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I would like to classify a relatively large set (over 9000) of short times series. The length of each sequence varies, but I would say about 80 % has between 2 and 9 observations. While I could use a simple trendline (maybe combined with a variance measure) to describe each these sequences, I would like to go a step be... |
I have a temporally ordered discrete valued data. The only possible states for the data are:
{1,2,3,4,5,6}. So the series is something like {1,2,3,5,6,4,3,5,2,......} I want to forecast the next value of the series based on past data.What are the methods appropriate for this?
Now please note that my question is not rep... |
I am currently doing a project which involves pothole detection and neural networks. So far, I have an Android phone that reads Accelerometer readings and writes the X,Y,Z Axis aswell as the Amplitude and current timestamp into a CSV file. The data is then normalized using min-max normalization and uses the Y axis read... |
How is it possible to identify quickly (without doing many tests) an approximative number of clusters from a dataset which is not vary large, even if this value is not the correct number of clusters, I just want to identify a reasonable value representing the number of clusters from this small dataset.
Note1: that I do... |
I'm having a little trouble early on using the convert() function in RTAQ to convert .csv taq intraday trade data into an .RData format. I type this:
> from <- "2012-02-01"
> to <- "2012-02-29"
> ###convert data to .RData format
> convert(from, to, datasource = "/home/taylor/Desktop/trading",
datadestination = "/home... |
I have logs from an autocomplete form, which I would like to leverage to increase the intelligence of the results it returns.
I have a project that revolves around users selecting opera characters from a database of ~15,000 unique characters. My difficulty is that each character appears in the database as only one name... |
Suppose I have a data set, and have trained up a regression model (happens to be a bayesian linear model, I'm just using the R package). The model outputs a wide range of values, greater than 0 and less than 0, although the actual output can only be greater than 0.
Is there an accepted away to apply bounds to the outpu... |
I am taking a theoretical approach to my multiple regression but the R squared and Adjusted R squared are both really low. I assume this means I can't improve my values with existing data and that the model is invalid? Can I do anything about it?
I am trying to test the causes of the intensity of organised violence (DV... |
I intend to use a hierarchical binomial model which would look like the following in BUGS language :
model{
for(i in 1:I){
y[i] ~ dbin(theta[k[i]],n[k[i]])
}
for(j in 1:J){
theta[j] ~ dprior(alpha, beta)
}
alpha ~ dhyperprior.alpha
beta ~ dhyperprior.beta
}
I wonder about the choice of the prior on $\theta$ and ... |
I wonder whether it is possible to perform within R a clustering of data having mixed data variables. In other words I have a data set containing both numerical and categorical variables within and I'm finding the best way to cluster them. In SPSS I would use two - step cluster. I wonder whether in R can I find a simil... |
I need to analyze some data obtained from "in vivo" software testing. Unfortunately I’m a SW engineer, not a statistician.
The dataset contains observations for a number of messages sent between 2 nodes (actually, sent and returned).
There are two independent possible outcomes: 1. “message was flagged” and 2. “messag... |
I started my PhD study in Econometrics last month. Currently I am studying some compulsory course works (Probability theory and Statistical Inference), and also reviewing the literature in my field. I would also like to study some more mathematics, which I believe will make me more prepared for my formal research. Can ... |
What is the probability distribution function of the variable $y$ given by
$$y=\frac{x_1}{x_1-x_2},\quad \: x_i\ge 0,$$
given that $x_1$ and $x_2$ are independent and identically distributed and
$$x_i = c+z_i,\quad i=1,2 $$
where $c$ is a real nonnegative constant and $z_i\sim\chi^2_\nu$.
|
Suppose we have a Cox-PH model and death is the outcome of interest. Suppose we have the predictors $X_1, X_2$ and $X_3$. Then does the PH assumption mean that for any person (i.e. arbitrary values of $X_1,X_2$ and $X_3$) the hazard of death is $c \cdot h_{0}(t)$ where $c$ is a constant? So the hazard function is the s... |
Testing for cointegration tests to see if the residuals from a regression between the two variables is a stationary process. So wouldn't a test on those residuals for heteroskedasticity be the same thing? To detect if the variance of the errors is stable and the error terms are not a random walk? Wouldn't a White test ... |
I'm using a negative binomial GLM to predict individual level scores on a psychometric test that ranges from 0-27 and presenting the coefficient "incidence rate ratios".
