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Please I am about to cluster some data based which have about 15 different columns all of which are numbers(Some categorical while some are measurements) also some of my values are missing in some columns . Please can you give me pointer on how to go about it.
I have previously explored the clustering with weka but I ... |
Based on an answer on Cross Validated I've been looking into implementing a random forest in .NET/C# to classify documents of text.
Looking around the web to see if there are existing implementations, I came across an algorithm for a decision forest on Alglib.
The thing is, I can't seem to find anything specific to "de... |
Here it says that planned comparisons should be linearly independent.
Here (page 13) and elsewhere I see people giving examples of linearly dependent contrasts.
How should this conflicting advice be reconciled?
|
Context:
I ran 3 experiments comparing in each 2 techniques. In each experiment participants had simply to express a preference about which of the 2 techniques they thought was clearest to understand.
30 participants were involved, 10 in each experiment.
No repeated measures were involved.
Now I have a table of the res... |
I have fitted a model using proc reg, say, using this
proc reg data = mydata;
model a = b;
run;
But in this particular application it is better to over-estimate than it is to under-estimate. So I actually want to refit this model this time using the residuals as weights so they an over-estimate is penalised more hea... |
I'm trying the functions to check the cointegration of a matrix.
I'm using Phillips & Ouliaris Cointegration Test
The function in tseries package is po.test and ca.po in urca
The results with urca are:
> ca.po(prices, demean='none')
########################################
# Phillips and Ouliaris Unit Root Test #
#... |
Is it appropriate to do a logistic regression where both the dependent and independent variables are binary? for example the dependent variable is 0 and 1 and the predictors are contrast coded variables -1 and 1 ?
|
I have the graph like this:
R code for generating it is:
DF <- data.frame(date = as.Date(runif(100, 0, 800),origin="2005-01-01"),
outcome = rbinom(100, 1, 0.1))
DF <- DF[order(DF$DateVariable),] #Sort by date
DF$x <- seq(length=nrow(DF)) #Add case numbers (in order, since sorted)
DF$y <- cumsum(DF$ou... |
I have a graph that I did in SPSS
I would like to replicate this in R.
The data file is here: http://dl.dropbox.com/u/22681355/sendergraphR.csv
UPDATE:
I've figured out how to to it for the other graph:
graph2<-read.csv(file="SendergraphR.csv")
ddr <- recast(graph2,no.GREEN+no.RED+Senderidentity~variable,
fun.a... |
If I have the following model y~s*dist(a,b) where s is a constant and dist is a given distribution (assume that the parameters a and b cannot be transformed to account for scaling), how do I model this in JAGS?
I get the following error: "[...] is a logical node and cannot be observed" simply trying the above descripti... |
I'm a student in humanities---maths aren't my strong points, but I'm trying hard, so bear with me please:
I have a survey with seven questions (A to G) and a population divided in four categories (1 to 4). The answer to each question may be True or False.
First, I made a calculation of the total of true answers per per... |
I have the following logistic regression output:
Coefficients:
Estimate Std. Error z value Pr(>|z|)
(Intercept) 0.5716 0.1734 3.297 0.000978 ***
R1 -0.4662 0.2183 -2.136 0.032697 *
R2 -0.5270 0.2590 -2.035 0.041898 *
Is it appropriate to report this in the foll... |
The fUnitRoots package considers lag=2 as the default value in the urzaTest() function (Zivot & Andrews unit root test), while for the ur.za() function in the urca package the default is lag=NULL.
What is the "criteria" to choose a good number of lags?
|
I have the following sorted data (sampling from parametric space [1,5]) with respect to their distances of parameter Theta. i.e.,
Let say N = 1000,
Theta : 1.1, 1.7, 1.9, 2.4, 2.8, . . . , 4.9
Distance : 0.2, 0.3, 0.5, 0.9, 1.1, . . . , 1.9
From literature I know that more than 3% (i.e., 0.03*N) data are not usefu... |
I have got an answer for it from Spacedman. But I am not entirely satisfied with the answer as it does not give me any sort of value (p or z value). So I am re-framing my question and posting it again. No offences to Mr.Spacedman.
