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Say I have an observed data set ($n_i$) and I want to obtain the best fit out of 10 data sets produced by a model dependent on a single parameter $a$ ($m_i(a)\;a=1..10$).
Suppose I use a Poisson likelihood distribution:
$P_i(a)=\frac{m_i(a)^{n_i}}{e^{m_i(a)}n_i!}\; ; \; a=1..10$
where $m_i(a)$ represents the model val... |
I am working on my master thesis at the moment and planned on running the statistics with SigmaPlot. However, after spending some time with my data I came to the conclusion that SigmaPlot might not be fit for my problem (I may be mistaken) so I started my first attempts in R, which did not exactly make it easier.
The p... |
I have run
'fitdistr(mydata, "Gaussian")'
and get the following error message:
Error in optim(x = c(34.513, 25.587, 18.251, 52.836, 38.206, 42.395, 47.22, :
initial value in 'vmmin' is not finite
However when I run
'fitdistr(mydata,"Normal")'
I get the following:
mean sd
39.71581691 23.... |
I have two probabilities $p$ and $q$. $p>q$, and they aren't correlated. I'm going to calculate $i$ such that $p^i=q$, which is easily done as $\log_p(q)$.
Now, I'd like to also calculate a confidence interval for $i$, which is necessarily going to be a function of both $p$ and $q$'s confidence intervals. My first appr... |
I have lately been reading papers regarding Sentiment Analysis, where most researches report that their improvements made them achieve an increase of 1~2%, or even 0.5% in accuracy compared to baseline (non-trivial) methods.
Of course, I understand that such an increase (even if small, if statistically significant) ... |
There are several math-heavy papers that describe the Bayesian Lasso, but I want tested, correct JAGS code that I can use.
Could someone post sample BUGS / JAGS code that implements regularized logistic regression? Any scheme (L1, L2, Elasticnet) would be great, but Lasso is preferred. I also wonder if there are intere... |
How does one interpret and generate bean plot charts. Here is one example taken from Walkes et al. 2010. What kind of data is it most useful for?
(source: biomedcentral.com)
|
I have a very simple multinomial logistic regression problem; it's a simplified version of the alligator lake/food/size BUGS example. In my case I have (effectively) lake/food and have just stripped down the alli.bug example to handle two dimensional information: worker and IP address. There are 18 categories of 'work... |
I am trying to construct a bayesian network which detects fraud. I have got a huge data set, with elements such as country, top spend merchant just to name a couple. The first part of my problem is to use a test set of data which is about 11,000 rows in excel and use this to firstly use Bayes formula to see the $P(\tex... |
Let $Q_p$ be a class of probability distributions on non-negative reals parametrized by $p$, so that
$$
Q_p([0,\infty)) = 1.
$$
I wonder which known classes of distributions are closed under taking the maximum and, i.e. if $X_1\sim Q_{p_1}$ and $X_2\sim Q_{p_2}$ are independent then $\max(X_1,X_2)\sim Q_{p_3}$.
|
I recently read a fascinating article describing methods for clustering data without assuming a fixed number of clusters.
The article even includes some sample code, in a mix of Ruby, Python, and R. However, the meat of the analysis is performed using scikit-learn's Dirichlet Process Gaussian Mixture Model to actually... |
I have some data which works nicely with JMP's canned linear discriminant analysis (LDA), but after reading about LDA I'm not sure if the analysis is valid. The Wiki article notes a fundamental assumption of LDA is that independent variables are normally distributed. Does this also mean that I cannot use LDA if my va... |
I'm a little confused about the analysis of normality in a repeated measures ANOVA I'm doing. It's a factorial ANOVA with three rm IVs each of which has only 2 levels. I've read in a few places online and in a book or two that to assess normality in a repeated measures ANOVA, I look at the distributions within each con... |
Suppose I have some some response variable $y_{ij}$ that was measured from $j$th sibling in $i$th family. In addition, some behavioral data $x_{ij}$ were collected at the same time from each subject. I'm trying to analyze the situation with the following linear mixed-effects model:
$$y_{ij} = \alpha_0 + \alpha_1 x_{ij}... |
I am trying to solve this question:
Build a CF-tree for the subset of points, (3,3) (4,3) (6,3) (7,4) (7,5)
assuming that the branching factor, B, is set to 2, the maximum number of sub-clusters at each
leaf node, L, is set to 2 and the threshold on the diameter of sub-clusters stored in the leaf nodes is 1.5.
