Interaction term and main effect multicollinearity
Collinearity diagnostics problematic only when the interaction term is included
Definition of Significant Figures In my textbooks,  are defined as:   “Significant figures by definition are the reliable digits in a number that are known with certainty.”  “A significant figure is the one which is known to be reasonably reliable.”    Reliable means giving the same result on successive trials or reliable information can be trusted to be accurate. However, at the end of each of the two definitions it is also written that ‘the last digit of a number is generally considered uncertain in the absence of qualifying information.' For example if the mass of an object is 12.248 gm, the last digit which is ‘8’ is uncertain by plus or minus 0.001 gm. This uncertainty is unreliability in the information. So, the digit ‘8’ is uncertain, and thus according to the definition 1 it is not a significant figure. However, the rules for significant figures say that ‘non-zero digits are all significant’. Due to the last digit ‘8’, if the object was weighed with careful handling minimizing the chances of error, the figures preceding ‘8’ that are (1, 2, 2, 4) are certain and reliable. If the mass of another object is 2 gm, then it is uncertain by plus or minus 1 gm i.e. its mass could be 3 gm or could be 1 gm.  ‘2’ is therefore not certain! What is the reason that significant figures are defined to be the reliable digits in a number? In what sense they are said to be reliable? What is a contrast matrix? What exactly is contrast matrix (a term, pertaining to an analysis with categorical predictors) and how exactly is contrast matrix specified? I.e. what are columns, what are rows, what are the constraints on that matrix and what does number in column j and row i mean? I tried to look into the docs and web but it seems that everyone uses it yet there's no defition anywhere. I could backward-engineer the available pre-defined contrasts, but I think the definition should be available without that.  &gt; contr.treatment(4)   2 3 4 1 0 0 0 2 1 0 0 3 0 1 0 4 0 0 1 &gt; contr.sum(4)   [,1] [,2] [,3] 1    1    0    0 2    0    1    0 3    0    0    1 4   -1   -1   -1 &gt; contr.helmert(4)   [,1] [,2] [,3] 1   -1   -1   -1 2    1   -1   -1 3    0    2   -1 4    0    0    3 &gt; contr.SAS(4)   1 2 3 1 1 0 0 2 0 1 0 3 0 0 1 4 0 0 0 How does delete[] know it's an array? Define ≡ in this situation? It's not consistent to leave an edit pending for approval (thus not making available for everyone else and locking its state) after a user who has those privileges have given his endorsement.   You could say why don't I improve the edit, but that makes no sense for something that is correct and it would not follow the "keep it simple" policy.  Update:  This is the current time line:   Someone who doesn't know about formatting makes a question. It's not legible A user without edit privileges amends the formatting. The correction is not visible, still not legible. I see the question and the pending revision and then cast my approval. It doesn't take effect yet, still not legible. Even for me if I didn't take care of copying the question source because it disappears from my own revision page!   I might agree that one's approval is indicative of both revision's quality and editor's competence. But we should retain that the main objective is to ask and answer questions. So, I propose this model:   Someone who doesn't know about formatting makes a question. It's not legible A user without edit privileges amends the formatting. The correction is not visible, still not legible. A user with edit privileges cast his approval. Revision takes effect. Although it keeps the pending approval (the Edit (1) button). If a second user with edit privileges cast a rejection, it also takes effect as a rollback. problems installing mathtools how to create shortcode in wordpress So I have the following code:   &lt;span class="delete"&gt;&lt;a onclick="return confirm('Are you sure?');" href="&lt;?php echo wp_nonce_url( add_query_arg( array( 'action' =&gt; 'my-delete-product', 'product_id' =&gt; $post-&gt;ID ), my_get_navigation_url('products') ), 'my-delete-product' ); ?&gt;"&gt;&lt;?php _e( '삭제', 'my' ); ?&gt;&lt;/a&gt; | &lt;/span&gt;   It is a simple button.  I want to make this into a shortcode so that I can use it anywhere where appropriate.  Any suggestions?  Thanks. Can I watch the progress of a `sync` operation? How to ensure that all traffic goes through VPN connection once it has been started? I connect to the internet through a VPN provider along with other precautions in order to ensure privacy (against traffic analysis by agencies of a repressive government). I currently use  to configure and establish the VPN connection. Tunnelblick does not allow automatically connecting to the provider at or before login so I need to connect manually each time, and sometimes the connection is lost.  