I am completely new to machine learning. I am working on my undergrad thesis that tries to predict how satisfied a person will be in a specific area by using linear regression. Since this study contains human behavior, ie different person's satisfaction level will be different in the same area, even if their demographics are the same, the dataset contains a lot of noise. The range of the dependent variable (Satisfaction) is 1-5. What can I consider as a good value of RMSE here? Currently the value is 1.08 but it changes if I divide my dataset based on some demographic, ie their jobs or gender, but the value is always more than 1
I have built a forecasting model for a company. Since it is dedicated to practical usage, I prefer to use the relative error parameter (like MAPE, SMAPE, &amp; MASE) as a measurement for my model performance and display it on the dashboard (the percentage error is easier to understand by user). I found an interesting reference about the criteria of a good forecast result based on MAPE from Lewis (1982):  ...but in my case, I can't use MAPE for some dataset because there is some zero actual demand so it can't be used as denominator in MAPE. So, I use SMAPE &amp; MASE instead, but I can't find any good references about good forecast result criteria based on SMAPE &amp; MASE, nothing like above. So, I'd really appreciate any help/suggestion about it :), Thank You! Reference: Lewis, C. D., 1982. Industrial and Business Forecasting Methods. London: Butterworths.
Is there a way to see how the markup of a per-site meta answer is formed? I sometimes see a useful markup feature in a per-site meta answer. However, I cannot edit it to see how one did it, since editing (or suggesting edits) is disabled for users with less than 2k reputation on per-site metas.  Is there a way to see the source code of a per-site meta answer? New passport and entrance Schengen I am from Brazil and travel a lot in Schengen countries. Under the rules of Schengen visa (3 months stay in a 6 months period). In my passport are the entrance and exit stamps, also to chec the days I stay in Schengen.  I need a new passport and will get this in Brazil. So in this new passport are NOT the stamps. Does this mean I start new with the Schengen visa rule? I seems like. The new passport is empty. Or do I miss something? It would be great because I am almost on my 90 days stay in the period of 180 days. How many MB/sec can I expect copying to USB 3.0 enclosure with SATA drive? We know that if a finite field $F$ has characteristic $p$ (prime), then $F$ has cardinality $p^r$ where $r = [F:\mathbb{F}_p]$.   I'm now trying to say something about the possible cardinalities of subfields of $F$. I can see that there is a subfield of cardinality $p^s$ for each $s$ that divides $r$, given by the fixed field of the group generated by $\phi^s$, where $\phi$ is the Frobenius automorphism.  Now suppose $K$ is a subfield of $F$. Then (since both are additive groups), Lagrange gives us that $|K|$ divides $|F|$, so $|K| = p^t$ for some $1 \leq t \leq r $ (alternatively, $K$ contains $\mathbb{F}_p$ and so is a vector space over $\mathbb{F}_p$ and is thus isomorphic to $\mathbb{F}_p^t$, where $t = [K:\mathbb{F}_p]$). By considering the multiplicative group of units of $K$ and $F$ respectively, we get that $ p^t - 1$ divides $p^r -1$. I want to make the leap to $t|r$, but I'm failing to see why this needs to be true. Any help would be appreciated. I have downloaded and installed the newest  for my Windows 7 (64-bit OS), but when I want to install 64-bit Linux, the New->Create Virtual Machine only displays 32-bit option, no 64-bit option. Could anyone give any clues about this issue? Thanks very much in advance! Why are mutable structs “evil”? Following the discussions here on SO I already read several times the remark that mutable structs are “evil” (like in the answer to this ).  What's the actual problem with mutability and structs in C#? Variation of Pythagorean triplets: $x^2+y^2 = z^3$ I have two JSON objects with the same structure and I want to concat them together using Javascript. Is there an easy way to do this? Show that the locus formed by z in the equation $z^3 + iz = 1$  never crosses the co-ordinate axes in the Argand plane. Further show that $$|z| = \sqrt{\dfrac{-\Im(z)}{2\Re(z)\Im(z) +1}}$$  Concept: $z=x+iy$ $z^3=(x+iy)^3=x^3-3xy^2+i(3x^2y-y^3)$ $iz=-y+ix$ Combined equation is $x^3-3xy^2-y-1+i(3x^2y-y^3+x)=0$ How do we proceed from here onward? I shall come, not will Native speakers, how can you comment such a sentence:  I shall come, not will  Can I use it for  I will definitely come, not maybe    Adding some information other people asked me about.  How I came to such a question.  