I have g... |
I am currently using different procedures to estimate the probability that a $D$-dimensional Gaussian random variable with mean $\mu$ and covariance $\Sigma$ lies within a sphere of radius $R$ that is centered about the origin. That is, I am estimating $P(|| X ||_2 < R)$ where $X \sim N(\mu, \Sigma)$ and $X \in \m... |
I have data sets of network traffic that exhibit strong diurnal effects making them non-stationary. One of the analysis that I want to run is to show correlation between days. If we chopped up the time series into individual days, how would I
...show the individual time series are stationary? Would applying Augmented ... |
Twenty possible predictor variables in data set. One outcome variable.
Some of the predictor variables are not linear. So a standard linear multiple regression approach probably won't do. (And I do not want to transform the variables using some arbitrary "cubic," "quadratic" approach -- leave the underlying variable... |
What (with justification) is a valid post-hoc for a two-way ANOVA main effect, if no interaction is present?
Example two-way fixed effect ANOVA:
> aov.example <- aov(Response ~ IV1 * IV2, data=data)
> summary(aov.example)
Df Sum Sq Mean Sq F value Pr(>F)
IV1 1 13.10 13.099 0.7222 0.405... |
In a regularized linear regression model (e.g., ridge regression, lasso, etc.), what is the best way to obtain standard errors for parameter estimates? If cross-validation is used, is it statistically sound to estimate the standard error for each parameter as the standard deviation across folds?
|
Possible Duplicate:
Rank ordering and/or classification problem
Suppose I have ordered objects for some queries.
Q1: o1,o2,o3,o4,o5
And I have learning to rank classifier which can be trained on data best from the list i,e,
o1 is better then o2,o3,o4,o5.
o2 is better then o3,o4,o5.
What is the best way to convert 1s... |
I am doing multinomial logistic regression.
Dependent variable is categorical with 6 categories. 6 Independent variables are measured on an interval scale (included as covariates in SPSS)
Now I am watching the LR test. None of the independent variables have a $\chi^2$ value and no degrees of freedom are shown, so signi... |
Assume a set of nodes is scattered over a 2D surface $\mathcal{S}$ so that for any given $\mathcal{A} \subset \mathcal{S}$, the number of nodes inside $\mathcal{A}$ follows a Poisson distribution with parameter $|\mathcal{A}| \rho$, where $|\mathcal{A}|$ shows the area of the subset $\mathcal{A}$ and $\rho$ is the inte... |
I'd like to perform some statistical methods on data describing the quality/strength of institutions for countries in the world.
I've been searching for this data on the World Bank, OECD, United Nations and IMF.
I must have missed this index, as I've heard about people using it from a respectable source like those ment... |
I have a traditionally structured data set where rows are observations and columns are variables. There are only a few observations but comparatively more variables. The observations are regions of a country and the variables are characteristics (i.e., population size, mean income, number of males, number of females, e... |
I have a document corpus and I want to estimate the probability of occurrence of a certain word $w$. Simply calculating the frequencies and use such a number as an estimation is not a good choice. Is there any work on this topic describing a better approach?
|
Vehicles in a certain country are required to be assessed every year for road-worthiness. At one vehicle assessment center, drivers wait for an average of 15 minutes before the road-worthiness assessment of their vehicle commences. The assessment takes on average 20 minutes to complete. Following the assessment, 80% of... |
Does anyone here know the exact definition of Profile Likelihood? Or does it have one?
|
Is it meaningful to compare the coefficients of two different predictors in multilevel model when the two are at different levels?
