What happens to Logistic Regression when the data is linearly separable? Will the estimates be unstable? How should I describe this scenario?
How to deal with perfect separation in logistic regression? If you have a variable which perfectly separates zeroes and ones in target variable, R will yield the following "perfect or quasi perfect separation" warning message:  Warning message: glm.fit: fitted probabilities numerically 0 or 1 occurred    We still get the model but the coefficient estimates are inflated.   How do you deal with this in practice?
Is there a symmetry associated to the conservation of information? Conservation of information seems to be a deep physical principle. For instance, Unitarity is a key concept in Quantum Mechanics and Quantum Field Theory.  We may wonder if there is an underlying symmetry, in some space, which may explain this conservation of information. I am trying to copy multiple files named "F3.bam" two level of directories to up and then rename these files with the name of the sub-directory after copy.  For example:  /samples/mydata1/RUN1/ID_date/PCR2/TIME1/F3.bam /samples/mydata2/RUN1/ID2_date4/PCR2/TIME7/F3.bam /samples/mydataxxx/RUN1/IDxxx_datexxx/PCR2/TIMExxx/F3.bam   Expected results:  1. The files are first copied two directories level up:  /samples/mydata1/RUN1/ID_date/F3.bam /samples/mydata2/RUN1/ID2_date4/F3.bam /samples/mydataxxx/RUN1/IDxxx_datexxx/F3.bam   2. The files are renamed according to the name of the current sub-directory:  /samples/mydata1/RUN1/ID_date/ID_date_F3.bam /samples/mydata2/RUN1/ID2_date4/ID2_date4_F3.bam /samples/mydataxxx/RUN1/IDxxx_datexxx/IDxxx_datexxx_F3.bam   Ideally a bash loop would be great (working on a Mac). Integral of $\frac{\sqrt{x^2+1}}{x}$ So I have to do the integration of $\frac{\sqrt{x^2+1}}{x}$. Give me a hint. What should I replace? Should I do it with integration by parts? Mac App Store: Downloads just don't start (Mojave) I want to download apps in the Mac App Store and the apps won't start to download. As you can see in the pictures below, the spinner starts spinning but nothing gets downloaded, the download simply doesn't start. I am logged in with my account. I tried logging out of the App Store and logging in again, restarting the Mac etc, nothing helped.  This is a relatively fresh installation of Mojave 10.14. Before with High Sierra 10.13 everything worked fine. It's a Late 2013 MacBook Pro 13". Installations are allowed from App Store and identified developers.   Some screenshots from Console output below. I have video tutorials that I want to show in my presentation with beamer class. I don't want the video files get embedded to the PDF because they will make the PDF size very very huge.  If you know how the videos can be played on the HTML with a reference rather than embedding the video file to the HTML file, I want something like this to be applied to my PDF presentation. I just want to reference the video URL from my PDF presentation.   Shortly speaking, can we use media9 to show a video on a PDF but the video is not embedded to the PDF?  Uploading those videos to a web server might be difficult for me because internet connection is very slow and sometimes not available in the presentation room. :-) Where are the pristine, untouched contents of a ~/.profile file? SQL Server default collation vs database with different collation - potential problems? I'm struggling with the design of new database that has to use a different collation (Y Collation) than the SQL Server Instance default collation (X Collation). I'm looking for potential problems.  Temp Tables by default will be created with X Collation so any joins on text data types will fail unless I create temp table with Y collations on columns.  What about SQL Server string functions: REPLACE, SUBSTRING, etc.? Will they always be returned in X collation? What about when I use REPLACE(...) COLLATE Y? Do you see any potential data loss or maybe any different problems? A woman's butt was allegedly touched by a man several times during a commute on the MRT.   How to use butt, bottom, buttock and ass? I am confusing with these words. Close and flag links do nothing on mobile site This morning (it's about six AM here) I find that I can no longer submit close votes; the link just jumps to the beginning of the page.  I'm on iOS, using a third-party browser called Grazing, but a brief check with Mobile Safari shows the same problem there.   