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What are important/notable publishing houses for books in statistics?
When I come across a book published at O'Reilly or Springer I imagine its quality will be high. What other notable publishing houses are out there (for statistics books)? Any recommendation on a way to find out? (I'd imagine we could check it if we... |
I hope this is a stats question :) There's a game (RftG) with cards, each of which has various attributes (generally bonuses of some kind) and a price. I'm wondering if there's some kind of technique for determining the average value of each attribute, and therefore calculating the expected cost of each card as a whole... |
I'm not a statician/mathematician, so please be gentle with me
This is a cross-post from Stack Overflow. I'm working with a site that lets the users create 'sections'. Each section have multiple items which are voted. The best ones are shown in the main page.
I found that a simplistic approach to rank would be bad idea... |
I received this elementary question by email:
In a regression equation am I correct
in thinking that if the beta value is
positive the dependent variable has
increased in response to greater use
of the independent variable, and if
negative the dependent variable has
decreased in response to an increase
i... |
I'm wondering how to proceed to perform Canonical Correspondence Analysis and Multiple Correspondence Analysis in R on the following three-way contingency table
Eco_region3 Eco_region4 Species Freq
A A1 S1 10
A A1 S2 12
A A1 S3 8
... |
Say I want to classify my data into two categories. I am pretty sure that my data has been generated by two mixtures of Gaussians -- on has a bimodal and one a trimodal form.
I then train the generating models $p(x|c_1)$ and $p(x|c_2)$ and combine them via Bayes' theorem into a classifier of the form $p(c_i|x)$.
Since ... |
What is the difference between endogeneity and unobserved heterogeneity? I know that endogeneity comes for example from omitted variables? But as far as I understand, unobserved heterogeneity causes the same problem. But where exactly lays the difference between these two notions?
|
I'm trying to run R's multidimensional scaling algorithm, cmdscale, on roughly 2,200 variables, i.e. a 2,200x2,200 distance matrix. It's taking forever (about a day so far). I don't know much about the algorithm used under the hood. What's its big-O notation? Is a more efficient, even if only approximate, algorithm... |
I'm developing an application in which users can create 'sections' (à la subreddit in reddit), in which items/posts can be created and voted with a thumbs-up/down system.
A great article guided me on how to sort these votes so that an item with a 100% positive response but with few votes won't get ranked over one with ... |
I would like to compute the probability distribution for the length of the fragments which I would obtain by fragmenting a linear rod of length $L$ in the following way:
I choose at random (uniformly) $n$ breakpoints
I cut the rod at those breakpoints, creating $(n+1)$ fragments.
Now, while it is easy to see that th... |
I have to generate random numbers for my algorithm based on probability distributions. I want a distribution which has heavy tails and is unskewed, which can produce numbers far away from location parameter. There should be a parameter to control the tail heaviness (e.g., like levy distribution where alpha determines t... |
What are the pros and cons of learning about a distribution's properties algorithmically (via computer simulations) versus mathematically?
It seems like computer simulations can be an alternative learning method, especially for those new students who do not feel strong in calculus.
Also it seems that coding simulations... |
I have searched for this online for hours but none of online posts is what I am looking for. My question is very easy to implement in SAS Proc mixed procedure but I am not sure how to do it in lme and/or lmer packages. Assume, I have a model,
$y = \mu + \alpha + \beta +\alpha\beta + e$,
where $\alpha$ is fixed but $\b... |
I have data with standard error, included below for clarity,
X Y Error in Y
0.0105574 -28.831027 0.04422
0.0070382 -27.800385 0.04225
0.0052787 -27.314088 0.04209
0.0042229 -27.054207 0.04185
0.0035191 -27.000188 0.04143
0.0030164 -26.891275 0.04108
I h... |
I have a 37-question scale, where each item belongs to one of four scales.
The items for each scale are interspersed.
How can I compute a scale score for each of the four scales?
I need to be able to analyse each subscale independently and then compare scale responses on and independent variable.
|
I'm trying to do a mixture discriminant analysis for a mid-sized data.frame, and bumped into a problem: all my predictions are NA.