I have a dictionary of say 61000 elements and out of this dictionary, I have two sets. Se... |
I am working with sequence data which are long lists of malware win-api calls. I am trying to cast the problem of identifying 'malware behavior' into one of finding sequential patterns. I treat each api call as a single item Itemset. The number of different possible items (api calls) is quite large.
Now, when I apply ... |
I am a social science phd student trying to figure out a statistical test for small conference presentation I am working on. However, I realized I don't know how to run the model I want. Some background on my question:
DV: Change in a person's weight (continuous variable)
IV: Which fruit someone ate for breakfast (cate... |
I am attempting to understand the use (and misuse) of these two response metrics.
When comparing the effect of a treatment to the control:
one approach is to calculate the relative effect of the treatment:
$$E_1 = \frac{X_T - X_C}{X_C}$$
another approach is to calculate the ratio of the treatment response to the c... |
I have the following probit model:
library(foreign)
library(MASS)
data <- read.dta("Braith_statecap_JPR.dta")
data <- data[data$year > 1959,]
model1 <- glm(allons3 ~ confbord + rpc + confbord_rpc + neighlgdp + polity2l + polity2sq + lgdp96l + lnpop + postcoldw + peaceall, data = data, family = "binomial"(link = "prob... |
I want to compare the following percentages:
a<-c(0.59,0.60,0.55,0.55,0.60,0.58,0.67,0.68)
b<-c(0.16,0.21,0.26,0.53,0.84,0.89,0.84,0.94)
the values for a are probabilities calculated with bayes rule
the values for b are number of instances out of the total
I did t.test(a,b)
Is this appropriate? if not how can I comp... |
There are several simple and widely used upper bounds on the tail of the hypergeometric distribution, including $P(X > E[X]+tn) <= e^{-2t^{2}n}$, where X is hypergeometric with parameters N, M, and n. (Thinking of the hypergeometric as describing sampling from a population, N is the population size, M is the number of... |
I measured turbulent velocity in 1Hz sampling rate. To remove fluctuations with T>900 sec I decompose the time series by wavelet packets, problem is that I don't know which levels should be kept and which levels should be removed.
In other words, if the wavelet packet decomposition is imagined as a tree what would be ... |
I've got a dataset of demographic details of store customers and which store they (most frequently) visit. I would like to categorize the stores based on their customers.
To clarify: The issue here is to create clusters of shops, on the basis of the characteristics of the customers who have attended them. In other wo... |
I'm trying to fit a basic measurement error model (from Wansbeek and Meijer pg. 191), using a Bayesian latent variable model. The model appear to converge, but on the wrong answer. I've tried all kinds of variations, and can't get it to work. Why?
Here's the setup: We wish to regress y ~ chi. Unfortunately, instead ... |
Are there any measures of similarity or distance between two symmetric covariance matrices (both having the same dimensions)?
I am thinking here of analogues to KL divergence of two probability distributions or the Euclidean distance between vectors except applied to matrices. I imagine there would be quite a few simil... |
The textbook examples of metaregression I demonstrate how to combine coefficients when the dependent variable has the one distribution (for instance, exclusively binomial or exclusively continuous).
Is there a method of combining regression coefficients for a meta-regression when the dependent variables are a mix of d... |
In R, the eigen() returns descending sorted eigenvalues. However, the eigenvectors do not correspond to these sorted eigenvalues. How do I identify the eigenvector corresponding to the ith sorted eigenvalue?