Here on Meta, where my score is much lower, I only get a "delete" link on my own question, and that works fine. (Oops :-))   Update: As per comments, this affects the "flag" link, too, which doesn't even scroll to the top of the page. Update 2: Latest comment suggests this affects Android, too. Update 3: This also affects desktop computers when viewing mobile (when you click "mobile" in the footer) Update 4:  mentions Windows 8, too; simply deleting platform-specific tags 8 AWG solid EGC in raceway for 100 amp subpanel I'm adding a 100 amp subpanel to my detached garage and have a question about the EGC I've already pulled through the underground LFNC-B raceway. Taking the advice from a similar post on this forum, I decided to use a 8 AWG bare solid copper conductor for my EGC in the underground raceway back to the main house. The other 3 conductors are 3 AWG THWN-2 stranded copper. I did double check the NEC tables to ensure these were appropriately sized for the underground feed portion of my run and ensured the conduit fill was less than 40%. What I failed to realize though (until after I won the good battle of pulling this set though the raceway) was that there is a section in the NEC that prohibits the use of solid conductors 8 AWG or larger in raceways: &quot;310.3 Stranded Conductors. Where installed in raceways, conductors of size 8 AWG and larger shall be stranded.&quot; Dangit! Now I'm questioning why I didn't just use insulated green THWN-2 - it would have made my pull much easier! Rookie mistake. So how bad have I goofed up here? Let's say the inspector fails to call this out. Is this a safety issue? What's the rationale for the rule anyways? To prevent numskulls like myself from trying to pull larger gauge solid wire through a raceway and possibly damaging the other conductors? Or is there more to it? Interestingly, there seem to be several exceptions in the NEC that do allow for using 8 AWG solid EGC in raceways (690.46 for Array Equipment Grounding Conductors for example). I'm just trying to get a feel for the severity of this goof-up and if it's worth fixing if not required by the inspector. Any feedback from the experts would be much appreciated! List the files accessed by a program As I navigate through physics stackexchange, I noticed .  Electrons radiate light when revolving around nucleus? Why is it so obvious?  Note that I do not know anything about quantum mechanics - and I just want classical stories. android - out of memory exception when creating bitmap Generating hatched filling using Region functionality I'm having a really, really hard time figuring out how to install mods on Minecraft. I've looked everywhere I can think of for help but the information is almost always outdated or unhelpful.  I've seen on several sites about the use of something called Forge. The Mod I want to use requires 1.6.4 Forge and I have both Forge and the Mod folders sitting in my downloads folder.  I haven't installed any kind of mods for any game prior to this and I have little clue to the technical side of Minecraft, so please keep this in mind when you give me an answer please!  Things that might help you figure out how to help me:   I want to play this mod  and am using the 1.6.4 Forge given on a link that website gives Importing 3D DXF file into QGIS with z information as attribute value? HDD SMART interpretation - Possible impending drive failure I've just had an issue pop up related to my drives.  First things first, I was working in my case when I clumsily shifted the foot of the case off of my desk. Case shifted and hit the desk somewhat hard, but only fell an inch or two. It had been properly shut down so this may not have anything to do with the issue.  After booting up, I noticed that when playing a video from my F: Drive (Seagate), it produced a whine, almost a chirping sound coming from the hard drive bay. I think I may have heard this before the drop, but quieter.  Fearing impending failure I downloaded GSmartControl and inspected the drive information. The Seagate drive displayed a high Raw Read Error Rate, as well as a high Seek Error Rate.  I've read some of these values can be high on Seagate drives from the start. This drive is about 6 months old and the producer of the noise.  I also checked my Toshiba drive, which came with a refurbished prebuilt I bought about a year ago. It showed more normal SMART data, but displayed some concerning statistics (2 "Mechanical Start Failures" and 2 "Reported Uncorrectable Errors").  