It seems a little strange to use the term "incidence rate ratio" when actually it is a psychometric score ratio. Should I still use the term "incidenc... |
Here is the article in NY times called "Apple confronts the law of large numbers". It tries to explain Apple share price rise using law of large numbers. What statistical (or mathematical) errors does this article make?
|
I have a 2D-histogram for two vectors, s1 and s2, generated using the hist3 function in Matlab:
[hist2D, binC] = hist3([s1' s2']);
I am normalizing it by making its total volume equal to unity, in the following manner:
L = binC{1}(2) - binC{1}(1);
B = binC{2}(2) - binC{2}(1);
totalVolume = sum(sum(hist2D.*L*B));
prob2... |
In my previous question I needed to help with ellipse region extraction and determine if point lies in that region or not.
I ended up with this code:
library(ellipse)
library(mvtnorm)
require(spatstat)
netflow <- read.csv(file="data.csv",head=FALSE,sep=" ")
#add headers
names(netflow)<-c('timestamps','flows','flows_tc... |
I am running a simple code comparing insect abundance on a vegetated and unvegetated surfaces. Design is RCBD. 1 factor with 2 level (vegetated and unvegetated). 10 blocks. Distribution of residuals is non normal and variance of the two populations are unequal. I could log transform but wanted to explore using GLIMMI... |
Possible Duplicate:
Regression on a non-normal dependent variable
If the dependent variable in a multiple regression is not normally distributed, what can be done to correct it?
|
I have a prototype machine producing parts.
In a first test the machine produces $N_1$ parts and a binary classifier tells me that $d_1$ parts are defective ($d_1 < N_1$, usually $d_1/N_1<0.01$ and $N_1\approx10^4$) and $N_1-d_1$ parts are good.
Then a technician makes some changes in the machine in order to decrease t... |
I am reading a bit about Bayesian analysis, but I cannot understand the difference between the classic quantile-based intervals and the Highest Posterior Density Intervals. What is the difference between the two? I have simulated and plotted some data, the Q95% and the 95% HPDI seem to be similar but not identical. Are... |
What range of sample size would increase the likelihood of finding significance in a 2x2 chi square? I did not find significant relations between artists (n=36) and non artists (n=20) on 2 levels of mood (mild or severe disorder) with more than 5 in each cell.
|
I am currently arguing with someoe on how to correctly treat data with multiple measurements for each subject. In this case data was gathered for each subject within a short time for different conditions within each subject. All measurements gather exactely the same variable, just multiple.
One option now is to just gr... |
Is there a function in R to calculate the generalized determinant of a singular matrix? (similar to the ginv() used to compute the generalized inverse)
|
If the Martingale Residuals indicate that a predictor $X$ violates the proportional hazards assumption but the Schoenfeld Residuals indicate that it does not....which one should you trust?
|
At https://github.com/OpenMDAO/OpenMDAO-Framework/issues/599 it is stated that non-square Latin Hypercube experimental design is not well defined (I assume that for higher dimensions that means hypercube must have the same length in every dimension).