One approach might be to sort by the norm of the eigenvectors (is there a procedure in R that can do this). I i... |
I'm using ca.jo function in URCA package to use Johansen procedure to check cointegration. I need help to understand the result of that test, this is my example:
> jo <- ca.jo(z, type='eigen', ecdet='none', spec='longrun')
> summary(jo)
######################
# Johansen-Procedure #
######################
Test type... |
I have been going through this article on how to estimate the reliability of a device using Weibull Analysis. The article clearly states that in order to do this, I need to have information in the following form:
# Age_A Age_B
1 26 16
2 31 24
3 35 30
4 38 36
5 41 42
6 44 ... |
Possible Duplicate:
R language and statistics hypergeometric test
This is in reference to my first question, although I have got an answer for it from Spacedman. But I am not entirely satisfied with the answer as it does not give me any sort of value (p or z value). So I am re-framing my question and posting it agai... |
I was exploring Weibull analysis for understanding reliability of two specific specimen. I used the R package, "weibulltoolkit" and "survival" to get the plot in question. The dataset is big so I am not posting it.
X = read.table("./test", header=T)
d <- data.frame(ob=X, state=1)
s = Surv(d$ob, d$state)
plot.wb(s)
Fr... |
I am trying to compute inter-rater reliability for ranking multiple objects across multiple scenarios.
For example suppose for scenario A we had multiple objects and multiple raters like in the table below.
Object V W X Y Z
Rater1 2 1 3 4 5
Rater2 1 3 5 2 4
Rater3 4 5 2 1 3
I... |
I have a dataset of genomic information which I'm going to be comparing with various biochemical markers. Unfortunately a lot of the biochemical markers have limited ranges in their assays, so I have a lot of data that looks like "40", ">45", "35", ">45" for tests that have a threshold at 45 (for example).
My intended ... |
I have some experience with both FLD and LR for classification.
On most data sets, I get very similar results, which raises the question - are FLD and LR related in some why?
An idea, for example, if I assume a normal distribution on the likelihood function instead a of a logistic function, does the maximization come... |
First of all, my apologies if I mess up the terminology. I've been out of math for several years, so I'm certain I'm going to use terms incorrectly. Also, though I concentrated mathematics in college, I have lost those legs; I'm particularly braindead when it comes to remembering what means what with mathematical notat... |
I run into a problem where I would like to build a GEE in R with cubic regression splines (or any other spline type) for a longitudinal data set and an urgent need for grouping and multiple autocorrelation structures. However, I did not find any package capable allowing for that.
If anyone could give a suggestion for ... |
I'm trying to simulate a data protocol running over a 5 Mbps RF link. The datasheet for the RF chip gives a logarithmic BER vs SNR plot (BER := bit error rate; SNR := signal to noise ratio), but to simplify I am choosing to fix the BER to the same value that many of the RF characteristics are measured: BER = 10^-4.
Ho... |
I have some real data from the past. The data show application demand (for example cpu demand) at a certain time slot. The data looks like this for example:
3,2,1,5,7,8,9,1,3,12,4,5
These 12 values show the application demand of cpu in first 12 hours of a day respectively: 3 was the demand between 00:00 and 01:00m, ... |
I have a dataset:
Response: categorical, 9 levels.
23 predictors: binary, with many 0's.
Number of samples: 64.
I'm interested to know the dependence of (each level of) the response on predictors.
Grateful for any suggestion to start.
Edit: The topic is related to the analysis of the scientific definitions regarding... |
I have calculated a posterior
$p(P_1, P_2 | D)$
where $P_1$ has a few and $P_2$ has many dimensions. In the process of calculating the maximum a posteriori estimate for $(P_1,P_2)$ given certain data $D$, I calculate the maximum projection along all dimensions of $P_2$, i.e.
$f(P_1,D) = \underset{P_2}{max} [p(P_1, P_2... |
This is more of a historical related question. Edmond Halley in 1693 published an actuarial table showing mortality rates. The tables show yearly statistics for ages 1-84 and a summary statistic for ages 84-100. I have searched hard for the missing data, but with no luck (See also Geoffrey Heywood's article).
