A list of the most recently updated pages.

 Jan 11, 2022 » Journal Reviews 5 min; updated Jan 15, 2022 Link Prediction Given network-structured data, predict whether a link exists between two nodes. General types of prediction tasks on graphs: graph-level (e.g. will a molecule bind to a receptor implicated in a disease?), node-level (e.g. what is the identity of each node?), and edge-level (e.g. does this edge exist; what value does it have?). Applications include: predicting drug-drug interactions (common in treating patients with complex/co-existing diseases) as they may cause changes in the drugs' pharmacological activity .... Mar 29, 2020 » Introduction 1 min; updated Jan 11, 2022 Investor Key Fund/Vehicle Period Annualized Returns After Fees Jim Simons Medallion Fund 1988 – 2018 (30) 39.1% George Soros Quantum Fund 1969 – 2000 (31) 32.0% Steven Cohen SAC 1992 – 2003 (11) 30.0% Peter Lynch Magellan Fund 1977 – 1990 (13) 29.0% Warren Buffett Berkshire Hathaway 1965 – 2018 (53) 20.5% Ray Dalio Pure Alpha 1991 – 2018 (27) 12% But time in the market is king - at least that’s what Malkiel taught me.... Oct 9, 2017 » Bayesian Rating 1 min; updated Jan 11, 2022 Allows us to weight by review population size. Let $$n_i$$ be the number of reviews that item $$i$$ gets, and let $$r_i$$ be the naive average rating of item $$i$$ Let $$N$$ be the total number of reviews across brands, i.e. $$N = \sum_{i} n_i$$ Let $$R$$ be the average rating over all items across brands, i.e. $$R = \frac{1}{N} \sum_{i} n_i r_i$$... Nov 13, 2017 » Infection Models: SI, SIS, SIR 2 min; updated Jan 11, 2022 Models state transitions through differential equations over continuous time $$t$$. Commonly used to model the spread of diseases. Possible states that proportions of the population could be in at time $$t$$ are: susceptible $$S(t)$$, infected $$I(t)$$, and recovered $$R(t)$$ The SI Model Assumes that one can only move from state $$S$$ to state $$I$$, with probability $$\beta$$. $$S'(t) = - \beta S(t) I(t);\ \ \ \ I'(t) = \beta S(t) I(t)$$... Nov 13, 2017 » The Contagion Model 1 min; updated Jan 11, 2022 For any node to possibly flip, there must be some nodes that have the disease at $$t = 0$$. These nodes are called seeders. Brings topology into the picture: flip iff $$p$$ of your neighbors have flipped. Assumes that each node has the same flipping threshold $$p$$ Will the Whole Network Flip? For a cluster of nodes, let $$d_i$$ be the fraction of the neighbors of $$i$$ that are in the cluster.... Nov 13, 2017 » Modeling Influence with Graphs 3 min; updated Jan 11, 2022 Graphs, $$G = (V, E)$$ $$N \times N$$ Adjacency Matrix $$N \times L$$ Incidence Matrix $$A = \begin{bmatrix}0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 1 & 0 & 0 & 0 \\ 0 & 0 & 0 & 1\end{bmatrix}$$ $$\hat{A} = \begin{bmatrix}1 & 0 & -1 & 0 \\ -1 & 1 & 0 & 0 \\ 0 & -1 & 1 & -1 \\ 0 & 0 & 0 & 1\end{bmatrix}$$ $$V$$ = set of $$N$$ nodes$$E$$ = set of $$L$$ links $$A_{ij} = 1$$ iff $$(i, j) \in E$$Note that $$A$$ need not be symmetric for directed graphs.... Nov 13, 2017 » Examples of Influential Power 1 min; updated Jan 11, 2022 Night Ride - April 18, 1775 Paul Revere and William Dawes. Revere alerted influential militia leaders on his ride to Lexington. Led to American forces winning the first battle of the Revolutionary War. Malcolm Gladwel describes Paul Revere as a “Connector” in The Tipping Point Medici Family in Renaissance Florence 15 prominent families Medici had 50% higher degree than Strozzi and Guadagni. But the Medicis influential power was much greater than explained by the 50%.... Jan 2, 2022 » Modular Arithmetic 4 min; updated Jan 10, 2022 Main resource: . What is Modular Arithmetic? Where $$A$$ and $$B$$ are integers, we can write: $$\frac{A}{B} = Q \text{ remainder } R$$ Using the same $$A, B, Q, \text{ and } R$$ as above, we have: $$A \text{ mod } B = R$$ $$A \text{ mod } B$$ can be visualized as taking $$A$$ steps on a clock that runs from $$0$$ to $$B-1$$. If the number is positive we step clockwise, if it’s negative we step counterclockwise.... Aug 2, 2021 » Misconstructions and Misconceptions 1 min; updated Jan 10, 2022 A collection of instances in which I believed something that wasn’t true. A reminder to read not to believe, but to weigh and consider . The Four Color Theorem does not claim that 4 colors suffice to color a planar map. Instead, 4 colors are sufficient to color any planar graph so that no two vertices connected by an edge are colored with the same color. For any $$n$$, there is a map that requires at least $$n$$ colors.... Jan 27, 2020 » Tech and Democracy 5 min; updated Jan 7, 2022 Political Ads Cambridge Analytica (CA) paid people to take in-app survey; mined FB profile data including friends' data; crafted tailored sensitive ads to sway-able voters. Elections are about emotions, not facts. Data science and social media can help us make sense of and manipulate the chaos. An alternative argument. Political misinformation is: Weak in high profile partisan races because pre-existing beliefs hardly change Strong when people don’t have string pre-existing