Specifically I have two variables which measure the same construct at two different levels (individual and group). I am using R package nlme to fit a multilevel model and want to test the ... |
While reading a textbook on regression I encountered the following paragraph:
The least squares estimate of a vector of linear regression coefficients ($\beta$) is
$$ \hat{\beta} = (X^{t}X)^{-1}{X^t}y $$
which, when viewed as a function of data $y$ (considering the predictors $X$ as constants), is a linear combination... |
In the mixed effect model, many statisticians would like to simulate or bootstrap data to create empirical confidence regions for fixed effect parameters and random effect parameters.
Resampling (ie bootstapping) seems intuitive for me because it makes few assumptions about the nature of the data.
As an alternative, ... |
I ran lm() on my data with models selected by individual lm's of each characteristic and then combined the top $R^2$ based on $p$-value. For instance, the first few characteristics are taken, then the rest are evaluated if they have $p<.005$. My characteristics contain some duplication: for instance, I have a character... |
I'm currently reading Kruschke's excellent "Doing Bayesian Data Analysis" book. However, the chapter on hierarchical logistic regression (Chapter 20) is somewhat confusing.
Figure 20.2 describes a hierarchical logistic regression where the Bernoulli parameter is defined as a the linear function on the coefficients tran... |
What will be the easiest way to compare the derivations (clinical parameters) from two contingency tables? I want to test two 2x2 tables with their respective True Positive, True Negative, False Positive and False Negative entries ($H_0$: Table 1 = Table 2 vs. $H_1$: Table 1 ≠ Table 2). I want to compare statistically ... |
Let's suppose we are attempting to predict traffic accidents on some highway. Traffic Accidents would be the response variable in our data set.
We have TWO competing models:
Two predictor variables: "Time of Day" and "Total Number of Cars Passing Particular Point Per Minute"
Two predictor variables: "Precipitation Le... |
I need to choose a non linear regression model for this kind of data
The experiment was a time course, for a drug, so I get phosphorylation response behaviour in time
In enzyme kinetics or a binding non linear regression model, you do not take into account time, instead you plot the substrate concentration Vs Vmax or r... |
Let $Y=(Y_1,Y_2,\ldots,Y_n)^{T}$ and $Y_1,\ldots,Y_n$ are independent normal random variables with mean $0$ and variance $ \sigma^2$. Find the distribution of the following statistics and give your reasons
a) $T=\displaystyle \sum_{i=1}^{6}(Y_i-\overline{Y})^2$
b) $U =\displaystyle\frac{\sqrt{5}\times Y_6}{\sqrt{Y_{1... |
Given that $Y_1, \ldots, Y_6$ are independent normal random variables with mean $0$ and variance $\sigma^2$. Find the distribution of the following
$ T=\displaystyle\frac{Y^2_{1}+Y^2_{2}+Y^2_{3}}{Y^2_{4}+Y^2_{5}+Y^2_{6}} $
|
I know there are different versions of the central limit theorem and consequently there are different proofs of it. The one I am most familiar with is in the context of a sequence of identically distributed random variables, and the proof is based on an integral transform (eg. characteristic function, moment generating... |
I've used the Mann-Whitney U-test in order to check for possible differences between two relatively small groups (12 subject in each) on 15 different items. I didn't have any pre-defined assumption about which items would be different. However this simple Mann-Whitney U-test yielded a significant different (P<0.05) fo... |
I've been studying discrete time series models for a while. I'm familiar with the usual time series models (ARMA, ARIMA, GARCH, etc.), but I want to study their continuous counterparts (CAR and CARMA processes seem very interesting) in order to implement some models to unevely spaced time series.
Despite of the above,... |
How would you test or check that sampling is IID (Independent and Identically Distributed)? Note that I do not mean Gaussian and Identically Distributed, just IID.
