instruction stringlengths 9 38.7k |
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This question is in some way similar to this one, but about another nuance.
I have two time series (update: stationary - with both mean and variance equal over time) with missing values in one of them, such as
1,2,3
1,Absent,3
(in reality I have many more observations). I want to compute their correlation, so I will ... |
What are some applications of Chinese restaurant processes?
I'm trying to learn a bit about non-parametric Bayesian methods, starting with Dirichlet processes and CRPs, but all the tutorials I've found are about theory, without describing any applications in depth.
Names of papers would be great. I'm not really looking... |
I typically deal with data where multiple individuals are each measured multiple times in each of 2 or more conditions. I have recently been playing with mixed effects modelling to evaluate evidence for differences between conditions, modelling individual as a random effect. To visualize uncertainty regarding the predi... |
I've been playing around with random forests for regression and am having difficulty working out exactly what the two measures of importance mean, and how they should be interpreted.
The importance() function gives two values for each variable: %IncMSE and IncNodePurity.
Is there simple interpretations for these 2 valu... |
As stated in the question, what sort of modeling technique would be most appropriate?
|
I have almost the same questions like this:
How can I efficiently model the sum of Bernoulli random variables?
But the setting is quite different:
$S=\sum_{i=1,N}{X_i}$, $P(X_{i}=1)=p_i$, $N$~20, $p_i$~0.1
We have the data for the outcomes of Bernoulli random variables: $X_{i,j}$ , $S_j=\sum_{i=1,N}{X_{i,j}}$
If we es... |
I have to plot a graph with log distribution on y axis. The values are: 10^-3..10^3.
What software do you suggest me to use.
My OS is Ubuntu, so I prefer software for Linux.
Thanks.
|
I am currently generating data by simulating a model of chemical system under different conditions (temperature) over time. In each simulation, the starting structure being modeled is exactly the same - only the temperature is different. The system is allowed to propagate over time and the length and number of observat... |
I used my training dataset to fit cluster using kmenas function
fit <- kmeans(ca.data, 2);
How can I use fit object to predict cluster membership in a new dataset?
Thanks
|
This may be a silly question, but I'm not seeing a clear answer in any of the usual sources. I'm preparing to build a Bayesian model to fit with BUGS/JAGS, currently working through the model logic in plate notation.
I have a few kinds of observed variables, and several latent variables. I know that a Bayesian model ... |
I have a problem that I don't think I've met before.
I have N observations of the variables v1 and v2 and I assume that there is a function f such as v2 = f(v1).
I want to know if f has a particular 'statistical' monotony (increasing or decreasing) and if it is 'statistically' convex or concave.
By 'statistical' I mean... |
I'm trying to estimate the unknown 8x8 covariance matrix X in R using the maximum likehood, but I have problems of figuring out the efficient way of parametrization of X when some of the covariances in X are constrained to zero. When there's no constraints, I have used a cholesky factorization, ie. I have parameters wh... |
I was wondering how the Bayesians in the CrossValidated community view the problem of model uncertainty and how they prefer to deal with it? I will try to pose my question in two parts:
How important (in your experience / opinion) is dealing with model uncertainty? I haven't found any papers dealing with this issue in... |
I am having trouble understanding the following. Let $\mu$ and $\sigma^2$ be the true mean and variance, $\bar{x}$ and $s^2$ the measured mean and variance for a random variable $x$, where $$\displaystyle s^2 = \frac{1}{N+k}\sum_i (x_i-\bar{x})^2.$$
If $s^2$ is an unbiased estimate
of variance then $k=-1$.
If $s^2... |
Here is an ANOVA model with one between-subject factor (condition; 4 levels) and one within-subject factor (trial_seq; 20 levels).
amod = aov(decision_quality ~ condition*trial_seq +
Error(user_id/trial_seq), data = d.task1)
summary(amod)
I want to do a pairwise analysis for both the between-subject factor and... |
The title says it all. Specifically: given strictly positive real numbers $a_1,\dots,a_T$ and $b_1,\dots,b_T$, I want to sample from $$\mu:=\text{Uniform}(\{p\in[0,\infty)^T : \sum_{t=1}^T a_t p_t = 1\}\cap\{p\in[0,\infty)^T : \sum_{i=1}^T b_t p_t = 1\}),$$ assuming that the intersection is nonempty.