Both of the drives passed the basic SMART test, but the noise was quite alarming. It would stop as soon as a paused the video and start right up again as soon as I resumed playing.  Here is an album with 3 photos of the SMART data, the Seagate did not display statistics.  Could I please have help interpreting the SMART data, and whether this may indicate an impending failure?   Thank you for your time.   Here are images of the SMART data. Minimum value of $\left(a+\frac{1}{b}\right)^2+\left(b+\frac{1}{c}\right)^2+\left(c+\frac{1}{a}\right)^2$ Given $a,b,c \in \mathbb{R^+}$ such that $a+b+c=12$   Find Minimum value of $$S=\left(a+\frac{1}{b}\right)^2+\left(b+\frac{1}{c}\right)^2+\left(c+\frac{1}{a}\right)^2$$  My Try: By Cauchy Schwarz Inequality we have  $$\left(a+\frac{1}{b}\right)+\left(b+\frac{1}{c}\right)+\left(c+\frac{1}{a}\right)\le \sqrt{3}\sqrt{S}$$  $\implies$  $$\sqrt{3S} \ge 12+\frac{1}{a}+\frac{1}{b}+\frac{1}{c}$$  Now by $AM \ge HM $ inequality we have  $$\frac{a+b+c}{3} \ge \frac{3}{\frac{1}{a}+\frac{1}{b}+\frac{1}{c}}$$ $\implies$  $$\frac{1}{a}+\frac{1}{b}+\frac{1}{c} \ge \frac{3}{4}$$  hence  $$\sqrt{3S} \ge 12+\frac{3}{4}=\frac{51}{4}$$  hence  $$3S \ge \frac{2601}{16}$$  so $$S \ge \frac{867}{16}$$  is this approach correct and any better approach please share. In a finite cyclic group, the generator has the order of the group Let $G$ be a finite cyclic group of order $n$ generated by an element $g$. I want to show that the order of $g$ is exactly the order of $G$.   My try:   We can write $G=\{g^i\;|\;i\in \mathbb Z\}$. Since $G$ is finite, we know that there will be identifications $g^i=g^j$ that will make $G$ finite. By the multiplication law on $G$ we must have $g^0=1$. Also if $i&lt;j$ and if $g^i=g^j$ then $g^{j-i}=1$. I can see all these but not see why $g^n=1$ and not $g^k=1$ for all $0&lt;k&lt;n$? Thank your for your help!! I am trying to burn a shapefile to a raster using GDAL's RasterizeLayer. I pre-create an area of interest raster from a different shapefile, given a specific pixel size. This AOI then serves as a base for all following rasterizations (same number of collumns and rows, same projection and geotransform).  The issue occurs, however, when I go to burn the shapes to their own raster, based on the same pixel size and projections. The link below (don't have enough rep to post the image), shows the original shapefile in tan, and the dark pink where RasterizeLayer has burned data. The light pink is nodata values for the dark pink raster data. The grey is the AOI based on which the shapefile burn was completed.  Given the extents of the shapefile polygons, I would expect to see burn values in the bottom two corners, as well as the two pixels underneath the data that does show. Obviously, however, this is not the case.    As follows is the code that I used to generate these. All of the shapes were created using QGIS, and were all created in the same projection.  (It should be noted that the gridding in the picture shown was just to give an idea of the pixel size I was using.)  from osgeo import ogr from osgeo import gdal  aoi_uri = 'AOI_Raster.tif' aoi_raster = gdal.Open(aoi_uri)  def new_raster_from_base(base, outputURI, format, nodata, datatype):      cols = base.RasterXSize     rows = base.RasterYSize     projection = base.GetProjection()     geotransform = base.GetGeoTransform()     bands = base.RasterCount      driver = gdal.GetDriverByName(format)      new_raster = driver.Create(str(outputURI), cols, rows, bands, datatype)     new_raster.SetProjection(projection)     new_raster.SetGeoTransform(geotransform)      for i in range(bands):         new_raster.GetRasterBand(i + 1).SetNoDataValue(nodata)         new_raster.GetRasterBand(i + 1).Fill(nodata)      return new_raster  shape_uri = 'activity_3.shp' shape_datasource = ogr.Open(shape_uri) shape_layer = shape_datasource.GetLayer()  raster_out = 'new_raster.tif'  raster_dataset = new_raster_from_base(aoi_raster, raster_out, 'GTiff',                                 -1, gdal.GDT_Int32) band = raster_dataset.GetRasterBand(1) nodata = band.GetNoDataValue()  band.Fill(nodata)  gdal.RasterizeLayer(raster_dataset, [1], shape_layer, burn_values=[1])   Is this a bug in GDAL, or is RasterizeLayer burning data based on something other than just the presence or lack of a polygon within a specified pixel area?  The files that I was using can be found .