After tracing through way too much code, I figured it had something to do with the fact that some of the coefficients in the mda turn out to be NA. I've created a smaller data.frame that st... |
I am looking for a statistical method to define the variance/ diversity / inequality in a set of observations.
For example:
If I have following (n=4) observations using 4 data points, here the diversity/variance/inequality is zero.
A-B-C-D
A-B-C-D
A-B-C-D
A-B-C-D
In the following (n=4) observations using 7 data p... |
As question, I have found something similar here, but how to do it in R?
|
If i test two hypotheses, one of which has a null that is -in fact- false and the other has a null that is -in fact- true, I want to know the probability that the first test will obtain a p value less than that of the second, given other parameters such as delta, sigma, and sample size. I am not interested in whether o... |
I have a mixed effect model (in fact a generalized additive mixed model) that gives me predictions for a timeseries. To counter the autocorrelation, I use a corCAR1 model, given the fact I have missing data. The data is supposed to give me a total load, so I need to sum over the whole prediction interval. But I should ... |
If an exploratory factor analysis is done with some 1-5 agreement items and some 0/1 "choose all that apply" items, theoretically how much of a spurious tendency would there be for the 1-5 items to load on one or two factors and the 0/1 items to load on a separate set of one or two factors? (I've heard arguments both ... |
I am trying to figure out how R computes lag-k autocorrelation (apparently, it is the same formula used by Minitab and SAS), so that I can compare it to using Excel's CORREL function applied to the series and its k-lagged version. R and Excel (using CORREL) give slightly different autocorrelation values.
I'd also be in... |
I want to estimate the impact of having health insurance on health care expenditures and have a hunch that it is best to use a two-part model to first estimate the probability of using any health care and then estimating the amount spent by those who used health care. However, I am not clear on the advantage of using a... |
I have a question concerning random variables. Let us assume that we have two random variables $X$ and $Y$. Let's say $X$ is Poisson distributed with parameter $\lambda_1$, and $Y$ is Poisson distributed with parameter $\lambda_2$.
When you build the fracture from $X/Y$ and call this a random variable $Z$, how is this... |
I have a data set consisting of interactions between male-female dyads within a group in two conditions. The values range from -1 to 1 and indicate how responsible the female was for maintaining the relationship (Hinde's index). What I want to see is if the female responsibility changes in the two conditions. My unders... |
I am trying to increase my model accuracy by taking into account interaction effect of relevant variables.
I am choosing variables to interact based more on the common sense than on trying every combination.
So far most interaction effects with good p value ( p<.0001) and chi-square have resulted in an increase of tr... |
I am trying to model steel prices using brent prices with following model:
$steel_t=\alpha + \beta steel_{t-1}+\gamma brent_t + \epsilon_t$
I have monthly data. I fitted the parameter values with lm (R, is that reasonable?). Now I want to see the effect of a "shock event" in one year, e.g. what happens to steel prices... |
I have data like Person $A$ like movies ['X','Y', 'Z'] and he dislikes ['V']. Person $B$ like movies ['X','L','V'] and dislikes ['Y']. like wise so many users. What could be a good algorithm to find mean difference of users' tastes?
|
I was presenting proofs of WLLN and a version of SLLN (assuming bounded 4th central moment) when somebody asked which measure is the probability with respect too and I realised that, on reflection, I wasn't quite sure.
It seems that it is straightforward, since in both laws we have a sequence of $X_{i}$'s, independent ... |
I'm using the ets forecast function in R.
When I fit a model to some timeseries t1:
model<-ets(t1) [36 periods]
and the calculate forecasts from that model:
f1 <- forecast(model,10)
so i get 10 forecasts for periods 37-48
so my question is, are these 10 point-forecast one-step-ahead forecasts wich
have their s... |
For an upcoming study of about 200 (rare) cancer cases, we would like to determine the power of detection for a hypothetical marker, present in 10% of cases, i.e. 20 cases with a hazard ratio of 3.0. Cases will be followed up for at least 5 years. We will have the option to validate any identified markers in an indepen... |
Is there a (stronger?) alternative to the arcsin square root transformation for percentage/proportion data? In the data set I'm working on at the moment, marked
heteroscedasticity remains after I apply this transformation, i.e. the plot of residuals vs. fitted values is still very much rhomboid.