So this ... |
Say $k \sim Bin(N, p)$. What is the distribution of $N$, given fixed $p$ and $k$? Looks like Poisson but starting at k instead of zero (???)
Thanks.
EDIT: Application: I have some real number of birds ($N$), each is seen with probability $p$. I see $k$ birds and want to estimate the real number of birds ($N$).
|
It is often argued that the bayesian framework has a big advantage in interpretation (over frequentist), because it computes the probability of a parameter given the data - $p(\theta|x)$ instead of $p(x|\theta)$ as in the frequentist framework. So far so good.
But, the whole equation it is based on:
$p(\theta|x) = {p(x... |
I was looking for the proof of convergence for perceptron algorithm with margin. I was not able to find it in any pattern classification text book or over the internet.
Can anyone here please point to a text or reference for the above?
|
I've read papers comparing them, but never seen a study that used them
together. Is this done? Why or why not? Suppose you use
ANCOVA to analyze a reduced sample of matched pairs generated using
propensity scores (assuming the propensity scores are estimated from
the complete set of confounders X that jointly effect t... |
I'm trying to estimate what effect the tariff rate in a specific country has on evasion of tariffs (or rather the underreporting of the value of goods in customs). My dependent variable is a proxy for evasion and the explanatory one is tariffs. I have data spanning continuously over about 15 years.
Now I want to contr... |
I am using a BYM model in WinBugs to describe the distribution of a non-infectious disease.
The model at present is a standard enough BYM model without much modification, (a Poisson-gamma hierarchical model with terms for structured and unstructured residuals) as follows:
model
{
for(i in 1:N)
{
observed[i] ~ dpo... |
attached is a (German...) bar chart which shows the five possible values of the one variable "Culture": Nix, BV, Candida, Mix, Unspecific.
The variable is measured at three different times, 1 (blue), 2 (green), 3 (something).
I am looking for some kind of test to determine that the number of measured individual values ... |
I am fitting an ARIMA model on a daily time series.
Data are collected daily from 02-01-2010 to 30-07-2011 and are about newspaper sales.
Since a weekly pattern in sales can be found (the daily average amount of copies sold is usually the same from Monday to Friday, then increases on Saturday and Sunday), I am trying t... |
At the moment I'm trying to interpret the green and red dashed lines in a contour plot when visualizing a generalized additive model (GAM) with R. These two lines seem to be something like confidence bands, but I'm not sure how to interpret these dashed lines in a contour plot.
Does anybody have experiences with conto... |
I'm using sctest function in strucchange package to check if there are breaks in my series.
I would like to understand how to interpret its result, in an example i get:
> g <- sctest(cars$dist~cars$speed+0)
> g
Recursive CUSUM test
data: cars$dist ~ cars$speed + 0
S = 0.9147, p-value = 0.06379
What does it mea... |
This question is motivated by this one. I looked up two sources and this is what I found.
A. van der Vaart, Assymptotic Statistics:
It is rarely possible to compute a profile likelihood explicitly, but
its numerical evaluation is often feasible. Then the profile
likelihood may serve to reduce the dimension of the... |
I have a data table where I need to calculate the number of days each user performs an action.
The structure is like this.
UserID Date TimesActionDone
A 20110601 3
A 20110605 0
A 20110609 10
B 20110701 0
B 20110710 0
B 2... |
I am looking for an online Chi square calculator. I can see there are many for 2x2 tables. I am looking for an online calculator which can accommodate dimensions beyond 2x2.
|
Can you suggest me an algorithm and probably a real code for multiple output learning, where input of the model is vector of around 10 000 values and output is, for each input vector, an output vector of 1500 dimensions (so, it's kind of a big dataset)?
In my opinion neural network can handle this number of values, but... |
I have two variables:
a: 12,13,15,10,9,8
b: 15,15,15,15,15,15
variable 'a' is aggregate numbers of choosing a particular answer (0 or 1) for each case (6 cases in this example).