I'm wondering why that is. Would it not be possible to, for example,... |
I want to create a climate model ensemble, testing 5 parameters (real, uniformly distributed between two values), using a latin hypercube approach. The problem is that I'm not sure how many replications I want to do. Is it viable to do one latin hypercube of 20 samples, and then another of 10? How would I make sure the... |
Is there a good way to measure smoothness of a time series in R? For example,
-1, -0.8, -0.6, -0.4, -0.2, 0, 0.2, 0.4, 0.6, 0.8, 1.0
is much smoother than
-1, 0.8, -0.6, 0.4, -0.2, 0, 0.2, -0.4, 0.6, -0.8, 1.0
although they have same mean and standard deviation. It would be cool if there is a function to give me a sm... |
Despite the title, this is a more general and clearly solvable problem, I just can't research it because I have no idea what it's called.
Assume you are trying to buy something (such as a house) where there are many choices and gathering information about each choice is expensive enough to care about. Furthermore, ass... |
What method is used to calculate confidence intervals in R's MASS package function confint.glm?
The helpfile states that:
These confint methods call the appropriate profile method, then find
the confidence intervals by interpolation in the profile traces.
Can anyone point me in the direction of some literature that... |
I try to estimate survival curves based on a Kaplan-Meier estimator using proc lifetest. However, SAS outputs an error message which I do not manage to circumvent. Can you help me? The data set is available here.
My code
filename work_di "TO BE COMPLETED";
data data;
infile work_di("data.txt") dlm="09"x firstobs=2... |
I'm running an ANOVA model. I found my model does not meet constant variance assumption and corrected for that using a weighted ANOVA model. I don't think that changes anything..
After I run the weighted ANOVA model in SAS, I find one of my fixed effects is not significant with p-value = 0.3, but when I run LSMEANS on ... |
I have learned that resampling e.g. bootstrapping could give us better results for some problems. If we have a huge data set (millions of values) does it make sense to do some kind of resampling or these methods are only suitable when the data set is not that big?
|
I have recently been made aware of the Lasso algorithm and found that the package
glmnet can be used to solve it. (I have the glmnet package on R).
If I have a matrix $A$ and a vector $y$ how do I solve the lasso problem of
minimizing $\|y-Ax\| + \lambda \|x\|_1$? Also, how do I solve the constrained problem: minimize ... |
I am probably breaking multiple rules by posting this question here, but I really want to find the answer to this question and after looking for several hours, I don't seem be getting anywhere. I already posted the question on StackOverflow and I didn't get any response (my guess is that 90% of R users are here and 80%... |
So I'm looking into methods in selecting the best number of hidden states for a hidden markov model, given I don't know what how many states "generated" my data. One method I've seen a lot is to learn lots of models with different numbers of states and then perform BIC on them. Another method is too place a dirichlet p... |
I open a .sav file in PSPP (an open-source alternativ to SPSS) with
get file=...sav
Now I would like to see how many rows there exist.
|
How to test the statistical significance of the difference of two univariate Linear Regression betas?
Hi all,
There are two samples of data: D1 and D2.
On data D1 we do a univariate Linear Regression and get the coefficient beta1.
On data D2 we do a univariate Linear Regression and get the coefficient beta2.
How do I t... |
Possible Duplicate:
How to do a pretty scatter plot in R?
How to use ggplot to do the binned quantile plots(one type of scatter plot)?
Hi all,
I have done scatter plot: plot(x, y).
Now I wanted to do binned quantile plots... can ggplot2 help me?
For example, we bin x data into 10 bins.
For each bin, we draw the 10 d... |
@vucko gave me excellent answer on my question, unfortunately using Mathematica code. I'm trying to rewrite it in R and I'm lost in R functions providing kernel density estimation.
I have bivariate dataset with more than 46,000 rows (so I am also looking for a high performance solution--@vucko's solution is very time c... |
I browsed through lots of literature on Linear Discriminant Analysis on the web. I can say that, I have understood most of it.
This is what I understood. You take the data, calculate mean of the data, mean per class, scatter between classes, scatter within a class. Use this information to project multi-dimensional data... |
Assume I've built a recommender system that (given say movie rankings or whatever of many users) will produce a list of 10 recommended movies for each user to watch.