Edited to respond to... |
I am looking for an easy to use stand alone software that is able to construct Bayesian belief networks out of data. The software should (of course ;-) be free.
Can anybody recommend something? Thank you!
|
I'm re-posting a question from math.stackexchange.com, I think the current answer in math.se is not right.
Select $n$ numbers from a set $\{1,2,...,U\}$, $y_i$ is the $i$th number selected, and $x_i$ is the rank of $y_i$ in the $n$ numbers. The selection is without replacement. $n$ is always smaller than $U$. The rank ... |
I am a newbie in stat. I am working on the Laplace distribution for my algorithm.
Could tell me the first what the four moments of the Laplace distribution are?
Does it have infinite tail like the Cauchy distribution?
What is the empirical rule?
|
I'm having a hard time explaining this (hence the weird and long title), also I'm not a mathematician, I have this data lying around in a database and was wondering how I could visualise it (and predict the future)
Say I gave you the following data for one user, it can show anything, for example say it shows whether so... |
Can anybody show me, why the dispersion parameter of the negative binomial distribution is taken to be one? In the Poisson case you can show that $E(y)/V(y)=\mu/\mu=1$ which is called equidispersion. But how can you show that the dispersion parameter of the negative binomial distribution is 1 as well?
|
I am trying to find some help with something that is called an "Adjusted Analysis" (or also Covariate Adjusted Logistic Regression); a typical response has been that I might just want multivariable logistic regression, but this is not quite what I am looking for. The trouble I have is with what exactly an "adjusted" a... |
I am looking for input on how others organize their R code and output.
My current practice is to write code in blocks in a text file as such:
#=================================================
# 19 May 2011
date()
# Correlation analysis of variables in sed summary
load("/media/working/working_files/R_working/sed_OM_s... |
I want to test a multi-stage path model (e.g., A predicts B, B predicts C, C predicts D) where all of my variables are individual observations nested within groups. So far I've been doing this through multiple unique multilevel analysis in R.
I would prefer to use a technique like SEM that lets me test multiple paths a... |
I'd like to regress a vector B against each of the columns in a matrix A. This is trivial if there are no missing data, but if matrix A contains missing values, then my regression against A is constrained to include only rows where all values are present (the default na.omit behavior). This produces incorrect results f... |
I have a mixed ANOVA with one between and one within factor:
between factor: control versus treament
within factor: ad1, ad2 (measures click rates on 2 ads)
aov(repdat~(within*between)+Error(subjcts/(withincontrasts))+(between),data.rep)
However my outcome repdat has a Poisson distribution and 0s (since sometimes use... |
I was wondering how to get arguments for R functions. Is there any R function which can be used to get all arguments for a certain function?
As R function glm has the following arguments
glm(formula, family = gaussian, data, weights, subset,
na.action, start = NULL, etastart, mustart, offset,
control = list(...), model... |
I am performing this simple experiment: I have one variety of grass and 8 different fungi (say #1 to #8). I am going to put 10-20 grass plants in each one of 18 containers, and then I will put each one of the fungi in 2 containers and let 2 with no fungus ("negative control").
After some time I will count how many plan... |
I made a comparison of hatch success between 2 populations of birds using R's prop.test() function:
prop.test(c(#hatched_site1, #hatched_site2),c(#laid_site1, #laid_site2))
It gave me the proportions of each site as part of the summary. How can I calculate the standard error for each proportion?
|
Is it ever valid to include a two-way interaction in a model without including the main effects? What if your hypothesis is only about the interaction, do you still need to include the main effects?
|
I understand that SPSS can create a contingency table, and at the same time perform the chi-square test.
However, is it possible that when we already have the contingency table, to have SPSS do the chi-square test?
|
The latest general framework I know in MCMC-based wrapper method (doing variable selection and clustering simultaneously) are the paper "Bayesian variable selection in clustering high-dimensional data" of Tadesse et al (2005) and the paper "Variable selection in clustering via Dirichlet process mixture models" of Kim e... |
Let's aim for some at an introductory level, some articles and some textbooks. Applied is more helpful, including R code is great. Thanks!
|
I am doing text classification, and have been playing around with different classifiers. However I have a pretty basic question: what if a new unseen document comes in and it happens to not belong to any of the pre-existing classes? The classifiers that I have seen (in WEKA, libsvm etc.) still go ahead and put the unse... |
It has come to my attention that companies will rank resumes based on buzz words and only look at those that have high scores assuming enough people submit for the position.