So for example for the 1st case 12 out of 15 participants chose 1, 13 out of 15 in the second case, 15 out of 15 in the third etc.
variable ... |
I have two lists of price (stock) and I need a method to detect if there are structural breaks inside those series. What method can I use?
For each serie I have around 600 prices (daily).
Thank you in advance
|
I have been trying to understand the function anovan in MATLAB to perform n-way ANOVA to test the effects of multiple factors on my data. What caught my eyes when I read the help page for this function is that, in their example, the p-value for factor X1 changes from being insignificant (p>0.05) to being significant (p... |
A random forest is a collection of decision trees formed by randomly selecting only certain features to build each tree with (and sometimes bagging the training data). Apparently they learn and generalize well. Has anybody done MCMC sampling of the decision tree space or compared them to random forests? I know it might... |
Suppose I have samplings from two distinct populations. If I measure how long it takes each member to do a task, I can easily estimate the mean and variance of each population.
If I now hypothesise a random pairing with one individual from each population, can I estimate the probability that the first is faster than t... |
I am running lots of simulations in JAGS 3.1.0 , which I have compiled from source. I am using a mid-2009 Macbook Pro 13 2.53GHz.
Is there any step by step tutorial (from scratch) to compile ATLAS or GotoBLAS for JAGS and R (where I use the rjags package)? There are information on ATLAS, GotoBLAS, JAGS, and R compilati... |
I have a data set of 11,000+ distinct items, each of which was classified on a nominal scale by at least 3 different raters on Amazon's Mechanical Turk.
88 different raters provided judgments for the task, and no one rater completed more about 800 judgments. Most provided significantly fewer than that.
My question is ... |
I have run two separate logistic regressions and would like to assess which model fits the data better. Each model has 1 predictor.
Here's the output for both:
Model 1:
Deviance Residuals:
Min 1Q Median 3Q Max
-1.280 -1.046 -1.046 1.078 1.315
Coefficients:
Estimate Std. Error z v... |
I have data on two processes, where the process assigns elements into ordered bins. I am interested in testing for agreement between the processes. What is the best way to do this (R code)? Here is the dummy data with counts for the 2 processes and 4 categories). I am not familiar with weighted kappa (which I have seen... |
Starting from an "a priori" set of models based on my knowledge about potential relations between my dependent variable and the independent variables considered, I use AIC to find best models. More specifically I calculate Akaike weights then Evidence Ratio (ER) and consider that models with a ER < 2 are equally likely... |
I've got a supervised learning problem where I've got about 15 features, mostly numeric, and I'm mapping these to a set of 5-7classes. Using decision trees or forests, I'm able to get confusion matrices that I'm quite satisfied with, but I'm interested in seeing what the "top" rules RIPPER would find would be.
I've bee... |
I am running a linear regression on daily price returns and I want to capture the interaction between subsequent returns:
$r_{t+1} = \alpha + \beta_1 r_t + \beta_2 r_{t-1} + \beta_3 r_t \cdot r_{t-1} + \epsilon$
Where $r$ is a geometric return ($p / p_{t-1}$).
Each coefficient is interperable as a linear multiplicati... |
In $\chi^2$ testing, what's the basis for using the square root of the expected counts as the standard deviations (i.e. the expected counts as the variances) of each of the normal distributions? The only thing I could find discussing this at all is http://www.physics.csbsju.edu/stats/chi-square.html, and it just mentio... |
I have a data set of x,y,z data and I'd like to do a bicubic interpolation. x and y are spatial coordinates and z is a temperature.
Below there are two images. The first one is a (gnuplot) plot of my dataset and the second one is an interpolated version (set pm3d interpolate 10,10).
Now I'd like to do this interpolatio... |
I was recently told that it is not allowed to include static covariates in mixed effect models. I can believe that this could be true, however, when I have time series data, and season is a grouping factor, then the differences between the static covariates in the different seasons should be tested, or not?
