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I am pretty new to clustering, so please be patient.
I have a set of points, and each point has a weight. I need to group these points into N clusters (N is defined).
I need these clusters to satisfy two conditions:
The points of a cluster must be spatially connected.
If a cluster has points with high weights, it must... |
I had eleven people play five versions of a video game in single sessions, for a total of 55 sessions (11x5). I used the Task Evaluation Questionnaire from the Intrinsic Motivation Inventory to capture their experiences.
Do I need to test the reliability and validity of this survey for the data that I collected? Someon... |
I am trying to predict the future performance of customers on one of the websites I run. We provide practice tests leading up to a final exam, taken elsewhere. Based on the user's answer to multiple questions (only counting the first time they see the question), I am hoping to predict if they will pass their final exam... |
How do I decode NOAA TREND files such as:
ftp://tgftp.nws.noaa.gov/data/observations/metar/trend/KABQ.TREND
I know how to decode METAR, SYNOP, SHIP, and BUOY files, but not these.
[is there a better place to post this?]
|
How can I fill with a color in one side of the diagonal of the following graph (only one triangle area) in R? I have used abline(0,1) for drawing the diagonal line. However, as we can see the the diagonal line is not perfect in the left-bottom corner. Could someone help me to draw a perfect diagonal line that starts ex... |
I have a matrix with two columns that have many prices (750).
In the image below I plotted the residuals of the follow linear regression:
lm(prices[,1] ~ prices[,2])
Looking at image, seems to be a very strong autocorrelation of the residuals.
However how can I test if the autocorrelation of those residuals is strong?... |
Pattern classification by Duda, Hart, Stork (Section- 9.6.8) states that a 2-class training set of $d+1$ or less samples in a d−dimensional space is always linearly separable i.e. if the samples span the $d$ dimensions and not in any sub-space of $d$.
In short, for $n \le d + 1$, where $n$ is the number of samples, the... |
I ran into the following problem while using transcan() function from the rms package. For a fixed dataset, I ran transcan() to transform a set of 15 variables on 2 separate Linux machines - the final transformations were exactly inverses of each other, i.e. T1 = C-T2, where C is a constant. I am sending you plots show... |
I'm very new to SAS, so please keep that in mind with any responses.
I've been running the following code in SAS:
FILENAME fishfile URL
"http://www.amstat.org/publications/jse/datasets/fishcatch.dat";
PROC FORMAT;
VALUE sexfmt 0="female" 1="male";
VALUE speciesfmt 1="common bream" 2="whitefish" 3="roach"
4="si... |
When I perform a linear regression in some software packages (for example Mathematica), I get p-values associated with the individual parameters in the model. For, instance the results of a linear regression that produces a result $ax+b$ will have a p-value associated with $a$ and one with $b$.
What do these p-values... |
I have a random variable $x$ with $E(x) = \mu$ and PDF $f(x)$ and CDF of $F(x)$.
Is there any way to represent the $E(x|x<\bar{x})$ in terms of $\mu$ and $f(x)$ or $F(x)$?
i.e. to write the following integral only in terms of $\mu$, $f$ and $F$:
$$
\int_{-\infty}^\bar{x} x f(x) dx
$$
Thanks
|
I am a newbie in R programming. I think for most of you my question is a rather simple one. My regression problem is as follows:
I have a dataframe containing several numerical attributes and several factors, which are different in the number of levels. I split the dataset in a training set and a test set. I will use ... |
The short version of my question is: How is it possible to control for a confounding variable that has a Dirichlet distribution?
Suppose I have electoral and census data for a large set of cities. In this simplified example, say, there are two parties (Liberal and Conservative), and that someone is either college educa... |
Hi in base graphics in R, I would like to overlay a bar plot on a chart which has irregularly spaced points on a curve. The bars should represent the change in these points since the previous sample. But I would like the bars to align to the points in the horizontal direction, so there should basically be a lot of whit... |
I'm writing code to approximate a function $y=f(\vec{x})$ where $y\in\mathbb{R}$ and $\vec{x}\in\mathbb{R}^N$ for medium-sized $N$ ($N$ between 20 and 50, approx.). I have a ton of examples, however, so my number of examples greatly exceeds $N$. But, the examples probably are somewhat redundant, and some of the $N$ v... |
I am trying to run a repeated measures Anova in R followed by some specific
contrasts on that dataset. I think the correct approach would be to use
Anova() from the car package.