Imagine that I also have some large pool of movie items, together with a log of user ratings together with movies that they actually decided to watch. So ... |
If I want to nonparametrically bootstrap the following matrix (with replacement):
1 2 15 12 14 22
3 5 1 9 29 19
2 22 12 11 9 13
14 3 6 16 17 23
5 34 22 12 13 16
7 14 13 19 17 3
Would I "jumble" up only the rows, to obtain matrices like:
5 34 22 12 13 16
14 3 6 16 ... |
For those of us that work in data mining building predictive models what is the benefit of a Bayesian belief net? I am sure I am just naive as I have not studied them in depth, but what are the advantages?
It seems to me that on the surface, from a prediction stand point, there are typically better classifiers availab... |
Years ago I read that there's a certain trick researches resort to when they want to obtain survey data regarding questions where one wouldn't expect people to answer honestly, such as "Do you beat your children?".
The trick had something to do with randomization and mixing the contentious questions with innocent ques... |
I have a set of some 50,000 data points. There is one dependent variable which is categorical in nature and there are some 100 possible explanatory variables. Out of these 100, I have to select some 10 variables which are most significant in terms of determination/explanation of dependent variable. Can you please sugge... |
I need to forecast the following 4 variables for the 29th unit of time. I have roughly 2 years worth of historical data, where 1 and 14 and 27 are all the same period (or time of year). In the end, I am doing a Oaxaca-Blinder style decomposition on $W$, $wd$, $wc$, and $p$.
time W wd wc ... |
This question is a follow up to the question I asked yesterday.
Here is the current situation again. I have data for a within subject measurement, where each variable is measured repeatedly. The repetitions are used to cancel out random fluctuation of the measured variable. Each subject was exposed to each of the cond... |
I am working with some data that has been classified by domain experts. However, the classification they use is not 100% accurate. How can I deal with data that may not be correctly classified?
Are there any models which are more resilient to data that are not classified with 100% accuracy? Does such a classification b... |
Given an ARMA model and a historical time series, I'm trying to create a set of $n$ forecast scenarios, where each scenario $s$ is a potential future hourly time series $x_s[t]$, with a given probability, $p_s$. I'm familiar with how to generate an ARMA point forecast for a given horizon - how do you extend this theory... |
I'm having an argument with a colleague (neither of us have a strong statistical / research methods background) on whether we should randomize questionnaire layout.
The survey in question is a feedback forms on teacher performance which are distributed for high school pupils. So one pupil gets up to 20 surveys (on each... |
Damgaard and Weiner in Describing Inequality in Plant Size or Fecundity discuss computing the Lorenz asymmetry coefficient, S as well as confidence intervals for the estimates of S for a sample.
D A Seekell, P D'Odorico and M L Pace in Virtual water transfers unlikely to redress inequality in global water use also dis... |
I know that the beta weight tells you the relative importance of a predictor (IV) in predicting the criterion (DV).
However, is it true that beta weights can not be compared across different samples? (i.e. if I run two different regressions, both with the same independent variables, but different dependent variables, ... |
I'm doing a lot of work on the Wikipedia page for this distribution:
http://en.wikipedia.org/wiki/Dirichlet_compound_multinomial_distribution
The actual name of the page is "Multivariate Pólya distribution". However, in the text I've been writing, I actually use "Dirichlet compound multinomial distribution", abbreviat... |
While studying for my stats course, I was trying to understand the difference between one-tailed and two-tailed hypothesis tests. Specifically, why does the one-tailed test reject the null while the two-tailed one does not?
An example:
|
I want to compare data that proportions among three different groups e.g.:
ID Group Prop.Nitrogen
1 A 0.89
2 A 0.85
3 B 0.92
4 B 0.97
Following Wharton and Hui (doi:10.1890/10-0340.11)
I though I'd see if these data would be better dealt with using a logit transformed.
