Variables: lprice = log(price of house) ldist = log(distance from incinerator) lintst = log(distance from interstate)   1st regression    2nd regression:    In the 2nd regression I included lintstsq, which is the squared lintst from the 1st regression, and suddenly ldist and lintst become significant and their coefficients change. This doesnt make sense, how come the statistical package couldnt pick up that lintst was significant until I included its squared form, lintstsq? Can someone provide insight into this?  My lecturer's comment on this was:     This makes sense. Being close to the interstate is useful, especially   for commuters who use the interstate to get to work. But being too   close is not good owing to the noise and pollution. If distance from   the incinerator site and distance to the interstate are correlated, we   need to get the model specification with respect to the latter right   in order to identify the effect of the former.   which doesnt help explain much(or does it?)
I have what is probably a simple question, but it is baffling me right now, so I am hoping you can help me out.  I have a least squares regression model, with one independent variable and one dependent variable. The relationship is not significant. Now I add a second independent variable. Now the relationship between the first independent variable and the dependent variable becomes significant.  How does this work? This is probably demonstrating some issue with my understanding, but to me, but I do not see how adding this second independent variable can make the first significant.
I have a class with two class methods (using the classmethod() function) for getting and setting what is essentially a static variable.  I tried to use the property() function with these, but it results in an error.  I was able to reproduce the error with the following in the interpreter: class Foo(object):     _var = 5     @classmethod     def getvar(cls):         return cls._var     @classmethod     def setvar(cls, value):         cls._var = value     var = property(getvar, setvar)  I can demonstrate the class methods, but they don't work as properties: &gt;&gt;&gt; f = Foo() &gt;&gt;&gt; f.getvar() 5 &gt;&gt;&gt; f.setvar(4) &gt;&gt;&gt; f.getvar() 4 &gt;&gt;&gt; f.var Traceback (most recent call last):   File &quot;&lt;stdin&gt;&quot;, line 1, in ? TypeError: 'classmethod' object is not callable &gt;&gt;&gt; f.var=5 Traceback (most recent call last):   File &quot;&lt;stdin&gt;&quot;, line 1, in ? TypeError: 'classmethod' object is not callable  Is it possible to use the property() function with @classmethod decorated functions? Understanding of the theorem that all norms are equivalent in finite dimensional vector spaces The following is a well-known result in functional analysis:     If the vector space $X$ is finite dimensional, all norms are equivalent.     Here is the standard proof in one textbook. First, pick a norm for $X$, say  $$\|x\|_1=\sum_{i=1}^n|\alpha_i|$$ where $x=\sum_{i=1}^n\alpha_ix_i$, and $(x_i)_{i=1}^n$ is a basis for $X$. Then show that every norm for $X$ is equivalent to $\|\cdot\|_1$, i.e.,  $$c\|x\|\leq\|x\|_1\leq C\|x\|.$$ For the first inequality, one can easily get $c$ by triangle inequality for the norm. For the second inequality, instead of constructing $C$, the  is applied to construct a contradiction.   The strategies for proving these two inequalities are so different. Here is my question,      Can one prove this theorem without Bolzano-Weierstrass theorem?   UPDATE:     Is the converse of the theorem true? In other words, if all norms for a vector space $X$ are equivalent, then can one conclude that $X$ is of finite dimension? Finding places to play Magic the Gathering games A friend of mine recently got MTG for the XBox and is talking us into getting real cards.  I'm all up for starting but I dread the idea of playing the same two people over and over with no change epically since one of them is over competitive and exploits every loophole he can to win.  Does anyone know of any a reliable (not just google it) way to find places where people play MTG? Is it worth it to buy an FD-EOS adapter, or is it better to exchange a misbought lens? I recently bought a manual-focus (since manual doesn't bother me) . However, I didn't notice at the time of purchase that it was an FD lens. (I'm a hobbyist; I didn't know Canon had actually changed lens mounts at some point.)  On the one hand, I kind of want to experiment with this guy. And quality FD lenses are relatively cheap on the used market, so if the adapters were worth it, I could probably get more (and more varied) glass. On the other hand, everything I read about the FD-EOS adapters is highly contradictory. As in, some people swear by them, and others think they're outright tripe.  I am still within the exchange period, and can easily exchange this lens for this  that I'd been tossing up about buying anyway, as they are the same price.  Which would be the wiser choice? What does **Ens** stand for? Earlier someone was asking about the category "Ens" described in Categories for the Working Mathematician. My question is more basic: What does Ens stand for?  Most of the categories have names that are self explanatory, and maybe this one does too.  But for the life of me I can't think of it, and a Google search was no help. How to split bibliography into "works cited" and "works not cited"? I need two bib-like sections: a "References" giving works explicitly cited in my text, and a "Bibliography" (or "Further reading" if you prefer) giving everything from my bibfile that didn't already appear in "References". The first is of course completely standard, but the second... I'm stumped.  Further loose constraints: I'm somewhat committed to biblatex and the biblatex-apa style. But I'll happily accept an answer not related to them if there's any chance I can adapt it. A continuous mapping is determined by its values on a dense set How to get back a declined Outlook invitation I accidentally clicked "decline" on an Outlook invitation and now I can't reverse it -- the event has completely disappeared from my calendar!  How can I get back the event invitation and change my "Decline" to "Accept" or "tentative"? What does the x mean on MCB? Any clue? Or is it just there for better visual? How can I get form data with JavaScript/jQuery? The question  got me curious and thinking about the following:   For which $n$ and $k$ are there nontrivial homomorphisms from the symmetric group $S_n$ to the cyclic group $\mathbb{Z}/k\mathbb{Z}$ of order $k$? I'm thinking it might be an open problem. Is this a problem with a known solution? If so, how can we prove it?   Thanks! Close locked file in Windows Share using Powershell and Openfiles I work with a lot of folder shares, but there are a bunch of locked files which have been opened by some other process.  I need to close those files. So far I've been using MMC - System Tools - Shared Folders - Open Files.  It would be far more convenient if I could use PowerShell to filter the list/table retrieved by OpenFiles.exe and once I get the file ID close it with net file  /close, or some other PS native means to similar effect.  I am new to PowerShell, so I wonder if there is a way to create a PS script that receives the file's path and then used the file ID to close that file? After monitor calibration colors on my two monitors are still different, why? I have a pair of pretty nice monitors (HP ZR30w) which I calibrated with a pretty good calibrator (i1-Pro) and after I calibrated both they still show colors every so slightly differently.  My left monitor has a little more magenta color to it in photos.  Is monitor calibration only ment to get things 'close'?  Other people in the office have experienced similar issues with their pairs of monitors, both HP ZR30w and Dell 3007WFP-HC monitors.  If I can't even get colors to match between my two exact same monitors connected to the same computer I have little confidence that colors on my monitors will look the same on somebody else's calibrated monitor :p MTG: Sideboard if maindeck has more than 60 cards I had created the xml document with xml version="1.0".  In that document I need to use the greater than symbol &gt; and less than symbol &lt;.  How should I include those symbols? It's not working.  &amp;gt; and &amp;lt; are not working for me.  Is there any special encoder for this? Textbooks on linear regression with least squares How to validate phone numbers using regex Show timestamp of a vote in the tooltip when mousing over it Trouble creating 3TB ext4 partition due to msdos-partition-table-imposed error Windows 7 time issues