Lets illustrate my question with the example taken from ?Anova using the
OBrienKaiser data (Note: I ommited the gender factor from the example... |
I have a seasonally decomposed data set. The data set has strong seasonality.
Now I am trying to fit the 'seasonal part' of dataset into ARIMA model and tried to forecast (with SPSS).
The problem is, I get exactly same values in forecasts as that of actual values. So, MAPE is coming to be 0.000
Is this obvious to happ... |
I need to calculate matrix inverse and have been using solve function. While it works well on small matrices, solve tends to be very slow on large matrices. I was wondering if there is any other function or combination of functions (through SVD, QR, LU, or other decomposition functions) that can give me faster results.... |
We are building a score card system to measure the performance of various groups in the organization. The scores are generated by true / false metrics on individual transactions that each group completes.
Transactions are qualified for measurement by some metrics but not others. The number of transactions also varies... |
I need some suggestion for clustering (unsupervised classification) method for a consulting project. I am looking for a method that hopefully has the following properties:
The subject of my study has three properties. One is represented by
a (non-Euclidean) distance matrix and the other two are in the form
of vectors ... |
I want to do price modeling using the Van Westendorp price sensitivity meter.
Can anybody provide me resources describing how to do this using R?
|
I am working on a classification problem using IP addresses as input and I am trying to find which IP addresses or subnets are likely to belong to a spammer. I have data consisting of the four octets in the IP address as well as a label: SPAM or OK.
This feels like a good problem for a decision tree, but I am finding t... |
I want to joint 4 Poisson variables and 1 Bernoulli variable with D-vine copula. How can I do this with R?
|
I use a hexplot to visualize data in R. I'm wondering if I can make the number of the colors of the bins grow.
Let me give you an example:
library(hexbin)
plot(hexbin(rnorm(1000000),rnorm(1000000)))
This creates the following plot:
What I would like to have is smaller step in the colors thus more colors in this pl... |
Firstly, excuse my naivity but I am just starting out in research.
Overview of study
I am doing a project looking at Social anxiety in adolescence and using social network analysis (SNA). I argue that negative peer relations accounts for variance in social anxiety above and beyond individual level characteristics (in t... |
What is an example of an algorithm that, when i have a known distribution across discrete groups and I have some sort of model score that a person is in each group, assigns persons to groups such that the sum of the group scores are maximized, or some other objective criteria is met and we honor the known class distrib... |
Suppose I have measured some variable in siblings, which are nested within families. The data structure looks like this:
family sibling value
------ ------- -----
1 1 y_11
1 2 y_12
2 1 y_21
2 2 y_22
2 3 y_23
... ... ...
I want to know the correlation betwe... |
I have been assigned the task of conducting an annual risk and fraud survey at work. I have a limited statistical background and am not sure what the best way to approach this is. The goal of the survey is to measure the concerns of upper management in different areas that represent risk to the company and also measure... |
When running a repeated measures ANOVA in SPSS, it's possible to 'Save' the residuals as new variables in the data editor.
But the values output do not match the residuals given in R, and seem to be residuals for a between-subjects model. Unless I am missing something? Is SPSS giving the wrong residuals?
Example in R:
... |
I have a real-life problem similar to the following two subproblems, which are about maximizing samples' representativeness (and maybe getting smaller variance than with simple random sampling, but due to the small sample size, the stratification gains cannot be used):
Example 1:
Given is a population of 1000 people, ... |
I'm trying to use the randomSurvivalForest package in R to predict the next event in a series of events (using res <- predict(fit,v)), but all I get is a total % survivors and then the cumulative hazard for each individual in the res$ensemble. Can I use this to predict/generate values matching what's in in res$time?
|
I'm using a maximum a posteriori probability (MAP) estimator in a classification problem. After estimating all the a posteriori probability, the standard way is to simply take the class associated with the maximum probability. I would like to measure the confidence of this decision. I.e. if the maximum a posteriori pro... |
I have $P$ correlation matrices $(n \times n)$ computed with $P$ sets of $(m \times n)$ data (observed) using the MATLAB function corrcoef.
How do I compare and analyze these $P$ correlation matrices with respect to each other?
