What would the punctuation be after "But I had to ask myself"
Do I need quote marks when I quote myself?
Jeffrey Wooldridge in his Econometric Analysis of Cross Section and Panel Data (page 357) says that the empirical Hessian "is not guaranteed to be positive definite, or even positive semidefinite, for the particular sample we are working with.".  This seems wrong to me as (numerical problems apart) the Hessian must be positive semidefinite as a result of the definition of the M-estimator as the value of the parameter which minimizes the objective function for the given sample and the well-known fact that at a (local) minimum the Hessian is positive semidefinite.  Is my argument right?  [EDIT: The statement has been removed in the 2nd ed. of the book. See comment.]  BACKGROUND Suppose that $\widehat \theta_N$ is an estimator obtained by minimizing $${1 \over N}\sum_{i=1}^N q(w_i,\theta),$$ where $w_i$ denotes the $i$-th observation.  Let's denote the Hessian of $q$ by $H$, $$H(q,\theta)_{ij}=\frac{\partial^2 q}{\partial \theta_i \partial \theta_j}$$  The asymptotic covariance of $\widehat \theta_n$ involves $E[H(q,\theta_0)]$ where $\theta_0$ is the true parameter value. One way to estimate it is to use the empirical Hesssian  $$\widehat H=\frac{1}{N}\sum_{i=1}^N H(w_i,\widehat \theta_n)$$  It is the definiteness of $\widehat H$ which is in question. Can you forgo your readied action to take an opportunity attack instead? Example:   Player 1 uses the ready action to do something when something happens (unimportant) Goblin, decides to charge across the battlefield and attack Player 2, but happens to cross paths with Player 1 possibly provoking an opportunity attack (here lies my question)   Could Player 1 decide to ignore their readied action and use their reaction to attack the goblin? This would of course take up their reaction so they could no longer take their readied action when it triggers.  If so; let's say it is a fireball that was readied (or any spell), would Player 1 be required to drop the fireball spell? They technically cast it as part of their ready action, but I would understand if this would be a downside to using a reaction before their readied action triggered (maybe this should be another question, but please answer it anyway and tell me if I need to create a separate one so you can answer it there too :P). Needing help picturing the group idea. I have a question;   X and Y are subgroups of a group G.  If $|X|, |Y| &lt; \infty$, show that   $|XY| = \frac{|X||Y|}{|X \cap Y|}$  but I can't really picture what it is talking about to even get started.  Is it to do with looking for different ways so combine the elements {x, y, xy} ?  Thanks I am a bit lost how one has deduced the formula for electric field with electric dipole because of some inconsistency between different sources. The  contains a delta function in the formula, but  gives only the formula without the delta function,  $$\bar{E} = -\nabla \phi = \frac{-p}{4\pi \epsilon_{0} r^{3}} ( \hat{e}_{z}-3\hat{u}_{r}(\hat{u}_{r} \cdot \hat{u}_{z}) ) $$  Is it intentionally left out?  My notes mention that the dipole is with a circular thing $P=Q d$ where $d$ is distance and $Q$ is charge. Example where union of increasing sigma algebras is not a sigma algebra Schengen Business visa without a business invitation letter Why bar magnet can produce magnetic field? How to get file creation & modification date/times in Python? I have a script that needs to do some stuff based on file creation &amp; modification dates but has to run on Linux &amp; Windows.  What's the best cross-platform way to get file creation &amp; modification date/times in Python? I always used to open a new VLC window; go to "open file"...etcetera when I wanted to watch something because when I click on a file in Windows Explorer and chose "open with" or just clicked on the file or right-clicked to choose "play with VLC" it always opened in an old already used VLC window.  Is there any way to get VLC to use a new one without always resorting to: Open VLC, "open file", find file etcetera? Abandoned colony of military engineer corps The biggest peeve is sometimes I vote up an answer mid-way through reading it, and the "don't forget to accept" message blocks the remaining text, so I scramble and triple-click it until it closes.  Anyways I frequently scan my question list and search for SO's reminders, ("Consider accepting an answer") so the "don't forget to accept" is wholly unnecessary to some, and there should be a way to disable it. Do you think so too? Can I adjust starting point when using ListPlot? Flag as Broken Link I keep finding broken links in posts, currently I add a comment in the hope someone will return to update it or if I find a link I edit the answer.   I imagine this will only increase over time so I wonder if there could be a standard way to manage this?  My idea is adding a new flagging reason like "contains broken links", then it will go to a review queue where people will be able to have a look and fix the broken links. I'm stuck in a teleporting loop. What can I do? I set a command block to /tp. It was supposed to activate only if you had 0 time left, and to activate the command block with a hopper clock to keep giving it power.   But it is not checking if you have 0 time left, so it keeps teleporting me. I can't get close enough to the command block to break it, so I'm stuck in a neverending teleport loop.  Any ideas? Where should I start learning? There are various topics to learn like Objects, Classes, Apex, Visualforce, SOSL, SOQL, Triggers, etc. There are so many options out there to start learning. I couldn't decide what topic to learn first, and then step by step get proficiency in all aspects of Saleforce. why are the best questions the ones which have been closed? Why are there scenes that will not render on GPU but will render fine on CPU? I've already tried GPU Rendering and it seem to be twice as fast as the CPU. However I have some situation where tried to render on the GPU, but it doesn't do anything. When I switch to CPU it renders.  I have some fur texture/materials using particle systems. I wonder if that causes the GPU not to render, I'm not really sure. What are the correct version numbers for C#? When overriding equals in Java, why does it not work to use a parameter other than Object? I ran into an interesting behavior recently.  It seems that if I override .equals() to take a parameter other than Object, it doesn't get called.  Can anyone explain to me why this is happening?  It seems to violate my understanding of polymorphism in OOP, but maybe I'm missing something.  Here's much simpler code that shows what I'm seeing:  public class MyClass {   private int x;   public MyClass(int n) { x = n; }   public boolean equals(Object o) { return false; }   public boolean equals(MyClass mc) { return x == mc.x; }   public static void main(String[] args) {     List&lt;MyClass&gt; list = new ArrayList&lt;MyClass&gt;();     list.add(new MyClass(3));     System.out.println("Contains 3? " + list.contains(new MyClass(3)));   } }   When this is run, it prints "Contains 3? false".  It looks like the equals(Object) function is called, even though there is another that would work.  By contrast, if I write equals like this the code works as expected:  public boolean equals(Object o) {   if(!(o instanceof MyClass))     return false;   MyClass mc = (MyClass)o;   return x == mc.x; }   Why isn't it figuring out which version of the function to call based on the type of the parameter? What is the difference between Affection and Friendship, if any? I've risen Pokemon Amie Affection to 5 hearts on my Riolo in the hopes that it will evolve as soon as it levels up, but I'm not certain that this is the same thing as friendship, and I'd like to not waste a level.  My question is this: What is the difference between Pokemon Amie Affection and the Friendship stat?