And idea that comes to my mind is to repeatedly split the sample in two sub-samples of equal size, perform the Kolmogorov-Smirnov test and check that the di... |
How can I look for collinearity diagnostics, particularly condition indexes and proportions of variance in Multinomial logistic regression?
|
I can't fit $X$ to a common distribution so currently I just have $X \sim \text{ecdf(sample_data)}$.
How do I calculate the empirical distribution of $\sum(X_1 + ... + X_n)$, given $n$? $X_1$ to $X_n$ are iid.
My sample size is around $6\times10^7$. $n$ needs to be around 10-20.
To give an example of what I am doing: S... |
I am taking a course on Maximum Entropy Inference (MEI), where its application to k-Means was discussed. I am confused about the problem setting.
As far as I understand, our goal is to find clustering solutions $c(\cdot)$ with small expected cost $\mathbb{E}[R^{km}(c)] \le R_{max}$. We are therefore interested in sampl... |
This article uses the following form of the chi-squared test:
$\chi^2=\sum\limits_{i}\frac{(m_i-n_i)^2}{m_i+n_i}$
where $m_i$ is the number of counts of bin $i$ in a modeled histogram and $n_i$ the equivalent for the observed histogram.
How does one obtain this form of the $\chi^2$ test?
Is this a non-parametric stati... |
I have some experimental data, and I want to use a non-parametric test to verify my results. I am considering link-prediction on complex networks.
I have a complex network $N$ and an algorithm/model $A$ which finds structure in $N$. I then remove some of the edges in $N$, first $10\%$, then $30\%$ up to $90\%$. For eac... |
I'm not a statistician, so I hope this question makes sense. I'm an EMT and we have patients known to be "frequent flyers". Example, we have a diabetic that we have seen 100+ times in 3 years. I have looked over his pattern of calls and it looks like they follow an exponential distribution, which makes sense to me. How... |
I have a (mixed) model in which one of my predictors should a priori only be quadratically related to the predictor (due to the experimental manipulation). Hence, I would like to add only the quadratic term to the model. Two things keep me from doing so:
I think I read somehwere that you should always include the lowe... |
I am using the randomForest package in R (R version 2.13.1, randomForest version 4.6-2) for regression and noticed a significant bias in my results: the prediction error is dependent on the value of the response variable. High values are under-predicted and low values are over-predicted. At first I suspected this was a... |
I once read (unfortunately I cannot find the source anymore) that oversampling is only "allowed" when the class distribution is very, very skewed, i.e. 1:99 or worse.
So in my case I have a class distribution of 30:70. When don't apply oversampling in my neural network (10-20-1, sigmoid (hidden layer), softmax(output... |
I have time series as
0.4385487 0.7024281 0.9381081 0.8235792 0.7779642 1.1670665 1.1958634 1.1958634 0.8235792 0.8530141 0.8802216 1.1958634 1.1235897 1.3542734 1.3245534 0.9381081 1.1670665 1.1958634 0.8802216 1.3542734 1.1670665 4.9167998 0.9651803 0.8221709 1.1070461 1.2006974 1.3542734 0.9651803 0.9381081 0.96518... |
I have a data set which is highly imbalanced and I have used the SMOTE algorithm (using the R package DMwR) to balance the binary class in the data set. I have been using the R Ada package to then train an Ada Boost model on this data set to predict the binary class, with very good results.
In the same data set, I have... |
What is the state-of-the-art in the efficient computation of smoothing splines?
The algorithm I see mentioned most often is that of Reinsch, dating back to 1967. As I understand it, the most expensive part is performing a Cholesky decomposition. What other algorithms for smoothing splines have there been since then?
|
This is a very simple question but I can't find the derivation anywhere on the internet or in a book. I would like to see the derivation of how one Bayesian updates a multivariate normal distribution. For example: imagine that
$$ \begin{array}{rcl}
\mathbb{P}({\bf x}|{\bf μ},{\bf Σ}) & = & N({\bf \mu}, {\bf \Sigma}... |
What is the advantages of the ROC curves?
For example I am classifying some images which is a binary classification problem.