If it is n... |
I am working with the data obtained from a travel survey from a town. I have the data from mean of trips made by different travel modes on the day of the survey. From a national suevey I have got data of total number of trips made by each travel mode for the towns with similar populations.
Could you suggest a way to ... |
I have run 3 separate logistic regressions and would somehow like to summarize how well the model fits the data graphically.
Any suggestions?
|
A discrete distribution with mass function
$$p(x;k) = \frac{k}{(x+k)(x+k-1)},\quad x = 1,2,\ldots$$
arises on page 9 of this paper.
For $k=1$ it is a Yule-Simon distribution with $\rho=1$, but I haven't found any other examples.
Does it have a name? Does it appear in any other contexts? Is there a simple stochastic pro... |
I'm combining two surveys in a case-control design. Survey B is drawn from the "case" population, and includes all the variables I need for analysis, plus some extras. Survey A samples a general "control" population, and includes most (not all) of the variables I need, plus some extras. For notation, let's say we ne... |
I have a dataset with two variables, one is the optimal response and the other is the proportion choosing that response (number of times chosen).
I would somehow like to compare the two an visually present how close they are.
Is it appropriate to use linear regression?
Here's the data:
optimal <- structure(list(Probabi... |
How can I calculate the stock volatility in percentage?
Do i have to use sd() function without any other calculation ?
Thanks
|
Possible Duplicate:
Poisson regression vs. log-count least-squares regression?
This post got me to thinking about when it makes sense to use poisson regression instead of log transforming a continuous non-negative outcome variable. I wondered if and when it might make more sense to log transform in some cases. (Th... |
As I am only familiar with the basics regarding decision trees I would like to ask, with the risk of stating silly question: Is it possible to perform recursive partitioning with the group median as the response/objective?
For example, in stead of R's rpart() using means, could a similar tree be created with medians?
... |
I have two variables both are binary.
I would like to see how well one predicts the other.
Is it possible to do this in logistic regression? variables are coded as 0 and 1 but 1 does not indicate that something is 'correct'. can I still use logistic regression to see how well it is predicted?
|
I have a customer data set with the following data:
The number of purchases that each customer made
The Date that they made each purchase
The Date that they signed up
The amount they spent on each purchase
I want to segment my users into three groups:
Great Customers
Ok Customers
Bad Customers
Is there a tool... |
Setup
I found a paper on that has a varient on normal auto-encoders (contractive) which for its gradient uses the following regularization penalty:
$$\left|\left|J_f(x)\right|\right|^2_F = \sum_{ij}{\left( \frac{\partial h_j(x)}{\partial x_i} \right)}^2$$
where $\left|\left|\cdot\right|\right|_F^2$ is the Frobenius no... |
Which is more correct?
"Accept the null hypothesis"; or
"Do not reject the null hypothesis"
Is there truly a separate meaning that I'm missing here?
|
I have a three types of experiments with many measurements taken. I want to show that using clustering on the unlabelled measurements, I can uncover the three groups. Now using kmeans plus, I get around 60% accuracy. Which if it was binary, would be poor, but how do I quantify how good that is for three categories? Is ... |
I am trying to learn how to fit a probability distribution to a vector of data, using the program R, but there are a lot of potential probability distributions to use! So my question is, how do I find the best distribution for my data, and how do I prove that I have picked the right distribution? Can I acquire AIC va... |
Can anyone explain me in simple english why does mean and median play a important role on Data mining. Actually finding a mean and median is of what use?
And many people say's median is better at times than mean, why so? And I'm a novice in data mining so it will be really good if the answer is in simple terms.
|
Please, take a look at the chart below.
As you can see the first period the volatility is high and the second is low.
How can I check if the volatility is stationary (homogeneous) during the entire period?
The plot represents the residuals of a simple linear regression.
|
Given a model $a_{n}\cdot x^{n}+ a_{n-1}\cdot x^{n-1}+...+ a_0 = y + e$, where $e$ is some unknown (but assumed normally distributed) error and $x$ and $y$ are observations.
