I have same error message as in this . However all my coefficients look normal with no inflated value or standard errors. My question is how can I make sure the error message is a sign of perfect separation or it's just some of my observations have extreme predicted probabilities?  Also, my model has Residual deviance=Inf and AIC=Inf, would they suggest that there is no perfect separation as they are measures of goodness of fit?
Why is it that logistic regression becomes unstable when classes are well-separated? What does well-separated classes mean? I would really appreciate if someone can explain with an example.
I have a query which selects a max value over all the values of in a datetime column (dtimesent).  select dtimesent, max(ResponseTime) AS maxtime FROM allrequests  where Request like '%Requestsa%' group by dtimesent   I need to get the value of the request colmn for each max response time in each group by. Is there any easy way to do this?  There can be multiple rows per dtimesent value so I can't just include the request column in the group by,  Many thanks, On which Stack Exchange site should I post subjective questions? How to setup dual-screen monitors in xorg.conf using Nvidia TwinView? Output of which command used for input to cd I would like to take the output of a which command, and cd to the parent directory. For example, say I have the following:  which someprogram   With output:  /home/me/somedirectory/someprogram   And I would like to cd to the directory that someprogram lives in:  cd /home/me/somedirectory   I'd like to accomplish this in one line. What is the most elegant, tricky, short way to do this? I am a bit confused. When can we omit the preposition on before weekdays? (Monday, Tuesday etc.) Sometimes I read weekdays without the preposition on. If the preposition is left out, does it work the same way, or does it change the meaning?  Example without the preposition     The UGC issued the public notice Monday after its two previous orders   in this regard were overlooked by the DU.   Example with the preposition     The commission on Monday also issued a public notice against the FYUP   in all leading newspapers for parents and students. Why not to extend the set of natural numbers to make it closed under division by zero? We add negative numbers and zero to natural sequence to make it closed under subtraction, the same thing happens with division (rational numbers) and root of -1 (complex numbers).  Why this trick isn't performed with division by zero? How should I implement hook_menu()? We were given the following problem as an assignment, we proved the converse in class for prime numbers; however, we can't use the assumption that $\operatorname{gcd}(a,b) = 1$.  So I am struggling to think of my first possible move.  We are given $ar + bs = 1$, the only think I can think of is let $d$ be a common divisor or $ar + bs$ and then show that the $d = 1$.  However, I am not really sure how to do that.  If anyone could just give me a hint or two to nudge me in the right direction I would be appreciative. ubi-partman failed with exit code 10 - ubuntu 18.04 I'm trying to install Ubuntu 18.04 on my laptop. After choosing the partitionn i have the following error message: grub-efi-amd64-signed package failed to install into / target/.    Then I tried to install via "try ubuntu" and i get:  ubi-partman failed with exit code 10     What should I do? Find the limit of $\lim\limits_{(x,y)\to (0,0)} \frac{x^2y^2}{x^2y^2+(x-y)^2}$ Is it OK to use a forward slash '/' between words other than the obvious 'and/or'? I don't want to get into the proper use of the phrase 'and/or', but rather to investigate the use of the forward slash between other words. Examples:   I have an interview with him/her this afternoon. He has a large binder/notebook.   And even separating just letters:   I connected the i/o ports. (input/ouput) Mark the field as n/a. (not applicable) I did it w/o her help. (without)   It seems as thought the forward slash can be used to indicate an option, display ambiguity, shorten 2 words and shorten 1 word (and others).  Is it OK to use a slash to separate these words/letters (yes, that was intended), or is it better to explicitly say 'his or her'? One more thing, is it correct to 'chain' these phrases together? I'm horrible with examples but here's one:   I don't open letters/mail that aren't/isn't addressed to me. A piecewise $C^1$ curve has Jordan measure zero. $\newcommand{\Reals}{\mathbb{R}}\gamma:[0,1]\to \Reals^2$ is an injective parametrization of a curve $\Gamma$, which is piecewise $C^1$ and the length of the curve is $L(\Gamma_k)&lt;\infty$.   1.1.: Show that for every $n\in N$ there is a decomposition $0=t_0&lt;t_1&lt; \dots &lt;t_n=1$ of $[0,1]$ so that $L(\Gamma_k) = \frac{L}{n}$ for $k=1,\dots ,n$ and $\Gamma_k=\operatorname{Im}(\gamma_k)$, $\gamma_k=\gamma|_{[t_{k-1},t_k]}$.   1.2.: Show that you can cover $\Gamma$ with a system of spheres of radius $\frac{L}{n}$.   1.3.: Use 1.2. and 1.3. to show that $\Gamma$ has Jordan measure zero.   I wasn't there when they discussed when a function has Jordan measure zero  and how those things correlate with this exercise so if someone could give me some hints that would be great. How is it like to live in Helsinki?  What is it like to live in Helsinki?  How is living in Helsinki?  What are the differences between these three sentences and what is the common way to ask someone for their opinion about the city they live in? Formula for prime counting function I saw this formula on  page 2  $$\pi (n)=\sum_{j=2}^{n}\frac{\sin^{2}\left(\pi \frac{(j-1)!^{2}}{j}\right)}{\sin^{2}(\frac{\pi }{j})}$$  Where $\pi(n)$ is the prime counting function. Is this true? How to prove it? What is involved in converting a PC video card to have boot screen on the Mac? I've got a PC video card that I'd like to get boot screen support for on my Mac Pro. In particular, it is a Gigabyte R9 270X. The card is supported on the Mac once it boots, but I would like to get boot screen back since my old 8800GT has been baked in the oven a few too many times by now :-)  I've seen numerous guides on the internet about flashing the BIOS on the video cards and also ones that speak about adding the EFI BIOS, but in the haphazard forum approach, it isn't clear how this all works. To some degree, I've recently come away with the notion that you don't get rid of the existing BIOS, but rather add an EFI partition to it that the Mac would recognize. If that assumption is correct, then it would lead me to believe that adding an EFI BIOS that works on a similar card (R9 280X or 7950 which are both close but not quite) should work since I'm assuming that the existing BIOS would be similar enough to hook in. Failing that, I'm not clear how you would get a card-specific EFI BIOS for boot screen support.  Anyone an expert on this? I'm just really having a hard time trying to sift through all this and hoping to get a more direct answer! how do you make clothes move along with your model? Do you rig the model first and then parent it to the body of the character then click cloth simulation? I am a little bit confused with the process. Thanks for the help. What is the difference of 3 object declarations of javascript I've just updated to macOS 10.12 and when I try to execute srm in Terminal, it says -bash: srm: command not found.   Is srm removed? How to fix this? I have an older iPod touch which which supports up to iOS 6.1.6 and nothing newer.  This device is equipped with a Linea Pro barcode scanner and previously had an application called "" installed.  Recently I was attempting to do some work on a web application I wrote and realized that I needed to update to a newer version of Web Barcode - but unfortunately the Apple ID saved on my device was deactivated a few years ago.  So I went to settings and updated it with my current Apple ID.  Then again tried to update the App from the Apple store.  Still no dice - it was asking me for the password on the old account.  So then I figured I'd just remove it and reinstall from scratch.  Deleted the app and went to the store but now I am met with a message that the new version requires at least iOS 8.0.  I feel I followed a very logical series of steps to update this application and while I can understand that I won't be able to install the newest version, how can I get the old version back?  The device is completely useless without the barcode scanning application and the Apple store is now refusing to install any version at all on my device.  What can I do to get the original version of this application reinstalled? Someone asked me this question and I don't think I gave him an adequate answer (I was trying to think of the extreme case - that of neutron stars)