't working." Mom Test guarding the follow-ups so you never feed the answer, never accept a guess, never reward flattery. Map plus discipline. You end up with a reconstructed decision, the forces that drove it, and verbatims you can trust, because every question that produced them held the line.
This is the standard Lùc is built around. The hard part isn't knowing the rules; it's holding both lenses at once across dozens of interviews without drifting, which is exactly where tired humans and rushed projects start to slip. We enforce the question discipline and the motivation structure together, on every conversation, so the data stays honest at volume. Discipline is the product.
Frequently asked questions
What's the difference between the Mom Test and Jobs-to-be-Done interviews?
The Mom Test is a set of rules for how you ask: talk about past behavior and the last real project, never plant the answer inside the question, and treat compliments as noise. Jobs-to-be-Done is a model for what you dig for: the job a person hired a product to do, the forces that pushed and pulled them, and the moment they changed solutions. One governs the question. The other governs the goal. They don't compete.
Should I use the Mom Test or Jobs-to-be-Done?
Use both. They operate at different levels, so the choice is a false one. The Mom Test keeps each question honest so your data is real. JTBD tells you which real things to chase. A switch interview run with Mom Test discipline is stronger than either method on its own. If you're deciding how many of those interviews to run, that's a separate question with a researched answer: see how many customer interviews are enough.
What is a JTBD switch interview?
A switch interview is a Jobs-to-be-Done timeline walkthrough of the moment a customer changed solutions. Instead of asking what someone wants, you reconstruct the days around the switch in order: when the old way started failing, what they did next, and what happened on the day money actually changed hands. Done well, it surfaces all four forces of progress, the push, the pull, the habit, and the anxiety. It works because it anchors on a real event the person lived through, not a prediction about the future.
Lùc runs Mom Test- and JTBD-disciplined interviews at volume, so your team spends its hours on synthesis instead of running the same conversation forty times. Join the closed beta.