My best attempt so... |
Here's the thread I got the idea from: http://www.quora.com/Do-men-have-a-wider-variance-of-intelligence-than-women/answer/Ed-Yong
Basically, this is a model that might be able to explain why there aren't more females in prestigious math/science competitions - it might be a statistical artifact arising from the simple ... |
I have carried out PCA and then clustered the 6 resultant components using K-means clustering technique using SPSS. Normally SPSS adds a class variable for each case indicating its assigned group.
Is there any other method I can "calculate" the class variable (i.e. using component scores and REGR factor scores for the... |
The Box-Jenkins model selection procedure in time series analysis begins by looking at the autocorrelation and partial autocorrelation functions of the series. These plots can suggest the appropriate $p$ and $q$ in an ARMA$(p,q)$ model. The procedure continues by asking the user to apply the AIC/BIC criteria to select ... |
This is a simple question. I am dealing with a "clipped" normal distribution -- say, $N(0,0.5)$ clipped between $[-1,1]$. I would like to calculate the "probability" of a sample, but I know that in $(-1,1)$, the probability of a single event is 0. However, the probability of 1 is $1-\text{cdf}(1,0,0.5)$ and -1 is $\... |
I'm writing a bit of code that makes pretty heavy use of sampling (eg, MCMC, Particle Filters, etc), and I would really like to test it to make sure that it's doing what I think it is before claiming any results. Is there a typical way unit test these methods to ensure correctness?
|
How do you do normalization so that when I get the mean/variance, the flat values wont affect the results? For example, in the figure below, Graph 1 & 2 are both considered to be noisy as compared to Graph 3.
However, as you can see, each of their flat intensity values vary from each other, so it could be possible th... |
I was recently asked:
Is there an R implementation of a significance test for testing whether three or more correlations drawn from independent samples are equal?
I found this formula which wouldn't be too difficult to implement, but I was curious whether there was an existing implementation either based on the linke... |
Does anybody know how to compare two positive predictive value (PPV) from two different predictive models? I found
some papers reporting $\chi^2$-test or Fisher exact test but I can´t figure out how the contingency tables would look like: They cannot be the same as for sensitivity/specifity tests, can they?
To clarify:... |
EDIT: The Web Technologies and Services CRAN task view contains a much more comprehensive list of data sources and APIs available in R. You can submit a pull request on github if you wish to add a package to the task view.
I'm making a list of the various data feeds that are already hooked into R or that are easy to ... |
This wiki page Simple linear regression has formulas to calculate $\alpha$ and $\beta$. Could anyone tell me how to derive the formulas in weighted case?
|
Context
Let $\mathbf{x}_i \in \mathbb{R}^{100}$ and $\mathbf{z}_i \in \mathbb{R}^{20}$ be input vectors with the same corresponding target $\mathbf{y}_i \in \mathbb{R}^{25}$.
Using ridge regression we obtain two separate mappings, $\mathbf{A}_\mathbf{x}$ and $\mathbf{A}_\mathbf{z}$, such that
$$\mathbf{A}_\mathbf{x}\ma... |
I'm reading in a paper "the goal is to cluster data in a way that is meaningful and at the same time as orthogonal as possible to the given classification"
Could someone have any idea how the notion of orthogonality is used in this case?
|
I would like to calculate the following conditional probability:
I know that the probability of a BLUE ball being drawn is 0.3.
I receive a message from A or B who saw the ball that has been drawn.
This person tells me that the ball drawn is BLUE.
I know the probabilities:
A observing BLUE and sending BLUE- 0.16
B obse... |
Our lab used to have a program called GS+ that let us make semi variograms on our data and analyse them. Unfortunately, the licence has expired.
Is there another piece of software that lets you do this? If so, how specifically? We prefer a free and open source licence, but all suggestions are welcome.
|
I have a population of 300 cases. It's split in three sub-populations 50, 50 and 200 in size.
I have developed three (different) models resulting in a score variable which rank orders each of the sub-populations separately. The score-ranges for all three segments are different ... 40 to 240, 20-410 and 4 to 600. With... |
I am looking for papers or texts that compare and discuss (either empirically or theoretically):
Boosting and Decision trees algorithms such as Random Forests or AdaBoost, and GentleBoost applied to decision trees.
with
Deep learning methods such as Restricted Boltzmann Machines, Hierarchical Temporal Memory, Convo... |
I want to calculate Kullback–Leibler divergence on two documents. It requires probability distribution of each document.
I do not know how to calculate probability for each document. Any simple answer with layman example would be much appreciated.