When I look a... |
In "R - project" I am trying to estimate the panel data lm model with plm function. When I include 3 dummy variables into the regression it doesn't appear in the summary of the model, but when I estimate a simple lm model it appears.
Why is it so? What should I do to estimate the statistics for those dummy variables?
|
(To see why I wrote this, check the comments below my answer to this question.)
Type III errors and statistical decision theory
Giving the right answer to the wrong question is sometimes called a Type III error. Statistical decision theory is a formalization of decision-making under uncertainty; it provides a conceptua... |
The univariate exponential Hawkes process is a self-exciting point process with an event arrival rate of:
$ \lambda(t) = \mu + \sum\limits_{t_i<t}{\alpha e^{-\beta(t-t_i)}}$
where $ t_1,..t_n $ are the event arrival times.
The log likelihood function is
$ - t_n \mu + \frac{\alpha}{\beta} \sum{( e^{-\beta(t_n-t_i)}-1... |
I have built and refined a regression model using the ordinal package in R. The measure is $0>1>2>3>4>5$ (Yes/No questions) and is repeated every 10 minutes for an hour (episode) within the same person, twice a week for up to 6 weeks, but average 3 weeks. I have 6000 such observations on 1000 hours for 150 people.
When... |
My research is a about clustering a huge data set. Right now I'm not using any technique for feature selection, because I only need 3 attributes from each row. I hope I'm making myself clear, lets say I have 1000 rows of data and in each row there are at least 15 attributes (field with different category, e.g. IP add, ... |
Imagine I have a network, and in this network I have $n$ nodes of interest.
I calculated the average shortest path (asp) between these nodes.
I want to see if they are statistically significantly close to each other.
Therefore I select $n$ nodes from the network randomly, and work out the average shortest path length. ... |
I would like to find the answer to the following question. A casino offers games with one of the following 21 p’s [0; 0.05; 0.10 .... 0.90; 0.95; 1] and one of the following 21 v’s (values) [0; 5; 10 ... 90, 95, 100]. The person taking part in the game either wins the v or he gets nothing.
In sequence A, 98 games are ... |
While studying ANOVA analysis, I meet an example related to the ANOVA table given in the attached figure
Here,
$Y$ stands for change in hemoglobin (%)
$X_1$ stands for duration of the operation (min)
$X_2$ stands for blood loss (ml)
Based on this ANOVA table, several arguments are made:
$X_2$ has a significant line... |
I have the following hypothesis:
$h_0 : \frac {\sum {a_{i}}} {\sum {b_{i}}} = x \\
h_1 : \frac {\sum {a_{i}}} {\sum {b_{i}}} \neq x$
Where $a_i \propto X b_i$ and $X$ is a random variable.
How would I test this hypothesis?
Edit: Switched a and b around in the 3rd equation
|
I am using spotfire (S++) for statistical analysis in my project and I have to run multinomial logistic regression for a large data set. I know best algorithm would have been mlogit, but unfortunately that is not available in s++. However, I have an option of using glm algorithm for this regression. I want to clarify t... |
I have some regression equations, take from various published studies, that predict an individual's mass from its length. Typically only an equation's parameter values, R-squared, standard error of the estimate, and sample size are reported in a manuscript. I'm then using those equations to predict the masses of indivi... |
I'm working on a large database. I want to explore whether certain batch jobs run in more or less time after a change was than they did before the change.
There are about 90 distinct batch jobs. They run according to different timetables, so some of them are called only once a week, and some are called hundred of times... |
I am using the glmfit function in MATLAB. The function only returns the deviance and not the log likelihood. I understand that the deviance is basically twice the difference between the log likelihoods of the models but what I don't get is I am only using glmfit to create one model, but somehow I am getting a deviance.... |
I'm conducting a meta-analysis on two genome wide association studies (GWAS), each consisting of 150 SNPs, for which I computed summary statistics for association.
I'm using the R package meta and the function metagen.