What are the tests, methods and/or checkpoints?
|
Suppose I have a regression model which yields a couple of predicted values with their respective prediction intervals and the random quantity that I am interested in is the sum of (some subset) of those predicted values. How do I go about building a new prediction interval for this sum? Is it as easy as summing up the... |
Consider the following cell biology experiment. We are comparing $T$ different treatments of cultured cells. Each treatment $t$ is replicated in several (microtiter) wells, indexed by the variable $w \in \{1, 2, \cdots, W\}$. To measure the response to the treatment in well $w$, a total of $F_w$ non-overlapping micr... |
I have around 5 million observations of weights of patients over the course of a year. Some patients have one measurement during that year and others have 30-40 (or more). I've noticed a great deal of variability. For example, on one day a patient will have a recorded weight of 120 lbs and the next a recorded weight... |
I have monthly precipitation for one site over a 35 year period. I would like to test if the total precipitation for a specific year is equal to the mean total precipitation for the rest of the period of record. In addition, I would also like to split the data into wet season [Nov-April] vs dry season [May-Oct].
I re... |
This has come up in a few questions now, and I've been wondering about something. Has the field as a whole moved toward "reproducibility" focusing on the availability of the original data, and the code in question?
I was always taught that the core of reproducibility was not necessarily, as I've referred to it, the abi... |
Borrowing from this post on SAS and R: http://sas-and-r.blogspot.com/2011/07/example-92-transparency-and-bivariate.html
I've got a large collection of data that's best approached (or at least well approached) using some sort of scatter plot with smoothing or binning. R's smoothScatter function works marvelously, but i... |
I am trying to come up with a way to statistically test this question, and could use some input, as it's far afield from what I normally do. I have a hierarchical network, like this one:
And a centrality measurement of each node. What I want to do is test if the measurement for each "layer" (i.e. nodes 1 step from the... |
Suppose I observe independent variable vectors $\vec{x}$ and $\vec{z}$ and dependent variable $y$. I would like to fit a model of the form:
$$y = \vec{x}^{\top}\vec{\beta_1} + \sigma g\left(\vec{z}^{\top} \vec{\beta_2}\right) \epsilon,$$
where $g$ is some positive-valued twice-differentiable function, $\sigma$ is an un... |
Suppose we have two random variables $X$ and $Y$ with unknown distributions. I am looking for an unbiased estimator for the absolute expected difference:
$$
| E \{ X - Y \} | .
$$
For instance, suppose we have unbiased independent observations $x_1, \ldots, x_n$ and $y_1, \ldots, y_m$ ($n,m \geq 1$), how can we use t... |
I'm a novice in statistics and I have some confusion about the assumption of independence for statistical tests.
I searched the Internet and some information says that for the t-test, the observations in the two groups should be independent (that is, measurements in sample 1 and measurements in sample 2 should be dif... |
For a simulation study I have to generate random variables that show a predefined (population) correlation to an existing variable $Y$.
I looked into the R packages copula and CDVine which can produce random multivariate distributions with a given dependency structure. It is, however, not possible to fix one of the res... |
I used a SVM to perform classifications on the same sample and I get the following results:
Good classifications:
baseline : 78%
transformation 1 : 79%
transformation 2 : 63%
I do not know which test to use to tell if the performance difference is significant (ie. is the transformation 1 really better than tra... |
I have three Pearson correlation coefficients (.8978, .5676 and .7865) for three age groups (i.e. 21 to 30 years, 31 to 40 years and 41 to 50 years) whose behavior I am studying in regard to their shopping habits versus weight gain.
Can I say that .8978 is the strongest relationship between shopping habits and weight g... |
I'm familiar with very basic plotting in R, but I'm not sure how best to create the reasonably-complicated plot described below.
I have developed a density estimation method that essentially fits an empirical distribution to multiple univariate samples, under distinct conditions. To be clear, let $\mathbf{x}_i^\mathrm{... |
I've been searching for a way to combine two hazard ratios from the same study for a meta-analysis, but found nothing. Does anyone know how to do this?
Any thoughts would be great.
Good Day,
Simon
|
I have a few (e.g. 10) observations of travel times for a route.
A commuter needs to arrive to his destination before t0 (given).
I want to say: The commuter should depart before t0 - x to arrive to his destination at t0 with probability 95%.
Can I do this just by calculating the sample mean (m) and standard deviation ... |
If I'm using OLS linear regression, and I want to know the uncertainty of my forecasts I can quantify it using residuals (MSE, median absolute deviation, etc). But if I'm using robust linear regression that down-weighs some observations as outliers and I don't have access to those weights, how can I accurately quantity... |
I have the following data:
IV = 2 levels (Experimental Group + Control Group).
DV = I'm using signal detection variables i.e. (Hits, CRs, FAs & Misses)
Both groups were tested twice so therefore I have 2 sets of DVs for each group (i.e. Hits 1 & 2, CRs 1 & 2) and so on.
