Why does level means coding only work for one (dummy) variable?
Removing intercept from GLM for multiple factorial predictors only works for first factor in model
According to the documentation, they're pretty much interchangeable.  Is there a stylistic reason to use one over the other? Specify CSS class names on SVG paths using Illustrator Is there a way to edit SVG files in Illustrator where you can specify a CSS class for each path?  I already know in Illustrator that if you give the layer name an actual name, Illustrator will use that name as the path's ID, which is fine if you don't plan on reusing the icon more than once on the same page.  My current workaround is to just use the IDs method, but then later convert the IDs to classes in my code editor, but it's pretty annoying to have to do every time I generate my SVG sprite.  If that's currently not possible in Illustrator, are there any other apps that will allow you to specify that? Or maybe a Grunt or Gulp package?  It looks like you might be able to do it with Inkscape with a , so I might look at that if there's no other good solutions out there. Evaluate $$\int \frac{2-3x}{2+3x}\sqrt\frac{1+x}{1-x}d x$$ What substitution should I use ? $\sqrt\frac{1+x}{1-x}$ suggests $x=cos2\theta $ but its not useful in $\frac{2-3x}{2+3x}$ msiexec is command prompt software that installs an  program. But I have found that you can install an MSI file from the command line by just typing in the name of the MSI file on the command line.  But in order to uninstall the MSI file, it seems you have to call the msiexec program and give it a /x or /uninstall.  How can I uninstall an MSI from the command line without using the msiexec routine? According to the Wikipedia page for the , "Use of the comma is consistent with conventional practice" and "Use of the comma is inconsistent with conventional practice." Did the Oxford Comma come before its omission, or was the Oxford Comma traditionally omitted?  It makes logical sense that every item in a list would be separated in the same way: by a comma. If the Oxford Comma is conventionally correct, when and why did people begin to omit it? Would a 9V alkaline power a 12V DC motor? I am thinking about buying a 12V DC motor but want to keep everything, including the motor, battery, and power switch somewhat compact. I am not very knowledgeable about these kind of things and am curious whether or not my 12V DC motor would run at all on a 9V battery. Minecraft extra folders? Once I click to run minecraft a small window appears saying "Downloading runtime", then three other folders appear onto my desktop: Game, Native Log, and Runtime. This really annoys me, as I have to keep deleting them after I am done with a session of minecraft. Why is this? It never use to happen before. Virtual Host Setup Redirecting Request to Local IP address My prof gave us this definition of an Echelon system:     A system of m linear equations in n variables is called an echelon system if         m ≤ n.   Every variable is the leading variable of at most one equation.   Every leading variable is to the left of the leading variables of all lower equations.   Every equation has a leading variable.      I don't understand this definition at all.  Q1)If you have this system of equations:  $ax_1 + bx_2 + cx_3 = z$  $dx_1 + ex_2 + fx_3 = z$  its not an echelon system because of multiple equations having the same variable as the leading variable and therefore violating rule #2.  But if you switch around variables and rewrite the equation as:  $ax_1 + bx_2 + cx_3 = z$  $ex_2 + dx_1 + fx_3 = z$  It becomes an echelon system! Why would the way you write a system of equations affect its definition?  Q2)Why would point number three matter? Can't you just move around the equations so that they are in order of variables?  Q3)Why would point number four matter? If you have a equation in the system that doesn't have a leading variable can't you just disregard it? For example if you have the equation $0x = 0$ in the equation can't you just ignore it to have a echelon system since it doesn't affect the solution of the system? $_POST vs. $_SERVER['REQUEST_METHOD'] == 'POST' I want to shade the area of overlap for adjacent normal curves, shown in the lower graph. I can get shading between the first two curves but not for subsequent curves. I need shading at overlapping areas indicated by the arrows. I applied the "logic" of the first fill for the subsequent curves but that does not work.   The arrows and letters in the example image are not part of the MWE.   \documentclass{article}  \usepackage{pgfplots} \pgfplotsset{ticks=none} \pgfplotsset{compat=1.7}  \usepgfplotslibrary{fillbetween}  \pgfmathdeclarefunction{gauss}{2}{%normal distribution where #1 = mean and #2 = sd}     \pgfmathparse{exp(-((x-#1)^2)/(2*#2^2))}% }  \pgfplotsset{baseplot/.style={%     no markers,      domain=1:4.5,      samples=100,     smooth,     axis lines*=left,     height=5cm, width=12cm,     enlargelimits=upper, clip=false, axis on top,     xlabel = near ticks,     xlabel={Resource} }}  \begin{document}  \begin{tikzpicture}   \begin{axis}[baseplot]   \addplot+[name path=A]{gauss(2.7,0.4)};   \addplot+[name path=B]{gauss(3.2,0.4)};   \fill[gray!20, intersection segments ={of= B and A}]; \end{axis} \end{tikzpicture}  \vspace*{3\baselineskip}  \begin{tikzpicture}   \begin{axis}[baseplot]   \addplot+[name path=A]{gauss(1.7,0.15)};   \addplot+[name path=B]{gauss(2.2, 0.15)};   \addplot+[name path=C]{gauss(2.7, 0.15)};   \addplot+[name path=D]{gauss(3.2, 0.15)};   \addplot+[name path=E]{gauss(3.7, 0.15)};   \fill[gray!20, intersection segments ={of= B and A}];   \fill[gray!20, intersection segments ={of= C and B}];   \fill[gray!20, intersection segments ={of= D and C}];   \fill[gray!20, intersection segments ={of= E and D}]; \end{axis} \end{tikzpicture}  \end{document} Way to list "Contact Us" email address on web site, yet reduce likelihood of spam? What's a good way to list a "Contact Us" email address on a web site, while reducing the likelihood it will get spammed?  Is putting the email address in an image the best technique, or are there others? Why can we use sample variance of the treatment group to estimate population variance of the controls? Crash adding comment Why does light bend towards the normal when passing from a rarer to a denser medium? Whenever light rays are entering a denser medium they bend towards the normal.  Why do rays choose the path towards the normal? Why cannot they choose the path away form the normal? Find the exact value of the infinite sum $\sum_{n=1}^\infty \big\{\mathrm{e}-\big(1+\frac1n\big)^{n}\big\}$ How can we find the exact value of the infinite sum  $$ \displaystyle\sum_{n=1}^\infty \left\{\mathrm{e}-\Big(1+\frac1n\Big)^n\right\}? $$  This problem appears in:  , p.114. How does Java's PreparedStatement work? I am reading Boyd &amp; Vandenberghe's Convex Optimization. The authors use curved greater than or equal to (\succcurlyeq)  $$f(x^*) \succcurlyeq \alpha$$  and curved less than or equal to (\preccurlyeq)  $$f(x^*) \preccurlyeq \alpha$$  Can someone explain what they mean? I'm planning to travel to France a few times in the next few months (tourist). Since I need a Schengen visa, I just don't know how to fill out the forms (which only have questions about travel dates of ONE single trip).  How do I report that I am traveling a few times, because if I don't they might only give me a single entry visa (or a visa not valid long enough for my next trips). I can only see that I'm requesting a multiple entry visa, nothing else about how long I need it to be valid.  Do I need to provide proof of hotel/flight reservations and travel insurance for all the trips or would the first one suffice?  How do I approach this issue so that I get a Schengen visa for at least 4.5 months? I am applying in the UK at their London application centre. Is there a way to spellcheck the word under the cursor with a keyboard shortcut?