In R the princomp()and the factanal() are somewhat similar. At least their output looks pretty similar. I learned that this is not surprising since the print function of princomp comes from factanal. I understand that SS loadings do not make much sense for princomp as it is bounded to 1 anyway. Moreover, as Joris stated on nabble, the proportion of variance is only printed because of the common print function, but does not contain valuable information when princomp is used.   What I do not understand is rather not an R question but more a multivariate stats question what is the conceptual difference between these PCA and Factor Analysis functions as they are used in R? This question relates particularly to the scores (let's assume "regression" scores for FA) respectively the difference between scores in both concepts?  What should I rather use when I want to use to resulting scores in a regression model (for example in order to circumvent multicollinearity)? I also understand that PCA has a fixed number of components while FA has fewer factors than variables.   richiemorrisroe's answer in the thread suggested by Rob Hyndman might go into that direction.
It seems that a number of the statistical packages that I use wrap these two concepts together. However, I'm wondering if there are different assumptions or data 'formalities' that must be true to use one over the other. A real example would be incredibly useful.
Defining font color inside highlight fails Since I wanted a better readability of highlights of a would be black &amp; white-printed document, I needed to change both the highlighting color (gray) AND the font color (white).  Depending which command you implement inside the other will compile or not: \hl{\textcolor{white}{Fail}} does not work, compiling returns Package xcolor Error: Undefined color '{white}'.  Here's the mwe:  \documentclass{article} \usepackage{xcolor} \usepackage{color} \usepackage{soul} % Enables highlighting \sethlcolor{gray}  \begin{document}      \textcolor{white}{\hl{Success}}     %% Error:     %% Package xcolor Error: Undefined color `{white}'.     \hl{\textcolor{white}{Fail}}  \end{document}   So, in the end, the problem is sorta solved but I thought you might have an answer as to what happens. Applied modifiers are not visible Limit of $L^p$ norm Could someone help me prove that given a finite measure space $(X, \mathcal{M}, \sigma)$ and a measurable function $f:X\to\mathbb{R}$ in $L^\infty$ and some $L^q$, $\displaystyle\lim_{p\to\infty}\|f\|_p=\|f\|_\infty$?    I don't know where to start. Number of permutations of $n$ elements where no number $i$ is in position $i$ How can I force a line break in the table of contents? The optical density of a medium is quantified by its refractive index $n$. Does it have any correlation with the mass/number density of the medium? In other words is an optically denser medium must have a greater mass density compared to an optically rarer medium? Suppose $G$ is a group generated by elements $x$ and $y$ where $xy^2 = y^3x$ and $yx^3 = x^2y$ What can you prove about $G$? Suppose $G$ is a group generated by elements $x$ and $y$ where $xy^2 = y^3x$ and $yx^3 = x^2y$ What can you prove about $G$?  I've just been playing around with the relations but I can't seem to get anywhere. It seems as if I'm going in circles. I don't know what to look for in terms of how the equations should look in order to give me an insight into the structure of the group.  So given a group presentation, are there any general strategies of what to look for in the relations (as in how to rearrange them) in order to obtain insight about the group? Generating random numbers without repetitions how to calculate $$\int_0^\infty \frac{x^{3}}{e^{x}-1} \; dx$$   Be $q:= e^{z}-1 , p:= z^{3}$ , then $e^{z} = 1 $ if $z= 2\pi n i $, so the residue at 0 is : $$\frac{p(z_{0})}{q&#39;(z_{0})} = 2\pi i n ^{3}$$  problem is that this is not symmetric, so how does one find the definite integral? Comparing negatives: "she seems not to know" vs. "she doesn't seem to know" What is the difference in style and meaning between the following two:        She seems not to know.   She doesn't seem to know.      Is there a name to this type of construction? Let's say I write a mine.service file. Then I use systemctl enable mine.service.  If I later decide to edit mine.service, do I have to tell systemd that mine.service was changed? If so, how do I do that? Encouraging software publishers to use StackExchange as support mechanism $(function(){   $('.slider').mobilyslider({     content: '.sliderContent',     children: 'div',     transition: 'horizontal',     animationSpeed: 500,     autoplay: true,     autoplaySpeed: 9000,     pauseOnHover: true,     bullets: true,     arrows: true,     arrowsHide: true,     prev: 'prev',     next: 'next',     animationStart: function(){},     animationComplete: function(){}   });    });   I am integrating the above JavaScript file in a Drupal theme, but it is giving me the "$ is not function" error. I googled it, and changed the code bro the below, but it doesn't work either.  (function($) {   $('.slider').mobilyslider({     content: '.sliderContent',     children: 'div',     transition: 'horizontal',     animationSpeed: 500,     autoplay: true,     autoplaySpeed: 9000,     pauseOnHover: true,     bullets: true,     arrows: true,     arrowsHide: true,     prev: 'prev',     next: 'next',     animationStart: function(){},     animationComplete: function(){}   });    })(jQuery);   The above code gives me following error:     $('.slider').mobilyslider is not a function Replacing fonts in EPS/PDF files How do I create a script file for terminal commands? In Windows I can write a file containing commands for cmd (usually .cmd or .bat files).  When I click on those files it will open cmd.exe and run them commands the file contains.  How would I do this in Ubuntu?         I'm sure this is a duplicate, but I can't find my answer. Its similar to these questions, but they don't answer the question: Why are the even and odd Regge trajectories degenerate? Say there are $m+n$ elements split into two groups ($m$ and $n$). The variance of the first group is $\sigma_m^2$ and the variance of the second group is $\sigma^2_n$. The elements themselves are assumed to be unknown but I know the means $\mu_m$ and $\mu_n$.  Is there a way to calculate the combined variance $\sigma^2_{(m+n)}$?   The variance doesn't have to be unbiased so denominator is $(m+n)$ and not $(m+n-1)$. Intermediate fields between $\mathbb{Z}_2 (\sqrt{x},\sqrt{y})$ and $\mathbb{Z}_2 (x,y)$ Mirror changes to side of cube across all six sides What if an abbreviation is at the end of a declarative sentence? Should I duplicate a full stop sign? What if an abbreviation is at the end of a declarative sentence? Should I duplicate a full stop sign? If the following sentence begins with a proper noun, not putting two periods may be confusing, in theory. Edit: It used to be 'contraction' instead of 'abbreviation'.