I want to compare between-group differences as w... |
I am using a particle filter to estimate the parameters($\Phi_{n\times1}$) of a non-linear model. Say my input (observations) is $t=1:k$, I will have a vector of length $k$ for each of the parameter estimates. Thus, at the end of the particle filter, I will end up with a parameter estimate matrix ($\Theta$) of $k\times... |
I want to simulate a user reading a book. The amount of time spent on a page will be random, but subject to a particular distribution, I just don't know which one. A normal distribution has the problem that it can produce negative values, which is clearly not right.
What's the correct distribution for this kind of ra... |
Does anyone know if the following has been described and (either way) if it sounds like a plausible method for learning a predictive model with a very unbalanced target variable?
Often in CRM applications of data mining, we will seek a model where the positive event (success) is very rare relative to the majority (nega... |
I'm taking an intro to marketing class this semester and the course requires us to buy a software which looks nothing more than a bunch of excel macros. From the software's page
Marketing Engineering for Excel provides tools to help address the most common marketing problems Segmentation, Targeting and Positioning (ST... |
I was wondering if there are any well-established or known low-dimensional descriptors (i.e. heuristics or features) for the problem of discriminating periodic 1D signals from aperiodic ones.
My take so far:
I'm thinking there may be ways of compactly encoding the DFT spectrum of the signal if I assume that I can fi... |
I have made non-stationary data stationary by differencing at lag 1 and then differencing the differences at lag 11. The data values for months 1/06 through 6/11 are in an Excel file at https://rapidshare.com/files/3190310580/data.xls, reproduced here:
5821 7652 8761 6578 4320 10982 4522 6573 16... |
First some preamble:
Let A be a set of unordered elements, and let A' and A'' be subsets of A, where |A'| = |A''| = k. It’s given that as k approaches |A|, for every x in A' there is an increased probability of finding x in A''. That is, as k approaches |A|, |A' ∩ A''| approaches |A|.
On to the issue at hand:
Let’s say... |
I´m using the pam() R function to perform clustering. As far as I know, the pamk() function serves as a wrapper to pam(), and evaluates the optimal number of clusters. However, using the same data and parameters I get different results.
For example, calling pamk() and pam() as follows returns 2 clusters with different ... |
I am running an AB Test on a page that receives only 5k visits per month. It would take too long to reach traffic levels necessary to measure a +-1% difference between the test and control. I have heard that I can use Bayesian stats to give me a good chance of determining whether the test outperformed. How can I do use... |
I have a nonlinear model $y=\Phi(f(x,a)) + \varepsilon$, where $\Phi$ is the cdf of the standard normal distribution and f is nonlinear (see below). I want to test the goodness of fit of this model with parameter $a$ to my data $(x_1,y_1),(x_2,y_2),\dots,(x_n,y_n)$, after having used maximum likelihood estimation to fi... |
The title says it all, and I'm confused. The following runs a repeated measures aov() in R, and runs what I thought was an equivalent lm() call, but they return different error residuals (although the sums of squares are the same).
Clearly the residuals and fitted values from aov() are the ones used in the model, becau... |
How to generate distribution in R, members of which are inside bounds and mean with SD are fixed?
I just need a distribution which will fit in the supported criteria. This will be used for simulating results from other study for comparison with data I have.
I need something like this:
rBootstrap<-function(n,mean,sd,low... |
I have the following results from a biological experiment. I measure the size of the sample (2,4,8,16,32 or 64) and count its distribution in a population of 50 (sum of counts=50). I do those measurements in the wildtype (wt) and the experimental sample (KO) in three independent experiments (replicate 1,2,3).
Am I in a... |
I have a binary time series with 1 when the car is not moving, and 0 when the car is moving. I want to make a forecast for a time horizon up to 36 hours ahead and for each hour.
My first approach was to use a Naive Bayes using the following inputs: t-24 (daily seasonal), t-48 (weekly seasonal), hour of the day. Howeve... |
I'm using the changepoint package in R because I need to check if the variance is stable or if there are some breaks inside. The function cpt.var does the job well but there is not a parameter to set the "lags". With lags I mean a parameter to specify how many errors can be accepted before should be consider it a break... |
Q: For which data is it appropriate to use state-space modeling and Kalman filtering instead of smoothing splines and vice versa? Is there some equivalence relationship between the two?