Let's say we have follow two documents:
1 - cross validated answers are... |
Consider a scenario where you are provided with KnownLabel Matrix and PredictedLabel matrix. I would like to measure the goodness of the PredictedLabel matrix against the KnownLabel Matrix.
But the challenge here is that KnownLabel Matrix have few rows only one 1 and other few rows have many 1's (those instance are mul... |
I am performing some analysis on understanding various characteristics of a certain population. To narrow down my selection (as I will be going through them manually), I am using different thresholds on certain measurable properties (which tell me how relevant someone is) to draw the following frequency graph. For inst... |
I have made several experiments, the result graphs are below, I need to figure out what is the distribution function of the following random variables... Where do I start with statistical analysis of my experiment?
How to perform these analysis with spss?
EDIT
Explanations: I'm testing algorithm efficiency for 2 algo... |
I have 5 single factor regression models. Each has intuitive (positive) coefficients which is good. If I run multiple logistic regression one of the coefficients turns negative.
If I run stepwise selection, the negative coefficient stays in ... it's not redundant ...
How should I deal with this? Is there a way to enfor... |
I have a large dataset and have performed a multilevel regression in Stata, the model is the following:
xtmixed dependent independen1 independent2 independent3 independent4 || independendt5:
So there is one grouping factor: independent5
In R I did the following:
lmer(dependent ~ independent1 + indepdendent2 + indep... |
I have case fatality rates (deaths per 100 cases) for 2 different states receiving different treatments for 17 years.
What is the best statistical method to compare them? Relative risk, odds ratio, plain time series analysis, ...?
The data is like this:
Year St.1 Cases St.1 Deaths St.1 CFR St.2 Cases St.2 Deaths St... |
I want to apply a GAMM with R to this time series but I am not sure how to handle the station P18, as shown in the figure below.
If I shrink the dataset to the point where P18 ends (i.e. left side of the dashed line) I would loose many reversing trends in P07,P14,P22,P2O and so on.
The question is thus: can I use the... |
I am using a mixed repeated measures with an ARMA(1,1) variance covariance structure. I have a basic understanding of why I am using this model etc but I need some help on articulating a few things:
How does this model correct for the variance in time between each time point? Or does it ignore the problem? In which ca... |
I am always struggling with normality testing for quantitative predictors (no factors) and transforming them to normality.
If I am running a GLMM and my predictors are really non-normal, should I transform them as well to try to make them normally distributed?
I know that this is important for the response variable... |
I have three product categories, $A,B,C$. Each category has two products, $0,1$. I provide a number of different kinds of choice situations, 1) the test subject is presented a single category and made to choose a product, 2) the test subject is presented with two categories and made to choose a product from two categor... |
I'm trying to train a single layer of an autoencoder using minFunc, and while the cost function appears to decrease, when enabled, the DerivativeCheck fails. The code I'm using is as close to textbook values as possible, though extremely simplified.
The loss function I'm using is the squared-error:
$ J(W; x) = \frac{1... |
I have a dataset that includes an open-ended response that was coded into categories by a vendor. The vendor created 50 multi-punch categories stored as 50 true/false variables.
By putting this in a multiple response set and cross-tabbing it with itself I can see that most responses seem to be in a small number of cat... |
I would like to plot 2D confidence regions (at 1-sigma, 2-sigma) for a model that I've fit to data. I've used PyMC to generate 50k MCMC posterior samples for my model with 6 parameters.
I know the process to create confidence regions is something similar to:
1.) create a histogram of the samples in the 2D space
2.) id... |
I posted this on maths, but seems it would be better here :S
https://math.stackexchange.com/questions/49941/calculate-the-rate-of-change
Basically
I am trying to calculate the change frequency for a set of data. Each bit of data has the date-time it was created. I would like to say for a specific set of data the chang... |
I'm just facing an issue of finding an easy tutorial or guide to the funnel plot.
Are there simple resources you recommend for this?
Thanks.
|
A/B testing:
http://20bits.com/articles/statistical-analysis-and-ab-testing/
http://elem.com/~btilly/effective-ab-testing/
I'm not too familiar with A/B testing, but I was wondering if there were any specific packages/libraries in R or Python that can be used to perform A/B testing.
|
I'd like to calculate the conditional probability in the following case:
I was told that a box contains a BLUE ball. this is my evidence, my prior probability of a BLUE being drawn is 0.3. and this message can come from a friend(0.6) or an enemy (0.4)
I also know the probabilities of:
a friend observing BLUE : 0.16
a f... |
So, I'm working on a problem where I have a sample distribution with a reported, mean and an asymmetric confidence interval from bootstrapped sampling of the initial population (this is from a meta-analysis - so, I also have the # of bootstrap replicates and the original sample size). Given this information, I would l... |
I would like to know how to estimate a population average model of a hierarchical logistic regression using R package geepack.