I don't like this system but still want a job, so instead of inserting these meaningless terms into my actual resume I've compiled a list of such ... |
My problem is to figure out an algorithm for summarising wind statistics over an area. The statistics are (24x) hourly but I want to end up with 2-3 'blocks' that summarise the conditions for the whole day.
My data is in the form of separate magnitude and direction NumPy arrays but I could convert them to u,v or polar ... |
What are the benefits of giving certain initial values to transition probabilities in a Hidden Markov Model? Eventually system will learn them, so what is the point of giving values other than random ones? Does underlying algorithm make a difference such as Baum–Welch?
If I know the transition probabilities at the beg... |
I have a model fitted (from the literature). I also have the raw data for the predictive variables.
What's the equation I should be using to get probabilities? Basically, how do I combine raw data and coefficients to get probabilities?
|
I want to run a multiple regression analysis measuring the effect of various independent variables on a continuous dependent variable measuring the strength of a political institution. The problem is that the data is measured in different years. Thus I might have data for countries A and B only for the year 2009 and fo... |
I am trying to study the public opinion concept linked to quantitative measurement of opinion distributions and i am trying to define major parameters and methods that can help me starting from a certain finite number of people replying to a survey to generalize the results of that survey to say that this result can be... |
I want to determine the amount of food stamp fraud a retailer perpetrated based on food stamp sales in other stores. The retailer had both legitimate food stamps sales, and illegitimate sales. The illegitimate sales consisted of food stamps used to buy ineligible items or whee food stamps were illegally redeemed for ca... |
I have a dataset of 380 samples of 6 variables. These variables are counts of different types of events in each of the 380 defined regions. These counts are per month, which means that I have several of these datasets (for now, I only have four months).
When looking at the data, I can clearly see that there is some mis... |
I find that simple data analysis exercises can often help to illustrate and clarify statistical concepts. What data analysis exercises do you use to teach statistical concepts?
|
For my classification problem, I am trying to classify an object as Good or Bad. I have been able to create a good first classification step that separates the data into 2 groups using SVM.
After tuning the parameters for the SVM using a training/holdout set (75% training, 25% holdout), I obtained the following result... |
I'm hoping someone can help me sort out how the proportion comparisons using a GLM works in R.
I'm comparing hatch success among multiple years (and later, sites). I've used a GLM to compare among years by making a txt file where the success column contains the number of chicks that hatched, and failures are the number... |
In a number of statistical packages including SAS, SPSS and maybe more, there is an option to "suppress the intercept". Why would you want to do that?
|
I'm estimating a GLM with a bunch of parameters in R.
When I run this:
M <- glm( Y ~ factor(X1) + factor(X2) )
summary(M)
R only gives me part of the table, then cuts out with the message:
[ reached getOption("max.print") -- omitted 621 rows ]]
The summary table will be big, but I want the whole thing. How do... |
The "Linear Ballistic Accumulator" model (LBA) is a rather successful model for human behaviour in speeded simple decision tasks. Donkin et al (2009, PDF) provide code that permits estimating the parameters of the model given human behavioural data, and I've copied this code (with some minor formatting changes) to a gi... |
This is perhaps basic but I couldn't find a suitable reference.
I have a regression model with a rather complicated link function.
So $\vec{x}$ is a vector of continuous predictors, and $z$ is a binary variable such
that according to the model: $Pr(z=1) = f(\vec{x})$ for some (known) function $f$.
I observe data o... |
I need help because I don´t know if the command for the ANOVA analysis I am
performing in R is correct. Indeed using the function aov I get the following error: In aov (......) Error() model is singular
The structure of my table is the following: subject, stimulus, condition, sex, response
Example:
subject stimulus co... |
I've received a results from a Mann-Whitney rank test that I don't understand.
