Some research doesn’t really start with a question, but a survey form waiting to be filled. The pattern is predictable: pick a “socially important” topic — say, “Do people feel more ethical after recycling a paper cup?” Then split participants into two groups. One group watches a short clip of someone recycling. The other sees the same cup tossed in the trash. Everyone rates their feelings on a 1-to-7 scale. And just like that, we’ve produced “evidence.” ...

The Wall-Street Journal has this wonderful video The Money-Making Secrets Behind Hotel Design: “From vanishing minibars to disappearing closets, hotel rooms are shrinking. With the rise of Airbnb and hotel occupancy rates plateauing, operators are on the hunt for the most profitable design to maximize profits. Take Marriott’s Moxy brand, for example — its rooms are less than half the average size yet can generate up to 20% more revenue than its peers.” ...

A pause on my econometric homework, here’s what seems to have happened:

The music industry and the academia has something in common: composers/academics are basically, content creators. Looking into a bit music history helps understand the general dynamic of both worlds. From the book The Orchestra And Orchestral Music (W. J. Henderson, 1899): The older composers are like ancient history; one must have sufficient information to know what to accept and what to reject in order to read them with advantage. (From chapter The Strings, where the author is trying to make a point on which composer to look to to study the best string orchestration) I think there is something profound in how the author view (and try to let the readers understand his way of viewing) the development of woodwinds and harmonies through time: ...

Stephen Dubner is in town today for the 20th anniversary of Freakonomics, at an open conversation event hosted by Chicago Humanities. It’s even better than a live podcast. Slay. Stephen called the podcast industry in general as one of Steve Jobs’ greatest inventions. By introducing a simple but open content-upload API, that once “stupid purple app” slashed the cost of journalism to nearly zero — making great ideas freely available to anyone, anywhere. ...

Class note from Price Theory course. Consider an individual looks to buy $m$ goods. Let there be nice assumptions: Continuous: that consumption can be expressed as $x\in \R^m$. (Strictly?) concave utilities. Linear budget: $p\cdot x \le \texttt{Budget}$. Back of (a big) envelope Let $\mathbf x^H(p, u), \mathbf x^M(p, I)$ be the Hicksian and Marshallian demand functions. If we focus on one single good $i\in [m]$, and with a tiny abuse of notation, we can write $$ \begin{align*} & x_i^{H(\bar U, p_{-i})}(p_i) :=x_i^H(p_i, p_{-i}, \bar U)\cr & x_i^{M(I, p_{-i})}(p_i) :=x_i^M(p_i, p_{-i}, I) \end{align*} $$ When economists scribble a downward sloping demand curve on a 2D plane, we are basically holding $(\bar U, p_{-i})$ (or $(I, p_{-i})$) fixed and drawing the Hicksian demand curve $D^H:\lbrace (x_i^H(p_i), p_i)\rbrace$ or Marshallian demand curve: $D^M:\lbrace(x_i^M(p_i), p_i)\rbrace$. ...

The TV series Etoile (2025) ends with a solo modern ballet choreographed by Christopher Wheeldon, to the music by Sparks, singing, “I married myself, I’m very happy together. Candlelight, dinner’s home, lovely times…” Seems a bit absurd a first sight, but It’s a very very beatiful and deep concept explored here. “To marry oneself means to fully accept one’s own flaws, either by looking past them or taking the necessary steps to improve. No wonder a cloud of bliss saturates the song. Not every marriage is as healthy as the joyous union of self meeting self. And “this time, it’s gonna last forever.” ‘Til death do we part, indeed.” (Reddit) ...

Today the U of Chicago Symphony Orchestra rehearses Tchaikovsky’s 5th Symphony. Nooooooo. The French horn solo at the beginning of the 2nd movement is one of Tchaikovsky ’s most beautiful melody passages. This pure beauty pushed beyond imagination, in my opinion, it is love.

Professor Aumann’s most highly cited paper “AGREEING TO DISAGREE” only has four pages… Slay. Here’s how I understand Aumann’s common knowledge: Let the state of the world be a finite set $ \Omega $. Each agent $ i $ has an information structure represented by a partition $ \mathcal{P}_i $ over $ \Omega $. For each state $ w \in \Omega $, let $ P_i(w) \in \mathcal{P}_i $ be the element of the partition that contains $ w $. For simplicity, we consider two agents, but the results extend naturally to any number of agents. ...

The Chicago Price Theory (2019) Chapter 8 Location Choice features the following model: $$ \begin{align*} \max_{C, L, t} & \ U(C, L)\cr s.t.&\ C =\alpha + w(24 - L - t) - R(t)\cr & L, t\in [0, 24], C\ge 0. \end{align*} $$ where, $C$ is consumption (think of it as money), $L$ is leisure time, and $t$ is travel time, $R(t)$ is the rent function, assume it be decreasing. $w$ is individual’s wages. Being nice today, let’s assume $U$ is strictly concave. ...