I'm trying to get some high-level understanding of how these methods fit together. I browsed through Johnstone's new Gaussian Estimat... |
My problem is i'm trying to figure out how many servers might be required to handle a theoretical maximal load of data requests. To do that I need to know what the maximum number of requests in a second might be.
I have a fairly limited set of data that 156,000 transactions occurred in one hour. This is the maximum r... |
Gaussian discriminant analysis models learn $P(x|y)$ and then apply Bayes rule to evaluate
$$P(y|x) = \frac{P(x|y)P_{prior}(y)}{\Sigma_{g \in Y} P(x|g) P_{prior}(g) }.$$ Hence, they are generative models. Why then is it called discriminant analysis? If it is because we finally derive a discriminant curve between the c... |
Based on a response to the question "Statistical classification of text", I've decided that I want to use a random forest to perform various classifications of text.
Specifically, I am getting YouTube video data from their XML feeds. Here is an example:
<entry gd:etag="W/"DUQBR347eCp7I2A9WhdXFEQ."">
<id>tag:youtub... |
I see the type parameter for Phillips & Ouliaris Cointegration Test in the urca package that should be Pz or Pu. I read the details, but I don't understand what type is useful for me. If I wanted to check the cointegration with that method for two series of stock prices, what type would be better?
In other words, what ... |
What is the proper way to write a Tukey post-hoc result?
There are several examples with different results?
Say you have North, South, East and West.
North N=50 Mean=2.45 SD=3.9 std error=.577 LB=1.29 UB=3.62
South N=40 Mean=2.54 SD=3.8 std error=.576 LB=1.29 UB=3.63
East N=55 Mean=3.45 SD=3.7 std error=.575 LB=... |
I'm trying to predict the probability that a user will visit a particular website based on several factors (day of the week, time since last visit, etc). My question is what to do if one of the numerator terms goes to zero?
For instance, suppose I visit www.google.com often, but I've never visited on a Monday. $p(Monda... |
I am analyzing survey data for a membership organization. We have survey data from 2000, 2005, and 2010, and each year has between 400-600 respondents (the survey was sent to all members). In all years, the ratio of men to women is highly male, and there are many more people in the upper age categories. However, it see... |
e.g. estimate the probability that of 10 (ten) small businesses 3 (three) or less will fail in the first year of operation
|
If I have a GLM with a number of explanatory variables, where one is a categorical variable with levels "no treatment" "treatment A" "treatment B"
Assuming that it is reasonable to combine the 2 treatment groups together experimentally, what statistical assumptions do I need to check?
I wish to include to include the p... |
I am new in PMML, Predictive Model Markup Language and I was wondering if there is some kind of Java support (Open Source / professional) for creating/parsing PMML files.
Initially I only have in mind the possibility of creating/parsing PMML files programatically from Java environments.
I have been "googling" and I hav... |
I recently realized that a mixed-model with only subject as a random factor and the other factors as fixed factors is equivalent to an ANOVA when setting the correlational structure of the mixed model to compound symmetry.
Therefore I would like to know what does compound symmetry mean in the context of a mixed (i.e., ... |
Given the following experimental setup:
Multiple samples are taken from a subject and each sample is treated multiple ways (including a control treatment). What is mainly interesting is the difference between the control and each treatment.
I can think of two simple models for this data. With sample $i$, treatment $j$,... |
I use a Cox proportional hazard model (coxph()) which gives me HR of about 2.9 for presence of factor B (factors can be A, B, C, A as baseline in the model), with 95% CI 1.8-4.8 , p<0.001.
When checking the proportionality assumption there is significant evidence that there is a violation of that assumption.
Result of ... |
I have a 3 class sample labeled data set, which I have divided into 2 parts. I am using the first part to train the two-class perceptron classifier.
One approach is to train $\binom{3}{2}$ two-class classifiers on training data for two classes at a time, and then use voting to classify the test samples for a multi-cat... |
The DataDictionary and MiningSchema elements for a PMML model requires quite a bit of metadata for each field. With sparse, high dimensional data these could each be many times larger than either the training data or the trained model.
Are there any conventional extensions (or evil non-standard kludges, depending o... |
I have an income distribution dataset which I am attempting to manipulate in Stata (or SAS).
I need to come up with a table listing the number of households earning between one income level and another. The income levels are regularly spaced, say at $10,000 intervals for example.