I need any and all traffic to go through the VPN connection at all times; whenever the VPN isn't connectable for whatever reason, I want the fallback to be no connection. I need to ensure   that OS X does not connect to the internet on my regular internet connection, or at all, during boot (until the login screen, for time synchronization and other possible "call home" stuff etc.). What services, if any, try to do this, and how can I practically analyze and change what's going on with networking during boot? Is there a way to connect to VPN earlier than right after login? that if my VPN connection is temporarily lost, applications do not continue to communicate over my regular unencrypted connection.    I basically want the system to act as if the network connection is lost altogether if the VPN connection fails, but currently they just continue to work as if nothing happened. What can I do to my system so that once a VPN is established, all traffic can only flow through that connection and no traffic can flow if the connection drops? Proving that $\frac{1}{1\cdot 2} + \frac{1}{2\cdot 3} + \frac{1}{3 \cdot 4} +\ldots + \frac{1}{n(n+1)} = \frac{n}{n+1}$ How would we go about proving that $$\frac{1}{1\cdot 2} + \frac{1}{2\cdot 3} + \frac{1}{3 \cdot 4} +\ldots +\frac{1}{n(n+1)} = \frac{n}{n+1}$$ I duplicated a few objects with Alt+D and now I want to apply some modifiers to them, however I can't, because they are multi-user objects.  I tried U > Objects but I still can't apply the modifier.  How to make multi user objects single user? How do I expire by type in .htaccess for remote loaded Google fonts? Is it possible to set expire by type for remote fonts or Google analytics? I'm getting this report from GTMetrix and everything I've tried isn't working. Suggestions?  There are 4 static components without a far-future expiration date. http://fonts.googleapis.com/css?family=Open+Sans:300 http://fonts.googleapis.com/css?family=Roboto&amp;subset=latin,latin-ext http://www.google-analytics.com/ga.js http://www.google-analytics.com/analytics.js   All of my other expires are working fine.  But apparently this type of thing isn't right?  ExpiresByType application/x-font-woff "access 1 year" ExpiresByType application/font-woff "access 1 year"   What should I do? I installed ubuntu 16.04 LTS, but there is no ubuntu one software, not in ubuntu software center also..Though it is showing selected in unity tweak tool.How can I get it. Please reply. How do I get back my suspend option in Gnome Shell? With the new version of Gnome Shell in Ubuntu 12.10 they turned  around by just displaying the shutdown option which becomes suspend on pressing Alt.  How do I get back my beloved suspend option? Ubuntu copy dialogue stops at the last moment for a long time Whenever I try and copy a file to an USB flash disk, the progress bar runs till the end very fast and stops for an indeterminable time before it is complete.  Is there an issue with ubuntu or my flash disk is what I am not able to figure out. All I want is a realistic copy dialogue Timeout on a function call I'm calling a function in Python which I know may stall and force me to restart the script.   How do I call the function or what do I wrap it in so that if it takes longer than 5 seconds the script cancels it and does something else? How to change the "User License" type for customer portal users using a script? How to show that all points are inside of unit circle? There are $n$ points on the plane. Any $3$ of them are inside of a unit circle. How to show that all points are inside of unit circle?  It is needed to prove that if there is a unit circle for each $3$  points which contains them, there is also a unit circle which contains all $n$ points. Ubuntu 15.10 is not in Boot Manager I have a problem with Ubuntu 15.10  I have in my computer windows 10. Some days ago i decided to install Ubuntu in partition so i can have both in the same hard drive. The problem is that i cant get into ubuntu, i dont have the grub up so i always go to Windows in default mode. The only way to go into ubuntu is with the CD of installation, when im on the grub of the cd i press Esc, then i text exit in command lines and i go to a boot manager in which i can choose the ubuntu system. Its a strange think because it is the only way i can get into ubuntu, i will like to solve this problem. I try many tutorials already of solving this problem. I didnt get any solution so i will like to ask u before doing another tutorial. Thank u Frequency count of two column in R