The Stata code is:
xtlogit dep ind1 ind2 ind3, i(ind4) pa
I would like to reproduce this in R using geepack or any other method.
|
I am looking to study a particular type of error on a cognitive test to evaluate for potential clinical implications. As there is no existing research on this variable, I would like to run a pilot evaluation on a relatively large pool of subject data from our clinic (feasibly this would be about 200 subjects) to see i... |
So... let's say I have data that look something like this...
(as I look at it now, in the actual data the red line is about 20% shorter than the black (at the high end... but you get the idea)
I've made a mixed effects model (lmer) where there's an effect of the x-predictor and and also an effect of the two colours. ... |
I am looking for a variable selection technique in R to reduce the number of my regression predictors, where I can force the method to keep a specific variable within the model. Here is a toy example from the R help of ?step, the variable "Examination" will be removed:
summary(lm1 <- lm(Fertility ~ ., data = swiss));
s... |
There's not much more I can add to the question. Googling has mostly turned up research papers on springerlink and other sites I don't have access to.
Given a neural network model with $tanh(x)$ as the output non-linearity, what is the appropriate matching loss function to use?
-Brian
|
Last night I started a complex calculation with gamm() and it took me...
user system elapsed
9259.76 326.05 9622.64 (s)
...meaning it took me 160 minutes or 2.67 hours for that calculation. The problem is that I have to do around 50 or even 100 more of these! So I was wondering if the... |
I am currently trying to estimate the density of a joint distribution of K single dimensional RVs. I have at my disposal a set of N sample points, each of which represents an outcome of the K RVs.
Some specifics about my problem:
the RVs are independent
the RVs need not belong to same family of distributions
the RVs ... |
What is a good measure of spread for a multivariate normal distribution?
I was thinking about using an average of the component standard deviations; perhaps the trace of the covariance matrix divided by the number of dimensions, or a version of that. Is that any good?
Thanks
|
I need to fit a generalized Gaussian distribution to a 7-dim cloud of points containing quite a significant number of outliers with high leverage. Do you know any good R package for this job?
|
I have been asked to analyse some data from a clinical trial looking a two methods of measuring blood pressure. I have data from 50 subjects, each with between 2 and 57 measures using each method.
I'm wondering how best to proceed.
Obviously I need a solution that will account for the fact the measure of blood pres... |
I would like to fit a 3-level hierarchical regression in lmer, however, I don't know how to specify the grouping factor above the second level.
the model would be:
lmer(depedent ~ independent 1 + independent2 + (1|group1)....
And I would like to specify another group nested within group1.
I've tried (1|group1/group2) ... |
I run several simulation studies with R using a MacBook Pro, which has 8 GB of RAM. Unfortunately, some of the simulations cannot be done due to limited memory. My question is how much RAM is needed for large simulations? (For example, each data set has 10000 subjects and needs to generate 1000 datasets). Is 64 GB of R... |
I want to build a model to predict the outcomes of experiments.
My predictive model gives out scores with an range 1 to 100 values.
I want to test if my predictive scores can be used to classify experimental outcomes as "good" or "bad" groups.
Experimentally, we did the 1000 experiments. Using my predictive model, I h... |
INTRODUCTION: I'm a bioinformatician. In my analysis which I perform on all human genes (about 20 000) I search for a particular short sequence motif to check how many times this motif occurs in each gene.
Genes are 'written' in a linear sequence in four letters (A,T,G,C). For example: CGTAGGGGGTTTAC... This is the fou... |
I have 5 more less correlated variables measuring conceptually same thing - size. For example, height, weight, shoe size, jacket size and age. I just want to summarize the information from all variables into one and use that single (synthetic) variable in further analysis.
What are the options for doing that?
One of th... |
I am having trouble figuring out how to group data using the inter-quartile ranges calculated with a box and whiskers plot as well as looking at Tukey's Hinges. I understand the IQR and Tukey's hinges are not the same thing and that there are different interpretations of Tukey's Hinges. Basically, I did a calculation u... |
In Ackley and Hinton's paper "A Learning Algorithm for Boltzmann Machines", they write that
A hidden unit would be needed, for
example, if the environment demanded
that the states of three visible units
should have even parity-a regularity
that cannot be enforced by pairwise
interactions alone.
