I'm reading Tsay's time series book. The ACFs and PACFs looks like this:   My question is: how to specify an ARMA model (p=?, q=?) based on the above figure? The author did give some ideas, but I'm totally confused. The first eight lags of PACFs are significant. This implies that q (order of MA part) >0. Why? The PACFs do not follow a simple exponentially decaying pattern. This means p (order of AR part) >1. Why? Somehow I think AR(8) would be a good choice. Is it reasonable?    Is there any general rule about how to specify an ARMA model? Thanks!
The  page says that Box-Jenkins is a method of fitting an ARIMA model to a time series. Now, if I want to fit an ARIMA model to a time series, I will open up SAS, call proc ARIMA, supply the parameters $p,d,q$ and SAS will give me AR and MA coefficients. Now, I can try different combinations of $p,d,q$ and SAS will give me a set of coefficients in each case. I select the set with the lowest Akaike information criterion.  My question is: where in the above procedure did I use Box-Jenkins? Am I supposed to use Box-Jenkins to come up with initial estimates of $p,d,q$? Or did SAS use it internally somehow?
"Was" or "were" for "half a dozen" In Microsoft Word, the following sentence is flagged.  It tells me to use "was" instead of "were"     There were half a dozen books strewn about the floor.   I would think that you would use "were" since it's a quantity more than one.  You wouldn't say, "There was twelve books strewn about the floor."  Does the use of the "half" modify it somehow? Who owns R2-D2 & C-3PO in the Prequel trilogy? Is there any concrete evidence that Anakin officially owned R2-D2 or C-3PO?  I found this episode of Star Wars: Clone Wars that shows it, but it's fairly vague... running a bash file states:date: command not found I've installed a version of Ubuntu Server and although I'm fairly still fresh with Ubuntu, I'm trying to create a bash file to run a program in the background. More importantly, I'm trying to get a file nameto display correct and create it before I start running the program (I like my debug stuff).  However, here is my bash script:    #!/bin/bash  PATH="/var/log/servers/Game/"  FILENAME="startup"  EXT=".log"  DATE=$(date +%d-%m-%Y)  NEWFILE=${PATH}${FILENAME}_${DATE}${EXT}   I have verified that the file does exist in the PATH directory. However, the issue is with the date command. When I run the script bash -x game.sh this is what is displays.   + PATH=/var/log/servers/Game/  + FILENAME=startup  + EXT=.log  ++ date +%d-%m-%Y  game.sh: line 5: date: command not found  + DATE=  + NEWFILE=/var/log/servers/Game/startup_.log  + echo /var/log/servers/Game/startup_.log   I don't understand why it would say the command doesn't work, when I can go to the main console and run date and get a valid response.  Any help is greatly appreciated! How do I programmatically determine operating system in Java? I would like to determine the operating system of the host that my Java program is running programmatically (for example: I would like to be able to load different properties based on whether I am on a Windows or Unix platform). What is the safest way to do this with 100% reliability? How do I reset a lost password (using recovery mode requires me to type the password)? Where can I get freely available audio, graphics, and other resources for games? I've tried to setup an autologin, but that isn't possible, because my home is encrypted. What are the reasons for this?  PS. Here I have described my problem: . 2.5 GB usable out of 4 GB of ram How to use a file in a jar as javax.net.ssl.keystore? I'm trying to do something like   URL clientks = com.messaging.SubscriptionManager.class.getResource( "client.ks" ); String path = clientks.toURI().getPath(); System.setProperty( "javax.net.ssl.keyStore", path);   Where client.ks is a file stored in com/messaging in the jar file that I'm running.  The thing that reads the javax.net.ssl.keyStore is expecting a path to the client.ks file which is in the jar. I'd rather not extract the file and put in on the client's machine if possible. So is it possible to reference a file in a jar?  