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Last week, I wrote about how impressed I was with Duolingo’s new feature and how they were able to convince me to pay a premium subscription. You can read a little more about it here. This week, as I was drawing and listening to Podcasts, I stumbled across this gem (you can listen to this here):


I have been a Duolingo power user for 3 years now. My longest streak on Duolingo is 345 days (till this very day, I am still impressed by myself with that ;) ). I never paid a dime during that time.

But that changed in Duolingo’s March update for me. I paid 60 bucks for the whole year. Even I was fascinated with how quickly I was compelled to pay. So here, i want to break down how that happened a bit more here. At the core of this simple attempt is ‘monetization’.

Disclaimer: I call it March update because…


I use Pinterest for collecting inspirations. Over the years, I have really come to love Pinterest’s recommendations on the home page and the pin board. It is very impressive. I came across a great in-depth video about Pinterest’s feed ranking engine. (A little funny that I came across this video from YouTube recommendation. I tried searching previously but most of the results are mostly about SEO-ing pinterest’s recommendation).

Here I try my best to record all the interesting things from the video.

Here’s the original video:

The talk can be broken up into the following sections:

  1. Forming an engaging…


John Egan from Pinterest has done a series of very fascinating talks about email and notifications. This blog is an attempt to organize and learn from one of his talks on scaling email operation at Pinterest. This is a great case study on how ML plays an instrumental role in providing value and driving engagement for the end users.

Email & Notifications at Pinterest

At the start: Emails and notifications weren’t really taken seriously at Pinterest.

Today: Emails and notificaitons are responsible for 20% of the company’s daily active users (DAUs)

How John Egan turned emails and notifications became a core growth drivers for Pinterest.


I still vividly remember Peter Thiel’s advice for Startups in his “Zero to One”.

“Competition is bad. Be a monopoly in a small market.” (Not verbatim, obviously)

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That thought somehow seem related to two other stories I want to share here.

The first one was a story of the two men who went hunting in the forest. It is widely known that men can’t run faster than bears and the only effective to survive in front of them is to play dead. During one of these two men’s hunting trips, suddenly, a bear came out of nowhere. The two guy…


Context and why this matters

Previously, I wrote about the simple questions to ask in talking to a user. Its simplicity is great but further contexts can be helpful. Also, that series questions are going in really deep around the problems the user has (i.e why he has the problem, how often, attempted solutions etc.). That series of questions are really good for getting more details but just asking problem itself isn’t enough. There should be a structure in how to operationalize these problem interviews. For example, how do these individual problem interviews fit together in the process of validating a market.

From a clarification…


Every company is a funnel. Every step of that funnel is an intense match between forces that will decide on how many move forward and how many drop off. That ratio is conversion.

Internet is full of people who can say more interesting things about this but here I am here to help you but mostly myself remember the simple questions to ask around improving conversion.

(Drum roll for the YC videos. This week is brought to you by Kevin Hale on conversion rate. Focusing on landing page)

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Remember These:

  1. Benchmarks of conversion: Shareware (0.5%), Casual Download Game (2%), Freemium SaaS(1.5% —…


Previously, I wrote about business models based on the video produced by Andreesen Horowitz here. While that was a great way of thinking about typical types of business models but I recently found an even more structured way of looking at business models as opposed to a listicle. That’s from Croll & Yoskovitz’s lean Analytics book.

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Shifting perspective on things help doesn’t it? Credit to this amazing illustrator: https://dribbble.com/merooseth

The book is a big proponent of the ability to simply describe businesses models. If you cannot describe it in a simple sentence then either it typically doesn’t work or you yourself don’t have clarity on this.

Croll & Yoskovitz analyzes business models by…


In the previous post, founder of SuperHuman briefly mentioned HXC as a key component of them finding product market fit. In this post, I want to go deeper into the concept of HXC and see how that relates to the process of building true product market fit.

Julie Supan, the branding head of Youtube, Airbnb, Dropbox and Thumbtack, shared her perspective over positioning through the lens of HXC in her interview with firstround capitcal here.

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HXC Overview

HXC is key to positioning and to find true positioning (good positioning is important to focus and avoiding confusion), here are the recommended 5 questions…


If you are like me (who follows A16z, YC, Greylock, FirstRound Capital and the rest of the startup community fervently), you’d probably come across the term “product/market fit” more frequently than you’d like.

Just like what Dan Olsen (Author of “The Lean Product Playbook”) said, the phrase has been treated as a binary post-hoc evaluation of an startup. xxx failed because it didn’t have product market fit; xxx succeeded because it achieved great product market fit. For those of us who are in the daily going-ons of things, the concept isn’t exactly prescriptive. Dan Olsen spoke of how he approached…

Shengyu Chen

Doing to think better, writing to remember. Sharing makes me feel that I am working on things bigger than me. shengyu-chen.com #build #create

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