It seems to me that this function is able to combine studies but on single measurement effect (I have... |
I'm running a negative binomial regression to test the intensity of violent events in a given location. One of my X variables has a negative beta coefficient (BC), however the hypothesis behind that variable is a 'negative decline in X contributes to a positive chabe in voilence'. My X variable is vegetation cover - s... |
Let's say we have a RxC contingency table, with R=C. How could one best repopulate the table such that:
all counts reside in the off-diagonal cells (zero's on the diagonal);
marginal frequencies remain the same;
the value of Chi square is maximal.
I can imagine a very 'exhaustive' approach by calculating the Chi squa... |
Does every Ordinary Least Squares (OLS) regression model have to pass both the Pregibon Test for Linearity (sometimes called link-test) and the Ramsey RESET tests?
I am working on an OLS model and it passes the Pregibon test when I include all the variables I wanted without squared terms. However, it fails to pass the ... |
I'm fitting a multiple linear regression model between 4 categorical variables (with 4 levels each) and a numerical output. My dataset has 43 observations.
Regression gives me the following $p$-values from the $t$-test for every slope coefficient: $.15, .67, .27, .02$. Thus, the coefficient for the 4th predictor is sig... |
Following the question here, how to I refer to GLM in my project?
Just a recap:
GLM is a general model that includes a number of regression techniques. I have used it to test the main effects of IVs (continuous and categorical) on the DV and also the IV-IV interactive effect on the DV.
I am confused about whether I sh... |
I have independent observations $Y_1, Y_2, ...., Y_n$ that take values 1 or 0 with
$$P(Y_i = 1) = \frac{1}{1 + \exp\{-(\alpha + \beta x_i)\}}$$
where $\alpha$ and $\beta$ are unknown constant and $x_1, x_2, ....,x_n$ are known, I have to show that $(\sum Y_i,\sum x_i Y_i)$is a minimal sufficient statistics for $(\alph... |
I have generated a 95% confidence interval $(22,25)$ for a parameter using a nonparametric bootstrapping method. What I want to know is what value we use for the estimate of the parameter.
Is it the mean of all the bootstraps, the median of all the bootstraps, the original estimate before we bootstrapped from the orig... |
this is, I think, an easy question... I did a regression analysis in R, where I wanted to check the fit of my data to a specific formula I provided... I got this to work, I see the graph and the line showing the fit of the data, but I also would like to get actual regression value obtained from this calculation, how do... |
I've tried some recursive moving average formulae (to reuse a previous output instead of summing the whole n-long set for every i) I've managed to find but none of them produces the same results as a bare moving mean does. Is there a reliable recursive formula which would produce exactly (or almost exactly) the same ou... |
I am running a model using lm in R to look at the effects of two independent factors. These independent factors are breeding group (bgrp: 2 levels with bgrp1=maternal lines; bgrp2=terminal lines) and sex (psex: 2 levels with psex1=males; psex2=females); and using number of total born (tb) as a linear covariate. I have ... |
Say I have a dataset that contains Users & all the sites that each user visited & how often each user visited it. For example:
User1 -> (Site1, 5 times), (Site5, 3 times)
User2 -> (Site2, 10 times) & so on..
Now based on how may times a user visited each site, I need to come up with a rating in the scale of 1 thru 5... |
Consider a study looking at the relationship of chili-pepper plant height to number of chilies produced.
Data was collected on all plants taller than 10cm. Initial look at the distribution of heights shows that most plants are on the short end, with a few reaching a max height of 150 cm as seen in a histogram. Taking ... |
I intend to apply Kevin Murphy's Hidden markov model (HMM) toolbox. I have a set of production rules(arbitrary) $A_0 \to AB [p=1]$, $A\to aC [p=1]$, $B\to bbC [p=0.5]$, $B\to b [p=0.5]$ where $A_0$ is the start symbol, A, B, C are the non terminals, and a and b are the terminals and the probabilities are put in bracket... |
Thank you for you guys effort on building such a nice community and I learned lot by reading and asking.