I extracted about 500 features and applied a features selection algorithm to select a set of features then I applied SVM for classification. In this case how can I get a ROC curve?
Should I chang... |
Here is a probability problem: you observe .5 cars on average passing in front of you every 5 minutes on a road. What is the probability of seeing at least 1 car in 10 minutes?
I'm trying to solve this in 2 ways. The first way is to say: P(no car in 5 minutes) = 1 - .5 = .5. P(no car in first 5 minutes and no car in se... |
What are some examples of less common transformations or basis expansions that have been applied to a set of input variables to build a more complex linear regression model?
For example, a "common" transformation might be to include a set of interaction predictors; a "less common" transformation might be to cluster t... |
I have two datasets a training and a test dataset. The dependent variable is a proportion and there are 54 predictors which are positive and negative real numbers and another 7 predictors that are text.
There are three response variables. Total the normalized total number of hits. Treatment the normalized total number... |
Based solely on the temporal pattern of mouse clicks (a list of click times $[t_1,t_2,t_3,\ldots]$), is it possible to predict the computer user's activity?
For example out of: working vs spending time on Facebook vs watching photos vs playing a computer game.
If they are any more fine-grained predictions (e.g. playing... |
I am working on reducing the data from a particular type of particle detector. When struck by a particle, this detector produces a voltage pulse that has the form of a Gaussian convolved with an exponential decay.
Among the earlier work done with this sort of detector, I've found one journal article which suggests that... |
I have some data about two machines, each machine has 10-15 operation logs, and inside the log are the time-stamped status checks that takes on the value of 1 if there is a warning and 0 otherwise.
The question is to decide which machine is better? (in terms of less warnings in the log)
I am thinking of the two approac... |
What methods are there to fit a model of the form $y=A\mathrm e^{Bx}+C\mathrm e^{Dx}+E$?
Here is the actual scientific data to be fitted: http://dl.dropbox.com/u/39499990/Ben%2C%20real%20data.xlsx
B should be in the range of -1 to -100.
D should be in the range of -100 to -500.
E is a constant.
This specific model is ... |
I have a question for graph machine learning gurus :). For this project I'm working on, I need to be able to learn similarity between typed graphs. By typed I mean that every vertex and every edge of the graph has it's type. Also, both nodes and vertices can be attributed (assigned with some "key-value" attributes).
No... |
What are the pros and cons of segmented regression and regression with ARIMA errors for interrupted time-series analysis?
In what situation would I choose one method over the other? Are there any papers comparing the two techniques?
|
I have the following time series
1.3578511
0.5119648
1.3189847
0.9214787
1.2272616
4.9167998
1.2272616
1.2272616
0.8854192
2.3386331
1.6132899
0.2030302
0.8426226
1.2277843
NA
1.3189847
1.3578511
0.8530141
2.3386331
1.0541099
0.7747481
0.5764672
1.3189847
1.2160533
1.2272616
0.6715839
0.9651803
1.6132899
1.2006974
0.68... |
I apologize in advance for the "how do I run this model in R" question, but it turns out that's the shape my problem has assumed :-). Hopefully I have enough substantive questions surrounding it to be interesting, and the question will come out more like, "Does this command in R correspond to this statistical model?"
... |
Does there exist a positive-only distribution such that the difference of two independent samples from this distribution is normally distributed? If so, does it have a simple form?
|
In the one-dimensional case it is easy to obtain random numbers that are not too far away from the mean by checking if they are within one or two standard deviations. Is there some similar way to obtain random numbers that are not to far away from the mean vector of a multivariate normal distribution?
Thank you very mu... |
I'm working on multivariate process monitoring using NLPCA method.
I need MATLAB code to implement this method.
|
I remember reading about a general rule of thumb for choosing number of features. It was something like $\sqrt{\log_2(n)}$, where $n$ is the number of samples or $\log_2(n)$. Does anyone remember the original paper (or book) that describes the formula?