In other words, for $i=30,000$, I want ... |
I am evaluating and combining a few binary classification models. I am using the ROC and PR curves to evaluate their performance. The problem I am having is that as I try to improve the method, I am improving the AUC-ROC but the PR curve suffers. For example:
As an aside, I am actually adding a weak learner to Method... |
I have a question regarding paired and unpaired tests. I know the difference between both tests. I am using R for Wilcoxon test. My test is a paired test, however the X and Y do not have the same length and R is giving an error. I do not want/think I should use unpaired test.
For example,
I have a subject that makes so... |
Very simply put: Are there any differences in Bayesian and Frequentist approaches to Exploratory Data Analysis?
I know of no inherent biases in EDA methods as a histogram is a histogram, a scatterplot is a scatterplot, etc., nor have I found examples of differences in how EDA is taught or presented (ignoring a particul... |
Mirror thread on Mathoverflow.
(I'm new to Poisson processes, so please edit if my terminology is incorrect.)
This is a special case of a problem I'm working on; hoping for intuition that will generalize to a multi-dimensional Poisson process. The context is approximating a distribution defined by the $\arg\min$ of ... |
Mirror thread on Math.SE
I have a empirical cumulative probability distribution function for a random variable. The random variable is "time to failure" and I have the full curve i.e till the probability reaches 1. I want to know Mean Time To Failure i.e expectation of that random variable. Is there any standard meth... |
Suppose that a certain disease ($D$) has a prevalence of $\dfrac3{1000}$. Also suppose that a certain symptom ($S$) has a prevalence (in the general population = people with that disease$ $D and people without that disease [probably with other disease, but it's not important]) of $\dfrac5{1000}$.
In a previous research... |
My task is to show that Fisher's criterion distribution when the null hypothesis is true follows $F(k-m,N-k)$ when df increases. Here $k-m$ is number of restriction.
So I can write a null hypothesis H0: $b_1=b_2=\ldots b_k=0$.
And I think that I can show that F-statistic follows $F(k-m,N-k)$ using restricted and unres... |
I have a sequence of two possible observations ($A$, $B$) and want to train an HMM with $h$ states, namely $\lambda_h$, to predict the probability of the next observation using the Baum-Welch algorithm. Output probability distributions are Bernoulli with parameter $p_i$ ($i$ is the state number).
My problem is mainly... |
I have performed the path analysis using the sem function in R. The model which I fitted consists of both direct and indirect paths. I have some trouble in interpreting the estimates of the SEM coefficients.
Does R gives the value of total effect = (direct effect + indirect effect) directly or do I have to multiply t... |
When conducting a factor analysis, we need to check the normality and constant variance assumption of the original variables.
If there is HSK existing in the data, can I do different transformations(for example log transformation to x1, squared x2...) to different variables and then conduct the analysis?
Or I should do... |
I've read these SO questions and this is not duplicate of them
https://stackoverflow.com/questions/1306785/best-way-to-statistically-detect-anomalies-in-data
https://stackoverflow.com/questions/3531374/statistical-calculations
https://stackoverflow.com/questions/2221984/algorithms-for-spotting-anomalies-spikes-in-traf... |
I've been looking random forest algorithms for text classification and referencing the Mahout random forest decision tree description. In it, there is a reference to two types of variables, nominal attributes, and real-valued attributes.
However, I'm not particularly sure what a nominal attribute is. Real-valued attr... |
Following on from my earlier posts, as far as I can understand, if I have three correlation coefficients, I will have to test them in pairs to see if there is a significant difference among them.
This means that I would have to use Fishers transformation to work out the z score of r and then the p value of z (which th... |
Im confused about calculating precision and recall for clustering mentioned in this paper, Model-based Overlapping Clustering, A Banerjee et al., (last paragraph of column 1 on page 5).
Suppose, if we are given with resultant cluster indicator matrix $C$ of size $n \times k$ where $n$ is the number of data points and... |
I have a large dataset with patients and I'm studying a rare outcome (~ 2%) and death is a competing risk (mean age ~69 years). I've used the R "cmprsk" package for my statistics and it seems that competing risks and the Cox regression are performing similarly although the competing risk analysis is more conservative g... |
Map/Reduce is great concept for sorting lots of data at once. What to do if you have small parts of data and you need to reduce it all the time?
Simple example - choosing a service for request.
Imagine we have 10 services. Each provides services host with sets of request headers and post/get arguments. Each service dec... |
I have one categorical independent variable with two levels (Group 1 and Group 2). These groups were measured at two times on 10 dependent variables, therefore, I have 2 sets of 10 variables for Time 1 and Time 2. For illustration sake, lets consider Hit_1 (tested at time 1) and Hit_2 (tested at time 2) These 10 variab... |
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