When I first heard about Swimply, it was described to me as “AirBnB for swimming pools.” With those four words, I had a solid idea of what Swimply does.

I was thinking more about analogies last week when I led a pitch deck workshop for startups at StartX, the accelerator for startups in the Stanford community.

One startup presented itself as “Duolingo for happiness.” Another was “Snyk for Data Governance.” We’ll discuss those comparisons below.

The “X for Y” approach is a startup pitch shortcut that contains an ounce of power and a pound of risk. Used correctly, this can be a powerful way to frame your story. I’ll also describe a related approach that is more reliably useful, and why.

Quickly, the basics. The startup “X for Y” analogy is like the Hollywood movie pitch cliché “X meets Y” (“Barbie meets The Hunger Games”) or the conceptually similar “X in Y” (“Jaws but in space”).

This shorthand can be very useful for a limited number of startups, like it was for the rash of Uber-for-X startups a decade ago. Like a rash, most of them disappeared, in part because they failed the last of the tests below:

• X should be well-known: Uber, McDonald’s, Starbucks. I’d say Duolingo is marginal and Snyk is problematic. If you have to explain it, don’t use it. At least, not as your tagline—more on that in a minute.

• X should also be well-known for something specific, and your business should mirror that thing. McDonald’s and Starbucks are similar in terms of ubiquity and consistent product—but Starbucks is higher-end and perhaps most notable for turning a $1 menu item afterthought into a $7 fetish. Tom’s Shoes (buy-one-we-gift-one) and Tindr (swipe-right/left) are other frequent examples.

• X shouldn’t have negative connotations. “Chipotle for Chinese food” would have been better before Chipotle sickened hundreds of customers.

• As you can see from the examples, this approach works best for consumer brands. “Accenture for Y” or “Salesforce for Y” requires too much explanation.

• From a business perspective, if you can crystallize your business so succinctly, the insight behind your startup may not be that insightful. Just ask Yoshi, Purple, Filld, WeFuel, and Booster Fuels, just 5 of the companies that charged into the Uber-for-Gas frenzy a decade ago (those are from a 30-second Google search; I didn’t bother to open Pitchbook to see if any are still around).

The X for Y analogy looks to quickly explain what the startup does. A more universal and powerful approach is to use a similar analogy to make a positive outcome seem more plausible. Here you’re comparing your startup to a successful firm that has already captured a ton of value from the industry you’re in. The message is that you’re just like that company, just at an earlier stage. It’s not the content, it’s the success. The not-too-subtle implication is, wouldn’t you have wanted to invest in that company’s seed round?

This works particularly well with B2B firms, and is best deployed deeper into the pitch deck, on a strategy, go-to-market, or timeline slide. I’m currently working with startups in the semiconductor, energy, medical device, and pharmaceutical industries. For all of them, finding examples of companies who had structurally comparable innovations and went on to great success is key to the pitch. These analogies offer time-travel advice to investors.

Positioning yourself as a young version of an established success is a great way to use a comparable like Snyk, which I just learned is a cybersecurity unicorn. Since you’re not using it as an explanatory template but as a future version of yourself, you can take a few seconds to explain who they are and how much they’re worth. If your audience has never heard of them, that’s almost better—they hadn’t heard of you yet, either, and suddenly they feel like everyone else is getting rich without them.

Perhaps more importantly, there’s huge internal value in finding and contemplating similarities between your startup and successful ones. Just like how writing a business plan (or creating a financial forecast) is more about scenario planning rather than accuracy, this is about establishing a best-guess benchmark that you can later use to see which assumptions were valid, which weren’t, and what missed or misunderstood.

In the case of the medical device firm, we looked at comparable companies and could see what they did. Did they immediately target insured customers or stick with self-pay ones? At what stage in their regulatory approval process did they receive the largest valuation increase? Did they license their technology or manufacture themselves?

In other words, you’re not only using the analogy to illuminate how valuable your future might be, you’re using it as a template for how you’ll get there. You’ve expanded analogies from explainers (X for Y) and time travel (we’re like X, just 5 years back) to action verbs. As this insightful HBR article puts it, you can use analogies to “apply the patterns of the past to the problems of the present.”

What unicorn are you modeling your startup after?