Alternatively, could you kindly describe a good guideline to derive... |
Say I have a vector of length 1000. At each position (1 ... 1000) there is a count. I have two vectors with different range of counts such that in vector A the maximum number of counts at a position is 30, whereas in vector B the maximum is say 200 (i.e., there are more counts in B than A).
So essentially I have two d... |
I have been reading some papers regarding statistics and I seem to be confusing the terms priors and likelihood.
Would it be possible to explain the difference between the two terms? I am interested in both a "down-to-earth" approach with examples and the mathematical and statistical aspects.
Thanks.
|
I'm not really "into" statistics, so I could use a hand on this one. I have two small groups, one has 12 students and the another one has 6.
Both groups answered a questionnaire and I'm trying to find out which of the groups did better. I'm not sure if I should be using the average of correct answers to do this compari... |
I would like to get help from an expert or anyone who knows about this. As a beginner in SPSS, I've googled the steps to do multinomial regression. I've decide to use multinomial because from what I googled and understood, binomial is for situations that only have 2 categories like yes or no, which you could code 0 f... |
Body mass index was compared for two groups, people with elevated triglycerides (above 1.7 mmol/L) and people with normal triglyceride levels. The 10 people in the group with elevated triglyceride had body mass index mean = 26.1 and standard deviation = 3.72 and the 15 people in the normal group had body mass index mea... |
What options are available for smoothing 2-dimensional real data for which the the ordinate points are real intervals of the form
$(x_j , [y_{j0} , y_{j1}])$
In my case, the data is vague because of intrinsic measurement precision, and I want the knowledge of the quantity to be characterized by a uniform distribution o... |
I started to play with naiveBayes function from e1071 package. It looks simple on small test examples. But it performs poor on my actual task. I have ~4000 observation belonging to 2 classes and described by ~19000 numeric variables. The entire dataset was split on training and test sets, and naiveBayes model have been... |
A question was asked whether or not two independent variables $X$ and $Y$ that take on only positive values can have $X-Y$ be a normal distribution. I was shown that the answer is no. But I think that this can be done with two half normals that are dependent. But I could not quite figure out how to structure the dep... |
I need to make a histogram of employees in firms across the country.
My goal is to examine the extreme observations and there is of course a lot in the beginning and very few in the end so I can't figure out how to make one histogram give a clear vision of both how large the extremes are and how many there are in the a... |
I have created a multiple linear regression model with R using lm and glm. I am using lm on a training set and predict on a testing set to validate the model. In one test my results are within 80% of what they should be for 80% of the cases. It correlates with 40% for one response variable and with 63% for another resp... |
Which article should I reference as a source of the following claim?:
The $\chi^2$ test is not recommended when too many sparsely populated bins exist in a given histogram.
Please rephrase the above sentence if it is not clear.
This article (page 328) by W. Cochran states something along that lines, but it's pretty old... |
This question was originally asked by a colleague with regards to calculation of AIC for a non-linear mixed effects model (nlme) where off-diagonal elements of the covariance matrix are estimated. The equations for AIC (from Wikipedia):
\begin{align}
AIC &= OFV + 2k \\
BIC &= OFV + k \ln(n)
\end{align}
with $k$ ... |
I've been playing around with fitting nonlinear models using rjags. Specifically 3 and 4 parameter sigmoid curves, e.g.,
upAsym + (y0 - upAsym)/ (1 + (x[r]/midPoint)^slope))
I've noticed that good parameter estimates (+- 95% HDIs) are highly dependent upon having tightly constrained priors. Are there any good guidel... |
Is there an R random forest implementation that works well with very sparse data? I have thousands or millions of boolean input variables, but only hundreds or so will be TRUE for any given example.
I'm relatively new to R and noticed that there is a 'Matrix' package for dealing with sparse data, but the standard 'rand... |
Wikipedia says in binary classification:
Tests whose results are of continuous values, such as most blood
values, can artificially be made binary by defining a cutoff value,
with test results being designated as positive or negative depending
on whether the resultant value is higher or lower than the cutoff.
Is... |
Possible Duplicate:
How can adding a 2nd IV make the 1st IV significant?
