All Questions

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0answers
2 views

In Hidden Markov Model (HMM), is the transition matrix known, inferred, or assumed?

I'm reading Kevin Murphy's Probabilistic Machine Learning, which explains the forward algorithm to do filtering in HMM as follows (pp 610): The very first line says that the transition matrices ...
0
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0answers
2 views

Linear regression with redundant features (perfect multicolinearity)

Suppose $X \sim N(0,1)$, $Z=X$, and $Y=X$. An ordinary least squares regression problem is solved: $min_{(b1,b2)} \|Y-(b1*X+b_2*Z)\|_{2}^2$ This is a strictly convex function which must have a ...
0
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0answers
4 views

Can someone explain briefly application of PCA for estimating parameters in GMM

I am having some difficulty in seeing connection between PCA of second order moment and parameters of GMM ( mean components) . The claim is mean components are in the span of eigenvectors. Can some ...
1
vote
0answers
13 views

Tukey HSD, insignificant p-value when the confidence interval does not contain 0?

I am using TukeyHSD to do multiple comparisons. I am seeing strange results for some of the pairs: the adjusted p-value is greater than the specified significance level but the corresponding ...
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0answers
10 views

Issues plotting a fitted SVM model's decision boundary using ggplot2's stat_contour()

I'm trying to figure out how to plot a decision boundary for a fitted svm model in ggplot2. Right now, I'm attempting to do so by using stat_contour. Here is my code with an example call to my ...
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0answers
19 views

Arctangent, Tanh, Concavity.. How can I find the derivatives?

I want to find the first and second derivative (https://www.youtube.com/watch?v=dIE22eL6q90 (Inflection Points and Concavity Intuition video)) of a linear regression like this article shows ...
1
vote
1answer
20 views

How to use a linear model with two factors and repeated measures?

Suppose I have a date set of the form: ...
2
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0answers
12 views

Number of variables for decision trees

I have a data with just 5 independent variables and a response. I am dealing with a classification problem. Will decision trees perform well or the number of variables have to be higher to get ...
1
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1answer
27 views

Combining pca and classification algorithms

For some classification algorithms, assuming independence of data helps reduce the number of parameters to estimate. Why then not just to apply a method like pca or ica to the original features to get ...
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0answers
10 views

define prior probabilities in naive bayes with unbalanced classes and asymetric cost

I'm trying to apply Naive bayes to the following supervised problem: It's a binary classification problem The classes are unbalanced. The target class represents the 0.004266432 of the total and the ...
0
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0answers
18 views

Proving a linear model is not identified

Suppose there is a linear model: $$Y_i=\beta_0+\beta_1X_i+\varepsilon_i$$ How do I formally prove that without further assumptions $\beta_1$ is not identified. I thought to define a new set of ...
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0answers
2 views

Portfolio VaR with Copula?

Let the portfolio be given by: $$X=X_1+X_2$$ $(X_1,X_2)$ are dependent through a Copula function $C(u_1,u_2)$, such that the joint distribution is given by: $$F(x_1,x_2)=C(F(x_1),F(x_2))$$ What is ...
2
votes
1answer
21 views

What distribution is this? Activated process

A particle randomly hops a discrete distance from one position to another. I have measured, for 200 hops, the time between each hop. Here is the histogram: What distribution is this? To look at, ...
2
votes
3answers
128 views

Does mean = median imply that a unimodal distribution is symmetric?

For a unimodal distribution, if mean = median then is it sufficient to say that distribution is symmetric? Wikipedia says in relationship between mean and median: "If the distribution is ...
0
votes
1answer
14 views

Similarity datasets

Given two (or maybe more) datasets with the same samples/members, but with different variables. Is there a general way to compare the information available in the two datasets without looking into the ...
0
votes
1answer
11 views

Machine learning : learn feature value range for a classification

Which domain the problem belongs to? Given a set of products some are classified as cheap and some not. The task is to determine the price range (probablistic) for cheap products ? Supervised ...
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0answers
10 views

Sampling from a portion of the normal distribution?

I have a a conditional distribution $p(X_1 | \theta) \propto MVN(\mu, \Omega) \pi(X_1)$ where $X_1=[x_1, x_2, \dots, x_n]'$ and $\pi(X_1)=1$ when all $x_i \in [0,a)$ and $0$ otherwise. Is there any ...
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0answers
10 views

Survival Analysis on Telecom Churn in R

I am working on Telecom Churn problem and here is my dataset. http://www.sgi.com/tech/mlc/db/churn.data Names - http://www.sgi.com/tech/mlc/db/churn.names I'm new to survival analysis.Given the ...
0
votes
1answer
17 views

Unstandardize the slope of standardised variables in a linear regression

If I standardize my dependent and independent variable, and run a linear regression between them, the slope estimate which I have will be standardised. The variables were standardised by subtracting ...
-1
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0answers
7 views

SPSS one way ANOVA

I'm using SPSS version 20 in the statistical analysis of my study. It's a case-control study, within the cases there are three polymorphisms (TT, Tt, tt) and their correspondent vitamin D level. I ...
0
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0answers
20 views

How to check $H_0$ hypothesis using Pearson's criteria?