Now, how would one to estimate the confidence intervals of the coefficients $a_.$?
AFAIU, a simple procedure based on the covariance $(X'X)^{-... |
Does anybody know how to arrange a cross validation so I can compare two models (negative binomial with quasi-Poisson)? I know some theory beyond cross validation, but don't know what kind of cross validation makes sense (leave one out, simple cross validation, k-fold) when comparing two glms with about 1000 observatio... |
I am looking at using the lasso as a method for selecting features and fitting a predictive model with a binary target. Below is some code I was playing with to try out the method with regularized logistic regression.
My question is I get a group of "significant" variables but am I able to rank order these to estimate... |
I have a categorical independent variable (two levels: condition 1; condition 2) and ordinal(?) dependent variables (numerical magnitude shifts (e.g. -3 if there was a decrease in number magnitude from 4 to 1). I now want to assess whether the condition predicts a change in the dependent variable. It is a repeated meas... |
I am looking to do classification on my text data. I have 300 classes, 200 training documents per class (so 60000 documents in total) and this is likely to result in very high dimensional data (we may be looking in excess of 1million dimensions).
I would like to perform the following steps in the pipeline (just to give... |
I'm testing the residuals of a linear regression using Breusch-Pagan Test to detect Heteroscedasticity.
This is the plot of the residuals:
and this is the R code:
> library(lmtest)
>
> mod <- lm(rnorm(1000)~1)
>
> bptest(mod)
studentized Breusch-Pagan test
data: mod
BP = 0, df = 0, p-value < 2.2e-16
Could s... |
I have a hidden binary random variable Z that can have a value of either 1 or 0. There is some true probability P(Z=1) = z that I do not know.
I also have two separate pieces of "evidence" that give some information about the state of Z:
P(Z=1) = x
P(Z=1) = y
I'm interested in estimating z by combining the evidence ... |
I have a few doubts in understanding SVMs intuitively. Assume we have trained a SVM model for classification using some standard tool like SVMLight or LibSVM.
When we use this model for prediction on test data, the model generates a file having "alpha" values for each test point. If alpha value is positive the test p... |
I am reading Ruppert's Statistics and Data Analysis for Financial Engineering, which contains the following theorem:
Let $Y_1$, $...$ , $Y_n$ be an i.i.d. sample with a CDF $F$. Suppose
that $F\;$ has a density $f\;$ that is continuous and positive at
$F^{-1}(q)$, 0 < $q$ < 1. Then for large $n\;$, the $q^{th}$ sa... |
I have computed correlation coefficients for 90 day increments of a time series (i.e., one coefficient for days 0-90, 91-180, etc.). It was computationally very expensive to compute these and I would like to analyze correlations over 6 month periods, 1 year periods etc. Is it possible to some how to combine these coeff... |
I read in a pattern classification text, that if we consider weight vectors whose components are integer valued, the perceptron procedure would terminate in a finite number of steps.
What is the intuition and theory behind this?
EDIT: It is a homework problem from the text book Pattern classification by Duda, Hart, Sto... |
I'm trying to run the libsvm-provided wrapper script easy.py on a training set of 100K rows, each row has ~300 features. The feature data is relatively sparse, say only 1/10th are non-zero values.
The script is excruciatingly slow, I'm talking days (or more). I ran the same script on 1% of the data, and it finished in ... |
I'm using smooth.spline for some basic smoothing splines. However, I need to switch to a function that allows me to use multiple independent variables. I'm having trouble finding one, other than mars, which is giving me bizarre results so I think it may not be what I'm looking for. My stat background is very limited... |
I need to draw two time-series plots on a graph in R. The problem I am facing is as follows. Each plot has 200 data points, and therefore, the graph that I have produced looks clumsy on my two-column pdf file. I am trying to use different pch values, but still the graph doesn't look good to me. Could someone help me to... |
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