Background about my logistic regression:
Target Variable: Binary target about volatility of market. "1" for trading days with top 15% percentile volatility day which indicates the extreme day on market. "0" for res... |
I'm trying to educate myself on Granger Causality. I've read the posts on this site and several good articles online. I also came across a very helpful tool, the Bivariate Granger Causality - Free Statistics Calculator, that allows you to enter your time series and calculate the Granger Stats. Below, is the output fr... |
What are good introductory books on Kalman filters? I like lots of examples and practical techniques, and less theory.
|
If I am given the count of users participating in a forum thread on a continuous number of days, how can I can find the probability that a number of users will participate in the same thread on another given day in the future?
|
Example: I want to compare the number of successes in a sample of ~10,000,000 independent bernoulli trials against a known population probability of success of ~.01. Thus, expected success count for 10,000,000 trials should be 100,000.
What's the quickest hypothesis test to implement for a large n, small p? I would p... |
I have just started playing around and reading about Bayes Nets. Here is a snippet of code using the bnlearn package in R, which seems to be a fantastic tool.
install.packages("bnlearn")
library(bnlearn)
data <- data.frame(matrix(c("sunny","hot","high","weak","no",
"sunny","hot","high","strong","no",
... |
I am trying to do a grid search for a polynomial kernel. I have used the normal grid search on polynomial kernels which is wrong. I only varied $c$ and $\gamma$... but I need to vary $a$ and $b$... Is there any fast method to do grid search for polynomial kernels?
Polynomial kernel: $K(x_i, x_j) = (\gamma x_i x_j + a)... |
I'm having some trouble getting the NM Simplex to find a good minimum for selecting hyperparameters of a rbf SVC. Not only am I tuning the 2 SVC parameters (C and gamma) I also have five class weights that I'm trying to tune. Grid searches seem fairly infeasible in this case. The NM Simplex doesn't seem test inputs far... |
I have two versions of the same question:
Given a list of numbers (with possible duplicates), how to find a k-subset (with possible duplicates) that maximize the variance? is there a more efficient way than the obvious "check-all-k-subsets"?
Given a set of numbers, how do I select from that set a list of k numbers th... |
Very close to: Joint Gaussian of two Gaussians
I am trying to find the Bayesian classifier for two classes given by the following bivariate Gaussian distributions:
$$p(x|c_1) = N(\mu_1, \Sigma_1)$$
$$p(x|c_2) = N(\mu_2, \Sigma_2)$$
What is the formula and the methodology I should use to do this? I am confused with ou... |
I was struggling to find some solution of my problem which is as below:
Let say, I have 20 groups and for each group I have say 10the percentile value. Then is it anyway possible to calculate the 10th percentile for the combined group using those 20 individual 10th percentile?
If there is not any exact solution then an... |
I am new to time series analysis and I would appreciate if anyone could provide me some insight on it.
I am trying to analyse a past series of numbers that fluctuates between 107 & 210 with a normal frequency bell curve distribution of mean 162.
What is a suitable approach to forecast short-term future range for a tren... |
I've run a small experiment and need to test the data by comparing the frequencies of different treatments, specifically, whether they are significantly different. I think the chi-squared test is appropriate, but I am not sure how to execute it because it's somewhat outside the range of my course.
Simplifying, the data... |
Given two time series within the same time period, I can use the ccf function in R to compute a notion of similarity of these time series. What I am wondering is this - can I compute the cross correlation on the trend line obtained after using time decomposition function such as stl?
Time series decomposition is known... |
Let us say I extract all tweets containing a certain hashtag (main subject of the tweet) and bin them by the hour i.e. count the number of tweets that occurred during a certain hour. I will then be obtaining a time series for this particular hashtag. I have recently come across the STL decomposition which decomposes a ... |
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