This question:    It seems perfectly reasonable, but then, I posed it.  It didn't have a lot of upvotes, and it has had no answers, but that doesn't make it invalid.  It got a downvote yesterday for no reason that I understand. Today, pfft.  What's the reason this happens?
Related to Meta Super User efforts:  and Meta Server Fault efforts:  We already auto-remove negatively voted unanswered old questions automatically after 30 days, network wide, with no human intervention required. I was thinking we might extend that to remove old, unanswered zero score questions... based on the following criteria:  fewer than (question age in days * 1.5) views 0 score or lower, or 1 score or lower if the original author is deleted no answers 1 comment or fewer asked more than 1 year ago (thus based on creation date, not last activity date, so , or a user editing it, does not give a doomed question 365 more days of zombie &quot;life&quot;)  See the results of this query on:  (10509) |  (787) |  (650) This query has been refined based on the comments, and this is the final version that will roll out tonight. Every site in the network (except metas) will automatically delete old questions that meet this criteria from this point forward.
Assumptions of linear models and what to do if the residuals are not normally distributed I am a little bit confused on what the assumptions of linear regression are. So far I checked whether:  all of the explanatory variables correlated linearly with the response variable. (This was the case) there was any collinearity among the explanatory variables. (there was little collinearity). the Cook's distances of the datapoints of my model are below 1 (this is the case, all distances are below 0.4, so no influence points). the residuals are normally distributed. (this may not be the case)  But I then read the following:  violations of normality often arise either because (a) the distributions of the dependent and/or independent variables are themselves significantly non-normal, and/or (b) the linearity assumption is violated.  Question 1 This makes it sound as if the independent and depend variables need to be normally distributed, but as far as I know this is not the case. My dependent variable as well as one of my independent variables are not normally distributed. Should they be? Question 2 My QQnormal plot of the residuals look like this:   That slightly differs from a normal distribution and the shapiro.test also rejects the null hypothesis that the residuals are from a normal distribution: &gt; shapiro.test(residuals(lmresult)) W = 0.9171, p-value = 3.618e-06  The residuals vs fitted values look like:   What can I do if my residuals are not normally distributed? Does it mean the linear model is entirely useless? How can one motivate the relativistic momentum? Motivating the non-relativistic momentum $$\mathbf{p} = m\mathbf{v}$$ is quite easy: it is meant to represent the quantity of motion of the particle, and since the mass is one measure of quantity of matter it should be proportional to mass (how much thing is moving) and should be proportional to velocity (how fast and to where it is moving). Now, in Special Relativity the momentum changes. The new quantity of motion becomes $$\mathbf{p} = \dfrac{m\mathbf{v}}{\sqrt{1-\dfrac{v^2}{c^2}}}$$ Or, using $\gamma$ the Lorentz factor $$\mathbf{p} = \gamma(v) m\mathbf{v}$$ where I write $\gamma(v)$ to indicate that the velocity is that of the particle relative to the frame in which the movement is being observed. The need for this new momentum is because the old one fails to be conserved and because using the old one in Newton's second law leads to a law which is not invariant under Lorentz transformations. So the need for a new momentum is perfectly well motivated. What I would like to know is how can one motivate that the correct choice for $\mathbf{p}$ is the $\gamma(v)m\mathbf{v}$. There are some arguments using the mass: considering a colision, requiring momentum to be conserved, transform the velocity and then find how mass should transform. Although this work, it doesn't seem natural, and it is derived in one particular example. On my book there's even something that Einstein wote saying that he didn't think it was a good idea to try transforming the mass from $m$ to $M = \gamma(v)m$, that it was better to simply keep $\gamma$ on the new momentum without trying to combine it with the mass. So I would like to know: without resorting to arguments based on transformation of the mass, how can one motivate the new form of momentum that works for special relativity? If I want to display the IP address that is assigned to eth1, how can I do this in Bash? Which method performs better: .Any() vs .Count() > 0? in the System.Linq namespace, we can now extend our  to have the  and  extension methods.  I was told recently that if i want to check that a collection contains 1 or more items inside it, I should use the .Any() extension method instead of the .Count() &gt; 0 extension method because the .Count() extension method has to iterate through all the items.  