The median of the 2 populations is identical (6.9). The uppper and lower quantiles of each population are:
6.64 & 7.2
6.60 & 7.1
The p-value resulting from the test comparing these populations is 0.007. How can these populations be signif... |
I have conducted a search for genetic interactions using a simple dosage model:
Y ~ A + B + AB
where Y is the phenotype, in this case, gene expression values and A and B are vectors of genotype information for ~500 samples. I wish to determine a signficance threshold using permutation testing in order to correct for mu... |
I was just wondering why regression problems are called "regression" problems. What is the story behind the name?
One definition for regression:
"Relapse to a less perfect or
developed state."
|
I am a newbie in stat. I am completing my thesis in Evolutionary algorithm. I have to generate some random numbers from T-distribution or Laplace distribution. How can I do this?
An easy and simple explanation would be appreciated.
|
I believe that independent variables $X_1,X_2$ affect the dependent variable $Y$ through a latent variable $Z$ such that
$$
\begin{align}
Y &= \beta_0 + \beta_1Z \\
Z &= \operatorname{Logit}^{-1}(\beta_2X_1 + \beta_3X_2) \\
\\
Y &= \beta_0 + \beta_1\operatorname{Logit}^{-1}(\beta_2X_1 + \beta_3X_2)
\end{align}
... |
Apologies for what is probably a very basic question. I have looked around both here and in the usual places and haven't had any luck.
I have read that there are at least two methods for linearly transforming data so that you can give your distribution a certain desired standard deviation. What are they and are there c... |
How can I interpret the main effects (coefficients for dummy-coded factor) in a Poisson regression?
Assume the following example:
treatment <- factor(rep(c(1, 2), c(43, 41)),
levels = c(1, 2),
labels = c("placebo", "treated"))
improved <- factor(rep(c(1, 2, 3, 1... |
I was trying to do a test of reliability for my survey items. In addition to Cronbach's alpha I'm looking at communalities. My criteria is that survey items with communality below 0.4 will be dropped. But when I looked at my communality table, I saw that some items had .99 for communality. Is this problematic? What sho... |
I'm having trouble performing factor analysis on my dataset.
When I perform the factor analysis in SPSS (default settings), it works fine. Problem is, I need to do it programmatically (in Python). When I try using Python (MDP library) to do factor analysis on the same dataset, I get this error:
"The covariance matrix... |
I am a newbie in stat. I am completing my thesis in Evolutionary algorithm. I have to generate some random numbers from Laplace distribution. How can I do this using matlab?
An easy and simple explanation would be appreciated. Thanks in advance.
|
I need to do a logistic regression using R on my data. My response variable (y) is survival at weaning (surv=0; did not surv=1) and I have several independent variables which are binary and categoricals in nature.
I am following some examples on this website http://www.ats.ucla.edu/stat/r/dae/logit.htm and trying to ru... |
Take a look at this photo:
It depicts a box plot of series of identical runs for successive i values. (AFAIK it's the standard Min/Max and 1rst, 2nd, 3rd quartiles.) So the x-axis of 1 represents 1000 runs where i=1; and the second plot shows 1000 runs where i=2; and so on.
It's easy to eye-ball and see that there's... |
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 y... |
I have some data acquired by an acoustic sensor with 1 Hz sampling rate. Due to some inevitable issues, I have some noise in my signal, saying 10% pollution.
I'm looking for a reliable method for replacing the outliers.
In order to find a suitable approach I manipulated a clean record such that it contains 9% spurious ... |
I am using ANOVA with repeated measures to test significance between males and females results of an experiment during which participants had to evaluate 7 stimuli in 2 conditions (EXP1 and EXP2).
The problem is that even if from results it is clear that there are significant differences between males and females, I do... |
Does anybody know how to plot all AIC values for different size models, when using the command regsubsets from the package leaps?
Assume you have the following variables:
treatment <- factor(rep(c(1, 2), c(43, 41)), levels = c(1, 2),labels = c("placebo", "treated"))
improved <- factor(rep(c(1, 2, 3, 1, 2, 3), c(29, 7,... |
Given a data frame in R is there a way to export it in R syntax such that executing this code would re-create the data frame? I would find this useful to store results in R files along with calculations without depending on external files.
|
I have 5 emerging market foreign exchange total return series, for which I am forecasting single period future returns (1 year). I would like to construct a Markowitz mean variance optimized portfolio of the 5 series, using historical variances and covariances (1) and my own forecast expected returns. Does R have an (e... |
I've been using R to run GLMs with the logit link to compare clutch sizes (a binomial data set) and proportional data among several years. I now need to compare 2 groups of years (good years and poor years) between 2 sites for the same data.
