In statistics class, we are often taught that the advantage of ANOVA is that it can control for the type 1 error rate (the type 1 error rate will be inflated if we run many groupwise t-tests). The typical procedure for testing whether the means of several groups are different is:        ANOVA   If ANOVA produces significant results, run pairwise t-tests with Bonferroni adjustment      However, if that is the case, can I skip the ANOVA part altogether? With the Bonferroni adjustment, the type 1 error is under control. Then is there other benefits of using ANOVA?
I have an experiment where I measure the effect of a manipulation on two different groups of participants, and the variable that I manipulate also has two levels. Thus, I can essentially use a 2x2 ANOVA to analyze the results. But it is also possible for me to measure the effect of the different levels of the variable first on Group 1 and then on Group 2, by using paired-samples t-tests.   Is there a rule of thumb to decide what needs to be done in this case? I think one advantage of using an ANOVA could be the option to investigate the interaction between the different groups and the different levels of the variable. Perhaps one could also argue that an omnibus analysis is also a better choice from a stylistic point of view.   But is there a very compelling conceptual reason to prefer a 2x2 ANOVA over two separate pairwise comparisons in my case? And if so, what would it be?
How to run Unix shell script from Java code? It is quite simple to run a Unix command from Java.   Runtime.getRuntime().exec(myCommand);   But is it possible to run a Unix shell script from Java code? If yes, would it be a good practice to run a shell script from within Java code? What is the magnetic field inside hollow ball of magnets? Setup: we have a large number of thin magnets shaped such that we can place them side by side and eventually form a hollow ball. The ball we construct will have the north poles of all of the magnets pointing toward the center of the ball, and the south poles pointing away from the center. The magnets in this case are physically formed such that in this hollow ball arrangement they are space filling and there are no gaps between them.  Is such as construction possible? If so, what is the magnetic field (B-field) inside and outside the ball? Pseudo-terminal message in script When does decision tree perform better than the neural network? Factorial Inequality problem $\left(\frac n2\right)^n > n! > \left(\frac n3\right)^n$ I met an inequality, I ask, do not mathematical induction to prove that:     Prove \[ \left(\frac n2\right)^n > n! > \left(\frac n3\right)^n \] without using induction Prove inequality $n<3^n$ using mathematical induction Prove that $n&lt;3^n$ where $n \in \mathbb N$,  when $ n=1 $, I have proved it's true. And assumed when $n = p$ , $p&lt;3^p$ is true. Can any body help me in showing that it is true for $n =p+1$ I have a bunch of external and internal HDDs that I use on a Linux system. I only have Linux systems, so using a Linux file-system would only make sense, right? However I'm currently using NTFS everywhere, because it gives me the most usable space out of HDDs.  I would like to switch to Linux file-systems now though, mostly because of permissions and compability (e.g. I can't get my LUKS encrypted NTFS partition to resize under Linux, keeps telling me to chkdsk under Windows).  However when I formatted those HDDs I tried out a bunch of different filesystems and every Linux filesystem, even ext2 which as far as I know has no journaling, used a lot of space for itself. I don't recall exact values, but it was over 100GB that NTFS got me more on a 2TB HDD, which is a lot.  So my question is: Is there a way to make ext-filesystems use less space for themselves? Or is there another filesystem (I've tried ext2, ext3, ext4, NTFS and vfat - None of them came even close to the usable space NTFS offered me) with perfect Linux support and great usable space?  I'd love to hear about how and why filesystems (especially ext2 which has no journaling) use that much more space than NTFS and I don't know where else to ask. I'd mostly prefer a way to use ext4 without journaling and anything else that uses up this much space, if that's possible. I add js file with drupal_add_js in hook_form_alter, it is ok and I see it in list of js loaded in page, but when I submit form and form not validate and return to that form (after validation failed) I don't see js files that added to form, why this happened? and how can add my js file in that form after validation failed ?   