Here   I asked about "Shall I win?" pointing that it could have some variants of understanding:  1) Shall I win? = Should I win? (suggestion)  2) Shall I win? = Will I win? (archaic with 1st person)  3) Shall I win? = is it 100% that I will win? (predestination\inevitability)  The excellent guy Mixolydian said either variant was possible, that it didn't matter what person you used "shall" with, it could have this "predestination\inevitability" anyway. Out of this we're getting that nowadays we can use "will" for simple future actions and "shall" for almost predicted (almost 100% surety of happening) future actions.  If I want to say to someone:  Don't be afraid, I will come anyway.  Don't get panicked, I will definitely come  Be sure, I will come in any case  I can use "shall" for it meanining an action into which I will put 100% effort:  I shall come!  And what if my original sentence is  Don't doubt, I will definitely come, not maybe or probably  Can I use  I shall come, not will  pointing that "shall" guarantees me putting all my strengths into it while "will" doesn't give any assuarance that I will do everything to finally come.  As I understood, it wasn't very easy to ask such a question because English was different everywhere - US, UK, Australie, Ireland etc. I heard it was acceptabse to use even "thee\thou" in Ireland or somewhere like that while all other world has already forgotten such words...  P.S. What I got from the answers ias that it was better to forget about the existence of "shall" cause it created so many misunderstandings:D Most of us have heard of Einstein's amazing equations which describe the universe around us, yet only some of us understand what the equations are actually saying.      What are these equations actually saying, and is there a simple (relatively) way to derive them?   Here they are, from :  $$R_{\mu\nu}-\dfrac{1}{2}g_{\mu\nu}R+g_{\mu\nu}\Lambda=\dfrac{8\pi G}{c^4}T_{\mu\nu}$$  I have a vague notion of what a tensor is (it describes things as an array and higher orders define more complex transformations), but I don't understand what all of these tensors are doing. And why is there a $c^{4}$  in the equation!? Gosper's unusual formula connecting $e$ and $\pi$ Getting a vector into a function that expects a vector It didn't fixed the error. So, how do I fix my GUI update?  For every software I have to install it from command line because I got same error when install software from Ubuntu Software Center. What does the comma operator do? Is it true or false that $\lvert P([0, 1]) \setminus P((0, 1)) \rvert > \lvert P(\mathbb{N}) \rvert$ Is it true or false that $\lvert P([0, 1]) \setminus P((0, 1)) \rvert &gt; \lvert P(\mathbb{N}) \rvert$ ?  I need a hint because I don't see a way to solve this How can I cast artificially darker shadows? I want to make certain shadows more prominent (using Cycles) without further illuminating the rest of the scene.  Example: I have a simple studio with a bowl of fruit and 3-point lighting.  The light looks great so I don't want to change it but I want the bowl to cast a darker shadow on the ground (without dimming the back-light).  Alternatively, and this would be really cool, an anti-light source.  Like a spot light that throws darkness instead of light. (Am I crazy for wanting this?)  Thanks! A $60\times 60$ board is partitioned into rectangles of size $2\times 5$ (or $5\times 2$). Is it true that there always exist another partition into rectangles of size $1\times 3$ (or $3\times 1$) such that any $2\times 5$ (or $5\times 2$) rectangle contains a $1\times 3$ (or $3\times 1)$ rectangle?  For the "simple" partition into $2\times 5$ rectangles, this is certainly true: use the simple partition into $1\times 3$ rectangle.  Another way to partition is to first partition the $60\times 60$ board into $12\times 10$ boards, and then for each such board, put two $2\times 5$ at the top and ten $5\times 2$ below. It is not hard to tile each such $12\times 10$ board with $1\times 3$ (or $3\times 1)$ rectangles so that each $2\times 5$ (or $5\times 2$) contains a $1\times 3$ (or $3\times 1)$ rectangle.  (I'm assuming that an $m\times n$ rectangle has $m$ rows and $n$ columns.) “...than I am” vs. “...than me” I read an English grammar article in which the author talked about the correct use of pronouns.  He writes:     If the extended sentence is “She’s more likely to ask him than I am,” in which the comparison is between the subject and the writer, I is correct. However, if the intent is to convey that the man referred to as him is more likely to be asked something by the subject than the writer is, the correct pronoun form is me, but that distinction should be clarified with a revision like “She’s more likely to ask him than ask me.”   Before reading this piece, I thought that the two sentences had the same meaning. While the second example is quite clear for me (“She’s more likely to ask him than ask me”), I don't think that I have correctly understood the first one. Could anyone explain it to me, please? HTML table headers always visible at top of window when viewing a large table