Could someo... |
This is more a general question on machine learning in general, but I have two datasets ~75k rows of patients and 100 columns (call it training and testing)--each column is either a numeric predictor corresponding to how many times they've visited a specific physician, or a factor (two examples are Gender and 10-year a... |
Quite simple, I have some probability distribution p(x), how can I measure whether one empirical density (set of delta masses) is a better approximation than another. I know that KL-divergence is a well accepted measure between two continuous densities, but it's not clear how to apply that to a set of samples.
|
I thought that the loadings in factor analysis were the correlations between the observed variables and the latent factors. However, when I do factor analysis in R using the psych package, this does not seem to be the case:
library(psych)
set.seed(1)
X <- matrix(rnorm(200), ncol=10)
fa1 <- fa(X, nfactor... |
Context
I have 25 men and 25 women as participants, and they did exactly the same thing: Each of them
heard an attractive dialogue and they had to choose between a photo of a
woman in red and a woman in green. Then each of them heard an unattractive
dialogue and they chose again between the red and the green shirt.
My... |
(Step 1) Using my predictive model, I predicted 1000 scores for my sample dataset.
(Step 2) I then calculate the random score using the same method for a randomized dataset. I firstly fit the distribution of the random score.
(Step 3) For each of my predictive score (1000 scores, in step 1), I calculated the p-valu... |
I have a regression done on two groups of the sample based on a moderating variable (say gender). I'm doing a simple test for the moderating effect by checking whether the significance of the regression is lost on one set while remains in the other.
Q1: The above method is valid, isn't it?
Q2: The level of confidence o... |
I'm quite enamoured with likelihood ratios as a means of quantifying relative evidence in scientific endeavours. However, in practice I find that the raw likelihood ratio can get unprintably large, so I've taken to log-transforming them, which has the nice side-benefit of representing evidence for/against the denominat... |
I would like to know if it is useful (or maybe dangerous) to reduce the number of attributes (by selecting the most informative ones among thousands) before seeking for latent variables or not (in an exploratory perspective).
A subsidiary question: in the same case, would it be beneficial to select the most important f... |
It seems universal that demographic statistics are given in terms of 100,000 population per year. For instance, suicide rates, homicide rates, disability-adjusted life year, the list goes on. Why?
If we were talking about chemistry, parts per million (ppm) is common. Why is the act of counting people looked at funda... |
This is a very basic question, so please bear with me.
I've been learning about AB Testing, which is largely used in internet marketing to examine the effectiveness of certain aspects of ads, websites, etc.
Here's a couple links to people who want to know more about AB Testing:
http://visualwebsiteoptimizer.com/split-t... |
I'm trying to run a 3 level hierarchical regression in lmer in R.
The model is specified:
model <- lmer(dependent ~ ind1 + ... + (1|level3/level2), data=data)
However, when I enter this code, R starts processing it for 20 minutes and doesn't respond. Am I doing something incorrectly?
|
I have a variable with some missing values
a <- rnorm(100);
a[sample(1:100,10)] <- NA;
a;
How can I fill missing values with previous non missing value?
for example if I have sequence:
a<- (3, 2, 1, 6, 3, NA, 23, 23, NA);
first NA should be replaced by first previous non NA number 3, second NA should be replaced with ... |
I am using singular vector decomposition on a matrix and obtaining the U, S and Vt matrices. At this point, I am trying to choose a threshold for the number of dimensions to retain. I was suggested to look at a scree plot but am wondering how to go about plotting it in numpy. Currently, I am doing the following using n... |
I plot something to make a point to myself or someone else. Usually, a question starts this process, and often the person asking hopes for a particular answer.
How can I learn interesting things about the data in a less biased way?
Right now I'm roughly following this method:
Summary statistics.
Stripchart.
Scatter p... |
Is it possible to perform a statistical test to determine if one classifier is better than the other using only the confusion matrices of these classifiers?
What about the average accuracies from k-fold cross validation?
I have a number confusion matrices and average accuracy for classifiers obtained through k-fold c... |
I am a thesis student. I conducted an experiment on three different schools. I took a class from each school and assumed that they are one group. I took one group and considered it as a control group. I used paired t test.