some part of my code   function mymodle_form_alter(&amp;$form, $form_state, $form_id) {   if ($form_id == 'news_node_form') {     drupal_add_js(drupal_get_path('module', 'mymodule') . '/js/mymodulejsfile.js'); //, array('scope' =&gt; 'footer','weight' =&gt; 10));   } }   code work correctly in add and edit form, but when form submit and validation failed it show validation error but my js file not loaded in page (I checked html source and check firebug script files), but there is not my js file, Meta sites in "Your Communities" display different reputation While using the top bar to navigate across communities, I noticed that the reputation displayed on meta sites on that list does not match the one of their corresponding main sites:    I have noticed on past situations that reputation gained takes a bit to "update" on the display on Meta sites (that is, if you gain rep on SO, for example, it will take some time for you to see your updated rep on MSO).  However, I have never noticed this behavior here, on the Sites List of the top bar. Furthermore, the "delay" here seems to be more severe, as the "outdated" rep showed is of several days ago (for example, I turned 3k on SO almost exactly a week ago, but the rep shown on MSO is still &lt;3k).  Any idea what could be causing this behavior?    Update: 2 months later this persists: my main site rep updates correctly but their corresponding meta rep remains the same as in the image above.     Update: As per Catija's  I removed the site (MSO) and put it back in, but it didn't update the rep.   However, after removing one site (TWP Meta), waiting at least a day, and then adding it back I see that although the reputations still don't match, the number displayed did changed a bit (previously 29,924 but now 33,112): Why wasn't Restricted Section of the library better protected? How do I backup data (SMS/contacts) from a device with a broken screen? I just broke the screen of my (unrooted) Galaxy S.  How do I get back my SMS and contacts?   PS: I tried Kies but it won't detect my phone for some reason. (Kies works fine with another Galaxy I possess but not this one) How do you keep parents of floated elements from collapsing? From the third week ( when does it actually begin) This describes a certain natural process that takes 15 weeks  It describes what a certain component looks like at some point in time during a naturallly occurring process  What I don't get is if it means it appears this way starting in the third week or after ?  Here's the full sentence  "The malleus first appears as a cartilage model from the third week"  Thanks again for you support guys How many ways can $r$ nonconsecutive integers be chosen from the first $n$ integers? It would seem that far-away stars are at such a distance that I should be able to take a step to the side and not have the star's photons hit my eye. How do stars release so many photons to fill in such great angular distances? Prove that $\operatorname{trace}(A) = 0$ if and only if $A^2 = 0$. Close popup doesn't appear after editing the question without refreshing the page Seems like a bug:  The user:   Edits a question Then, he decide to close it. Clicks on the Close button. The popup doesn't appear. Refreshes the page. Click on the close button. The popup appears.   After editing in the link appears a hash: #. But I don't think that this is the problem because if I add the hash without editing the close popup appears.  It's minor, but I think that is good to be reported and solved.  Edit: The close popup doesn't open after we click an edit has been made to this post; click to load. I'm confused with using single or double brackets. Look at this code:  dir="/home/mazimi/VirtualBox VMs"  if [[ -d ${dir} ]]; then     echo "yep" fi   It works perfectly although the string contains a space. But when I change it to single bracket:  dir="/home/mazimi/VirtualBox VMs"  if [ -d ${dir} ]; then     echo "yep" fi   It says:  ./script.sh: line 5: [: /home/mazimi/VirtualBox: binary operator expected   When I change it to:  dir="/home/mazimi/VirtualBox VMs"  if [ -d "${dir}" ]; then     echo "yep" fi   It works fine. Can someone explain what is happening? When should I assign double quotes around variables like "${var}" to prevent problems caused by spaces? There's a way to safely try KDE on top of an Ubuntu installation, keeping the possibility to revert the changes in case I dislike how it runs? Meaning of probability notations $P(z;d,w)$ and $P(z|d,w)$ What is the difference in meaning between the notation $P(z;d,w)$ and $P(z|d,w)$ which are commonly used in many books and papers?