This doesn't work as getPath() returns null. Is there another way to do this? Cannot Buy Land in Falkreath How can I draw simple trees in LaTeX? I need to draw a tree, and constantly using dotty and including the PNGs is starting to be a pain. Is there a way to get LaTeX to draw it's own trees that doesn't involve learning an entirely new language like TikZ? How about a "Irritable" badge for someone who downvotes often? EDIT : How about a forced comment   dialog...which forces the user's to   comment when they downvote otherwise   they can't....right now it just shows   a popup to suggest posting a   comment...maybe this is little too   strict...but i just find it annoying   when ppl downvote and leave no   comments....   How about having a badge "Irritable" for a user who downvotes over 20 times in a month and then have maybe further "Furious" for over 50 downvotes in a month....just a fun suggestion...since i see people downvote like crazy at times...there should also be a way to downvote a comment i think in addition... How can you enumerate an enum in C#?  E.g. the following code does not compile:  public enum Suit {     Spades,     Hearts,     Clubs,     Diamonds }  public void EnumerateAllSuitsDemoMethod() {     foreach (Suit suit in Suit)     {         DoSomething(suit);     } }   And it gives the following compile-time error:     'Suit' is a 'type' but is used like a 'variable'   It fails on the Suit keyword, the second one. $M + N$ and $M \cap N$ are finitely generated $A$-modules implies $M$ and $N$ finitely generated using exact sequences Let $0 \to M_1 \to M \to M_2 \to 0$ be an exact sequence of $A$-modules.  i) Prove: If $M_1$ and $M_2$ are finitely generated, then $M$ is too.  ii) Let $M$ and $N$ be sub-modules of an $A$-module $L$. Assume that $M+N$ and $M\cap N$  are finitely generated $A$-modules. Prove that $M$ and $N$ are finitely generated $A$-modules.  If have proved the first part, but i don't see how to do the second part. I tried to use the first part, so to find an exact sequence with $M$ in the middle and finitely generated modules in place of $M_1$ and $M_2$, but I can't find a surjective map $M \to P$ (for some f.g. $A$-module) in the sequence:  $$0 \to M\cap N \to M \to P \to 0$$  any hints/help would be appreciated. This bug was found on a couch in . The couch, and the two beds in the room show no signs of other bugs. Is this a bed bug that I should worry about or something harmless? It was slightly larger than a common tick. Conky Widgets are Opening in their Own Windows I just upgraded to 16.04 and I'm getting all my customization set up again, but it seems that most Conky widgets are opening in their own window, instead of just appearing on the Desktop; although some are working correctly.  For example:  LSD (working properly):    Seamod (not working, opening in own window):    Since it's not affecting every single widget, I assume it could be an issue with the conkyrc with the widgets that aren't working, but this also never happened in 14.04 so I wasn't sure if maybe there was some compatibility issue in 16.04. My Google-fu has failed me in finding a solution.  If anyone can point me in the right direction, it would be much appreciated! :) Using a variable in a SELECT statement? public static void handleCaseComment(CaseComment caseComment) {    User[] users = [SELECT LastName FROM User WHERE Id = caseComment.CreatedById LIMIT 1]; }   This gives me the following error:  unexpected token: 'caseComment.CreatedById'   How do I use the value of the variable caseComment.CreatedById in a SELECT statement? Confused about AMD/Intel When I go to the downloads page to get Ubuntu, it automatically downloads the AMD version, but my computer has no hardware with AMD on it. I only have Intel and Nvidia. Also, when I install this AMD version on my computer, it works (other than the constant random freezing of the computer when I use Ubuntu). I don't really understand why the amd version works on a computer with an intel processor. Let $f:[0,+\infty)\to\Bbb R$ be a function bounded on each finite interval. I want to show that if $\lim\limits_{x\to+\infty}[f(x+1)-f(x)]= L,$ then also $\lim\limits_{x\to+\infty}\dfrac{f(x)}x = L$ I installed the latest Ubuntu today, 15.04. Spotify has stopped working. How can it be made to work again?  The Unity bar flashes green 4 or 5 times and then stops flashing. There are no error messages. It was installed successfully and played well on 14.10 till the upgrade a few hours ago. It just does not appear on the screen.