The reader in my defense considered that I can't assume that students from each school as one g... |
To make clear what I want to ask, I want to begin with the negative binomial distribution. The first two moments are $E(y)=\mu$ with variance $Var(y)=\mu+\mu^2/k$. When we solve the scorefunction of the log-likelihood with an iterationalgorithm, we get an estimator for $\widehat{\mu}$ (because of the estimator of $\wid... |
I'm interested in an estimator of the standard deviation in a Poisson regression. So the variance is
$$Var(y)=\phi\cdot V(\mu)$$
where $\phi=1$ and $V(\mu)=\mu$. So the variance should be $Var(y)=V(\mu)=\mu$. (I'm just interested in how the variance should be, so if overdispersion occurs ($\widehat{\phi}\neq 1$), I do... |
Suppose I've data for 100 individuals for 5 variables, say Var1, Var2,...Var5. I run the cluster analysis using these 5 variables on these 100 rows & got 3 clusters. Now, I want to differentiate these 3 clusters based on 5 variables. That is, which among these 5 variables has been loaded more for which cluster, in orde... |
I want to do a meta-analysis with count data for treatement/control cases (abundance of sea polichaetos). My problem is that I need to use zero values (an informative zero value) for the mean and standard deviation for one of the treatement, but R has a problem: "Studies with zero values for sd.e or sd.c get no weight ... |
I read from my textbook that $\text{cov}(X,Y)=0$ does not guarantee X and Y are independent. But if they are independent, their covariance must be 0. I could not think of any proper example yet; could someone provide one?
|
I am trying to generate random samples from a custom pdf using R. My pdf is:
$$f_{X}(x) = \frac{3}{2} (1-x^2), 0 \le x \le 1$$
I generated uniform samples and then tried to transform it to my custom distribution. I did this by finding the cdf of my distribution ($F_{X}(x)$) and setting it to the uniform sample ($u$) an... |
This will sound weird, but I'm trying to calculate something that I don't know the name.
I want to calculate how big/low a variable is in relation to the others. Like Google webmaster tools says "your site loads in 3s, this is slower than 59% of sites". How can I calculate this?
For example, the points a player has. He... |
I am trying to perform document-level clustering. I constructed the term-document frequency matrix and I am trying to cluster these high dimensional vectors using k-means. Instead of directly clustering, what I did was to first apply LSA's (Latent Semantic Analysis) singular vector decomposition to obtain the U,S,Vt ma... |
What is the limit to the number of independent variables one may enter in a multiple regression equation? I have 10 predictors that I would like to examine in terms of their relative contribution to the outcome variable. Should I use a bonferroni correction to adjust for multiple analyses?
|
I want to generate two variables. One is binary outcome variable (say success / failure) and the other is age in years. I want age to be positively correlated with success. For example there should be more successes in the higher age segments than in lower. Ideally I should be in position to control degree of correlati... |
I have few training on Hidden Markov Model. But, I intend to solve my problem by HMM. I would like to have your helps/directions to me.
Here, I have two variables to define the 8 one-dimension space (coordinate.1, coordinate.2). In this one-dimension space, there are two sequences of values (shared and specific). This ... |
I was not sure where to put this question, so I put it here. Feel free to move it to another stack exchange site moderators.
Lets say I have a 10 gigs of pictures (or for that matter any type of data, please don't answer the question specifically relating to pictures). Let's pretend that I have the fastest computer in ... |
Given a data scatterplot I can plot the data's principal components on it, as axes tiled with points which are principal components scores. You can see an example plot with the cloud (consisting of 2 clusters) and its first principle component. It is drawn easily: raw component scores are computed as data-matrix x eige... |
I'm interested in plotting the estimator of the standard deviation in a Poisson regression. The variance is $Var(y)=\phi⋅V(\mu)$ where $\phi=1$ and $V(\mu)=\mu$. So the variance should be $Var(y)=V(\mu)=\mu$. (I'm just interested in how the variance should be, so if overdispersion occurs $(\hat{\phi} \ne 1)$, I don't c... |
I'm getting confused with the analysis of one of my experiments. Here is how the results look like.
There were P participants in the experiments and they were split into two groups P1 and P2. Every student had to generate some events E for a set of steps S. Based on this I could count the quality of the answer for ever... |
Recently I am conducting a research on the relationship between motivation/attitude variables (Gardner's model) and English language proficiency in the Philippines. I encountered a problem: missing values. I used a 160-item scale in my study, consisting of around 10 subscales, where each item has a 7-point Likert-type... |
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