I am looking at the prediction of relapse by gender.
In a hierarchical log regression, with gender entered in first block, it is significant. When anxiety is entered in second block, both anxiety and gender are insignificant. Interaction terms... |
Study Design: I have a 2x3 factorial design, 2 levels of Time (2050 or 2100) by 3 levels of information (None/Control, Moderate, Extreme).
I set up some very specific contrasts when analyzing this design, in particular Control vs. Other, Moderate vs. Extreme, and 2050 vs. 2100. For one DV, the overall ANOVA was not sig... |
I'm interested to know what a good practice is when generating/simulating data for testing or comparing modelling methods. I'm focusing on linear models and measuring prediction accuracy and measuring parameter estimate accuracy.
I'm looking at prediction accuracy (PSE) in terms of cross validated squared prediction er... |
Suppose we are given a set of data of the form $(y,x_{1},x_{2},\cdots, x_{n})$ and $(y,x_{1},x_{2},\cdots, x_{n-1})$. We are given the task of predicting $y$ based on values of $x$. We estimate two regressions where:
$$
\begin{align}
y &=f_{1}(x_{1},\cdots, x_{n-1}, x_{n}) \tag{1} \\
y &=f_{2}(x_{1},\cdots, x_{n-1}) ... |
Possible Duplicate:
Goodness of fit test for a mixture in R
I just estimated the parameters for a mixture of two gaussians with different means and different sigmas, I would like to test if the data adjusts well to the explicit form of the mixture, do I necessarily need to simulate data from the mixture or how can I... |
I have adjusted the parameters (lambda, mu, sigma) for a mixture of two normals fitted to my data. Now I would like to plot the cdf of this model using the explicit function instead of the ecdf. Is there any way to do this or I do I have to simulate data so then I can use again ecdf?
The explicit function is something ... |
I am writing a program to predict the click through rates of online ads. Two important notes about this problem:
click through rates are very small (like 0.1%)
click through rates depend on several parameters (like size of the ad, country in which ad is shown, whether the user has seen this ad earlier etc)
As I emplo... |
I'm dealing with a supervized binary classification issue. My dataset is composed of 1500 individuals, living in 600 households. I have approximately 4000 variables to classify my subjects as "infected/uninfected".
I was wondering how would it be possible to account for the hierarchical nature of my data in a data min... |
What's the best way to study the association between nominal response (3 non-ordered categories) and one ordinal predictor variable (most observations are interval scaled, but some are censored (only known to be above x)) in smallish sample (50).
I think that Mantel-Haenszel row means score test (SAS) might be appropri... |
I have downloaded the sample codes from kaggle for the randomForest benchmark [URL?] and there's this part that I don't understand.
appendNAs <- function(dataset, cols) {
append_these = data.frame( is.na(dataset[, cols] ))
names(append_these) = paste(names(append_these), "NA", sep = "_")
dataset = cbind(dataset... |
I need to utilize two different classifier to get best classification results. Since, it seems that they complement each other (not sure I am not expert btw). ROC characteristics are given below (testing scheme is 10-fold cross validation):
MetaCost [0 8; 1 0] Alternating Decision Tree (ADTree)
TP Rate ... |
I want to know how random variables at a certain geographic location are correlated spatially. Lets say I have a certain function z depending on the spatial locations of the points. If I plot this z values spatially, then from the plot how can I analyze their spatial correlation. How does the plot look like or supposed... |
Suppose we want to cluster a data stream of unknown number of clusters, and estimate them using particle filters. With particle filters, we need to know $P(x_t | x_{t-1})$ and $P(z_t | x_t)$ (where z refer to the data (reports), and x refer to the estimated states (hypothesis)).
Then my question is: how can we define $... |
I just estimated the parameters for a mixture of two gaussians with different means and different sigmas, I would like to test if the data adjusts well to the explicit form of the mixture, do I necessarily need to simulate data from the mixture or how can I test the goodness of fit? I am using the mixtools package.
|
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