Secondly, some collections have a property (not an extension method) that is Count or Length. Would it be better to use those, instead of .Any() or .Count() ?  yea / nae ? Why do we say "try and" [verb] instead of "try to" [verb]? (E.g., "Try and call me tomorrow.") In written and standard semi-formal (and above) spoken English, one would use &quot;try to&quot;:  Try to be a better person. Try to get the fishhook out of my thumb, please. Try to find a pharmacy when you need one.  But in spoken English, we (Americans, at least) usually substitute &quot;try and&quot; for all those cases. &quot;Try to&quot; makes sense because the &quot;to&quot; begins the construction of an infinitive: &quot;try to be&quot;, &quot;try to do&quot;, &quot;try to act&quot; and so on. &quot;Try and&quot; on the other hand doesn't seem to make any sense. I'm curious how the &quot;try and&quot; crept in, and when. It's really tough to Google small words like these, so I'm not finding anything on the Web. Is it a contraction of something like &quot;Try hard, and ...&quot;? Note: I've seen  and it is somewhat related but doesn't tell me what I want to know. Edit Observe how, even on this site,  construction. Turning it on its head Note that you can't make a negative construction with &quot;try and&quot;:  It's raining. Try not to get wet. It's raining. Try not and get wet. [?]  Even adding do doesn't help. The following means something different from &quot;try not to get wet.&quot;  It's raining. Don't try and get wet.  Even use of to instead of and there means something else:  It's raining. Don't try to get wet.  &quot;Try not to get wet&quot; means try to stay dry. &quot;Don't try to get wet&quot; means avoid actively seeking out a soaking, and implies that a soaking might in fact be what you are looking for. MORE I just happened to notice a video from an editor for Merriam-Webster on this very topic, so I include the link here: . Double dispatch in C#? When Cantor's Intersection theorem won't work with closed sets Give an example to show that Cantor's Intersection Theorem would not be true if compact sets were replaced by closed sets.    Compact set is closed and bounded, so what I'm going to find is something that is closed but not bounded.  By the Cantor theorem, which says that a decreasing sequence of non-empty compact subset will have a non-empty intersection.  What I was trying to approach is how two sets just "touched" and as if they have not bounded, two sets "touched" nothing. But I cant give an example for that Problem with Winbind/Samba I am moving from Egypt to the Netherlands and I need to take my PC with me. I won't be taking the monitor, just the case, but I'm wondering what the best way would be.  Am considering taking it as carry-on because I'm allowed 8kg and at least then I can handle it myself. Has anyone done this before and can give me tips or warn me that this doesn't work? Would putting it in my normal suitcase as checked baggage be a better idea? SharePoint Migration 2007 to 2013 We're planning to upgrade an existing farm from 2007 to 2013. I learned that the best way and maybe the only way to achieve this is by migrating in two steps. 2007 to 2010 and 2010 to 2013. The actual farm is a sql-server(2008r2 64 bit) and a sperate sharepoint-server(web-frontend, etc....) I want to keep the sql-server as it is, if possible and we want to install a new 64bit host for sharepoint 2013. We will design a new branding for 2013 afterwards, so we need to keep the content, but not the layout. There's so much about migration available on the web, but Can I find something like best practises? What is the difference between Shrink Database and File? DBCC ShrinkDatabase() DBCC ShrinkFile()    Do I need to run both DBCC commands in order to shrink the database? What is the difference between these two above? Masking NetCDF time series data from shapefile using Python I have a 3-D time-series precipitation data (187 x 1800 x 3600), stored in a NetCDF file. I need to obtain the precipitation data for a shapefile. import matplotlib.pyplot as plt from netCDF4 import Dataset, num2date,  from matplotlib.pyplot import figure from datetime import datetime, date, timedelta import numpy as np import xarray as xr import pandas as pd import geopandas as gpd       MSWEP_monthly = 'D:\G3P\DATA\Models\MSWEP\MSWEP_monthly.nc4'  MSWEP_monthly = Dataset(MSWEP_monthly, 'r') Pre_MSWEP = MSWEP_monthly.variables['precipitation'][:]   MSWEP_monthly2 = xr.open_dataarray('D:\G3P\DATA\Models\MSWEP\MSWEP_monthly.nc4')  Lon_MSWEP = MSWEP_monthly2.lon Lat_MSWEP = MSWEP_monthly2.lat  Africa_Shape = gpd.read_file('D:\G3P\DATA\Shapefile\Africa_SHP\Africa.shp')    from osgeo import gdal,osr,ogr  def makeMask(lon,lat,res):     source_ds = ogr.Open(shapefile)     source_layer = source_ds.GetLayer()       # Create high res raster in memory     mem_ds = gdal.GetDriverByName('MEM').Create('', lon.size, lat.size, gdal.GDT_Byte)     mem_ds.SetGeoTransform((lon.min(), res, 0, lat.max(), 0, -res))     band = mem_ds.GetRasterBand(1)       # Rasterize shapefile to grid     gdal.RasterizeLayer(mem_ds, [1], source_layer, burn_values=[1])       # Get rasterized shapefile as numpy array     array = band.ReadAsArray()        mem_ds = None     band = None     return array  shapefile = 'D:\G3P\DATA\Shapefile\Africa_SHP\Africa.shp' source_ds = ogr.Open(shapefile)  # calculate the cellsize cellsize = Lon_MSWEP[:][1] - Lon_MSWEP[:][0]   # create the mask mask = makeMask(Lon_MSWEP,Lat_MSWEP,cellsize)  Now if I implement the following code, the precipitation data for the first day (from the time-series) can be obtained with shape of 1800x3600: precip = np.ma.masked_where(mask==0,Pre_MSWEP[0,:,:])  I tried to use a for loop to mask the precipitation data for the entire time series (time, lon, lat) over the area of interest. however, the below code gives me a 2-D data, probably for the last day. Why is that? for i in range(len(Pre_MSWEP)):     precip = np.ma.masked_where(mask==0,Pre_MSWEP[i,:,:]) What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits. Is it ethical to omit the PhD credential from my resume? I am applying for a Statistical Programmer position at a commercial research organization (CRO), and I am wondering if it is unethical to omit my PhD in Statistics from my resume?  All of my degrees (Bachelor's, Master's, PhD) are in Statistics, and I am just wondering if it would be ethical to just list my Bachelor's and Master's degree on my resume, and indicate my experience as a RA while I was a PhD student as my "work experience"? (Since this Statistical Programmer position only requires Master's degree plus some years of experience)  I am asking this question because I do not want to do anything unethical/cause me troubles later on. Can we model gravitation as a repulsive force? This question is actually related to my earlier question ("").  The fact that objects move a lot in the universe and that the universe is expanding, can imply that gravity is a repulsive force that increases with distance.. so the farthest objects repel us more.  This can still explain several existing observations, e.g., why does the apple fall?   Motion is the result of such repulsion. Two objects unlucky enough not to be moving relative to each other get squished due to the repulsion of the rest of the universe  around them. The earth repels the apple less than the stars so it is pushed towards the earth.   Furthermore, it can explain the expanding universe without the need for dark energy.  This could be demonstrated in a thought experiment. If we take a lot of same-charge particles (with small mass) such as electrons and lock them in a large box at a low enough temperature. The mutual repulsion of the particles may cause similar motion as if due to gravitational attraction.   Another experiment would be to measure the slight changes in our weight during day and night when the sun and earth align (if their masses are large enough to detect the feeble change in repulsion).   [EDIT: the question in the original form may not have been clear. It is "can we model".. with a yes/no answer and why (not). If downvoting, please justify. which of the following is NOT a possible value of $(e^{f})''(0)$?? Let $f$ be an analytic function on $\bar{𝐷} = \{z \in \mathbb{C}: |z| \le 1\}$. Assume that $|𝑓(𝑧)| ≤ 1$ for each $z\in \bar{D}$. Then, which of the following is NOT a possible value of $(e^{f})''(0)$??  $(A) 2$  $(B) 6$  $(C) \frac{7}{9}e^{\frac{1}{9}}$  $(D) √2 + 𝑖√2$  So I take a look at Cauchy Integral Formula and then $$(e^{f})''(0)=\frac{1}{\pi}\int_{|z|=1}\frac{e^{f(z)}}{z^3}$$  Taking modulus on both sides we have $$|(e^{f})''(0)| \le \frac{e}{\pi}2\pi=2e$$  Hence (b) cannot be the choice.   Is this alright!!  Thanks for the help! Why prefer the 18-55mm and 55-250mm lenses vs 18-200mm? If a person uses the wrong form of your or you're, would that be considered a spelling or grammatical error? I can really see it swinging both ways...  A sentence with the incorrect use of the word is technically grammatically incorrect, but the root cause could be simple spelling error. If a person speaks a sentence with an incorrect use of the word in question, it seems grammatically correct. When you look at the reader's script, it is then determined to be a spelling error.  When shown in writing, should the error be marked as a spelling or grammatical error? Seeking English term for relationship between two members of extended family? How to smooth shade an object while retaining hard edges? I frequently come to the problem of having a mesh with parts I would like to render smooth and "hard" edges connecting them.   How can I set the mesh to show the sharp edges but render everything else smooth?  In the example I would like the sides of the individual cylinders render smooth but the intersection between bottom and top to be sharp/flat