I am not interested in any interactions between year-type (good or poor) and s... |
I have 2 dependent variables (DVs) each of whose score may be influenced by the set of 7 independent variables (IVs). DVs are continuous, while the set of IVs consists of a mix of continuous and binary coded variables. (In code below continuous variables are written in upper case letters and binary variables in lower c... |
I am wondering if there is a sample size formula like Lehr's formula that applies to an F-test? Lehr's formula for t-tests is $n = 16 / \Delta^2$, where $\Delta$ is the effect size (e.g. $\Delta = (\mu_1 - \mu_2) / \sigma$). This can be generalized to $n = c / \Delta^2$ where $c$ is a constant that depends on the type ... |
I was playing around with writing a code for Montecarlo integration of a function defined in spherical coordinates. As a first simple rapid test I decided to write a test code to obtain the solid angle under an angle $\theta_m$. For two random number $u$ and $v$ in $[0,1)$. I generate a homogeneous random sampling of ... |
I am doing a meta analysis for the first time and have a few basic questions regarding statistical analysis.
Let's say I have one study where the primary outcome (thrombosis) in the 2 treatment groups (intervention v. placebo) was compared using the Mantel-Haenszel chi-square test. It does not report df in the articl... |
Context
I have a multivariate dataset with a test group and three control groups.
I was thinking that the best way to determine if and how the test group differed from all of the control groups would be to perform a MANOVA, then perform contrast analysis between the test group and all of the control groups.
Main Questi... |
Given an hierarchical clustering of data points, some of which are labeled, are there good ways to use the tree/dendrogram to make predictions for the unlabeled points?
One approach might be to find the "best" place to cut the tree so that clusters match labels.
I'd be especially interested in efficient ways to cut eac... |
I know I'm asking a lot of questions these days! Sorry about that, but I'm trying to work through my grad thesis data collected over the last 4 years, and am repeatedly tripping on my beginner's grasp on stats.
The background:
My basic question is the same as described in another question on this site. In brief, I'm tr... |
I participate in predictive modeling competitions on Kaggle, TunedIt, and CrowdAnalytix. I find that these sites are a good way to "work-out" for statistics/machine learning.
Are there any other sites I should know about?
How do you all feel about competitions where the host intends to profit from competitors' submi... |
Suppose I thought that ingesting greater than 100 mg of chemical X annually noticeably decreased one's weight. Also, I had data (from a "natural" experiment) from 100 people (some male and some female) measuring how much of chemical X they had eaten, and their weights at the time of the experiment.
What is the best w... |
Is the method of mean substitution for replacing missing data out of date? Are there more sophisticated models that should be used? If so, what are they?
|
I am going to be hosting a number (~10) of potluck meals over the course of the summer, my pool of people to invite is about 40 people with about 10-15 coming to each meal. So I figure this would be a good opportunity to record data over time about the meals/people. The issue I am having is I am not sure what informati... |
I have time series data that represent dates/times of trades taken in a financial market.
I would like to assign a score to this data that represents whether the trades are mostly clustered around particular time values or if they are mostly spread out evenly. I am going to have about 1000+ results per dataset.
Examp... |
I have a sequence of integers that represent total sales of my product for each day. From time to time, we have large press or marketing events that increase sales on the day of the event and for a few days after that but then eventually taper down to the long-run average. Here's some made-up numbers showing what I mea... |
I would like to test that two difference/distance/dissimilarity matrices are not the same. i.e. the rows and columns between the two matrices represent the same features, but the distances are obtained from 2 populations and I'm interested in whether the difference matrices "look different" between the populations.
I'm... |
Suppose we have 500 students nested in 20 classes (different classrooms), 25 students per class
student<-factor(1:500)
class<-rep(LETTERS[1:20],each=25)
They all take a test.
score<-rnorm(500,mean=80,sd=5)
The model below would tell you about the average scores and variability among students and classes
library(lme4)... |
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