opinions, e.... Oct 4, 2021 » Online Markets 4 min; updated Jan 7, 2022 WWW ‘21: The Web Conference 2021 REST: Relational Event-Driven Stock Trend Forecasting REST, an event-driven stock trend forecasting framework, that overcomes two limitations of existing event-driven models. Models the stock context, and learns the effect of event information on the stocks under different contexts. Constructs a stock graph and designs a new propagation layer to propagate the effect of event information from related stocks. The value of stock trend forecasting is not unanimous, e.... Oct 4, 2021 » Journal Reviews on Fairness 4 min; updated Jan 7, 2022 WWW ‘21: The Web Conference 2021 User-oriented Fairness in Recommendation Showed that active users who only account for a small proportion enjoy much higher recommendation quality than the majority inactive users. They propose a re-ranking approach by adding constraints over the evaluation metrics. There’s a subtlety here. Although the active users are the minority, the recommender considers them the majority as they are the ones providing a lot of the training data.... Oct 13, 2021 » Towards a Collaborative Web Browser 3 min; updated Jan 7, 2022 One of the grand dreams of the web is bringing people together so that they may find relevant information. Sometimes this is implicit, e.g. Google Search’s PageRank learns from inter-page links which are mostly made by people, but there may be room for explicit collaboration when navigating the web. This section explores such explicit attempts. A Group Asynchronous Browsing (GAB) Server Premise: Users submit their subject hierarchies (bookmarks) to the GAB server.... Dec 15, 2020 » Politics Potpourri 3 min; updated Jan 7, 2022 State Surveillance In the aftermath of the Capitol insurrection, FBI was contacting people whose cellphones pinged cell towers near the Capitol during the riots. A powered mobile phone always sends signals to one of the closest base stations. Given multiple base stations, the angle and time of arrival, and location signatures of each cell location can be used to locate a mobile device. The higher the density of cell towers, the more precise the calculated location.... Jan 2, 2022 » 05. Rethinking Identity 6 min; updated Jan 3, 2022 How Beliefs Become Identities Didn’t have priors on this. In retrospect, I could have asked: how can I differentiate between a belief and an identity? What are the consequences of a belief becoming an identity? Feeling under siege from a hostile world may crystallize a belief into an identity, e.g. formula-feeders feeling judged as bad mothers; evangelical christians feeling alienated by legal and cultural changes like legal abortion, gay marriage and sexualized content in the media.... Jan 2, 2022 » 04. Changing Your Mind 6 min; updated Jan 2, 2022 How to Be Wrong found that experts were barely able to forecast better than random chance. However, a small subset of people (coined “superforecasters” ) were better. In a competition, they beat teams of top professors and CIA professional analysts. These superforecasters were not smarter than everyone else nor did they have more knowledge/experience, they were great at being wrong. Change your mind a little at a time. Seeing the world in shades of grey is less stressful, as the experience of encountering evidence against one of your beliefs is not high stakes.... Dec 28, 2021 » 02. Developing Self-Awareness 8 min; updated Jan 2, 2022 Signs of a Scout These Don’t Make You a Scout Feeling objective. The more objective you feel, the more you trust your own intuitions and opinions as accurate representations of reality, and the less inclined you are to question them. Being smart and knowledgeable. It’s not a case of “if people were smarter and well-informed, they’d realize their errors”. For example, found that polarization (on political fronts) on anthropogenic climate change increases as scientific intelligence increases.... Jan 1, 2022 » 03. Thriving Without Illusions 3 min; updated Jan 1, 2022 Coping with Reality This chapter felt a bit vacuous with its use of anecdotes to advance points. Criticism of studies that argue that self-deception makes us happier: conflation of positive illusions and positive beliefs; unfounded definitions of what counts as self-deception; results that can be equally well-explained by something else. There are alternative coping strategies that don’t involve self-deception: making a hypothetical plan about some unpleasant and unavoidable thing; noticing silver linings but not to the point of sweet lemons; admitting that things could be worse.... May 2, 2020 » On Learning 11 min; updated Dec 29, 2021 Mental Attitude While Learning Distinguish Mere Facts From Conclusions or Opinions Discriminate between mere statements of facts, necessary conclusions which follow therefrom, and mere opinions which they seem to render reasonable. There’s no need to perform an experiment to verify that the atomic weight of oxygen is 16. That the sum of the angles of a plane triangle equals two right angles is not a mere fact, but an inevitable truth....