How to check hypothesis by using Pearson's criteria, that $H_0:$ random variable $X$ is normally distributed given that $k=7$ (count of intervals) and $\alpha=0.1 $ (significance level). I do ...
-1
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0answers
7 views

Likert Scale , SPSS and hypothesis

We made an online research that aimed to see if "have a pet" could influence "good perception about self". 69 participants answered 21 direct questions with this likert points (5.totally agree, ...
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0answers
4 views

Forcing a heteroskedastic error in R [on hold]

I'm looking assign a particular value to my error term (making it heteroskedastic) in a regression within R. How would I go about doing this? Thanks for your help.
0
votes
1answer
24 views

Machine Learning for Text Classification

I am new to Machine Learning.I am working on a project where the machine learning concept need to be applied. Problem Statement: I have large number(say 3000)key words.These need to be classified ...
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0answers
12 views

Conjugate Distribution for Tracy-Widom Distribution?

Does anybody know if there is a distribution conjugate to the Tracy-Widom (in the Bayesian context)?
1
vote
1answer
21 views

proving the asymptotic distribution of the mean

Let ${X_t} = \mu + \sum\limits_{j = - \infty }^{ + \infty } {{\psi _j}{\varepsilon _{t - j}}}$ with $\varepsilon$ is a white noise iid with variance $\sigma^2$ , $\sum\limits_{j = - \infty }^{ + ...
0
votes
0answers
29 views

What is bootstrapping

The bootstrap is a resampling method to estimate the sampling distribution of a statistic. This is what the tag description says on this website. I am a layman, can someone please help me understand ...
0
votes
0answers
13 views

NLP- Sentiment analysis

Most of solutions are based on training classifier to detect the sentiment of text. I am trying to analyze political reviews, I don't wanna divide my data on train/Test. What is the approach that ...
0
votes
0answers
17 views

Unsupervised learning algorithems to detect anomaly in waves

I have a sample of graphs (more then 10000...). that look like in the image below: I am searching an Unsupervised learning algorithems thet can help me to detect Anomaly observations. Here what i ...
0
votes
1answer
19 views

Fisher information always 0? What's wrong with this argument?

We exchange derivative and integral while proving that the expected value of the score is 0. Here is the proof which does so: \begin{align*} \int \left( \frac{\partial}{\partial \theta} \log ...
0
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0answers
13 views

How to evaluate this double summation (for a WLS regression) in MATLAB?

I asked this question a few days ago but deleted it as I thought I had solved the issue. I now realise that I had underestimated the problem at hand. The question is based on Ahn and Powell's (1993) ...
1
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0answers
3 views

Sample modification or weighting for partially paired data?

I want to analzye age and gender related differences of serum levels of an antibiotic agent, which was administered to 1200 patients during 1700 infectious episodes (1-12 infectious episodes and thus ...
0
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0answers
12 views

How can one go about recognizing a kind of motion using 3D depth data?

I'm using a Kinect device, and I'm currently extracting Joints, and Depth data unto probably a buffer data of 15 frames. This is done at 30 frames per second. The whole point of it is to try and ...
1
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0answers
15 views

Justifying the use of finite population correction

Given the fact the finite population correction effectively reduces the standard error of the sampling distribution, which (compared with the lack of a finite population correction) will increase the ...
0
votes
1answer
14 views

correlation and constant variable problem

I want to know if word length has an effect of being remembered or not by students. I conducted a test and entered each word as dichotomous variable (0-1, not remembered-remembered). However word ...
0
votes
1answer
12 views

Are VAR and VEC models theoretically neutral?

I have recently been introduced to Vector Autoregression (VAR) and Vector Error Correction (VEC) models in an Econometrics class, where both approaches were presented as a neutral way to test economic ...
1
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0answers
5 views

How to interpret standard errors and t-values in error-correction terms?

When estimating a Vector Error Correction (VEC) model in EViews, the resulting output always shows the error-correction terms together with standard errors and t-values for the included variables, and ...
1
vote
2answers
26 views

Choosing the number of principal components to retain before training a neural network for classification

I am working on neural networks and I am currently creating a perceptron that will work as a classifier for a data set of images with faces. I am required to perform pca (principal component analysis) ...
0
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0answers
6 views

Counting how many times some query parameters occur together

My web site logs which criteria was given by each search query. A typical line in this log file looks like x=foo&y=bar&z=baz, which means the user provided ...
0
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0answers
7 views

Minitab need help [on hold]

I need to create a comparison histogram using minitab. Anyone can teach me to the steps in doing that? EG
0
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0answers
21 views

Stochastic measuring of Poisson process

Railroad cars' lengths are distributed by $exp(\lambda)$. The train has n cars. We're standing $t$ length units from the beginning of the train, and we are measuring the car's length. What is the ...
0
votes
0answers
16 views

ANOVA result with insignificant factors

I'm having difficulty interpreting the result I get from ANOVA. Specifically, if some of the factors I put into the model have an insignificant impact (p-value > 0.05) on the output, does it mean I ...
1
vote
1answer
8 views

How to understand the “arriving rate” in a homogenous Poisson process?

We know that when the arriving rate of a Poisson process $X(t)$ becomes constant, then the process becomes a homogenous Poisson process. I have trouble understanding what "a constant arriving rate" ...
0
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0answers
22 views

A better fit for sinusoidal data

I have been struggling to fit my data to a sine curve. My data looks like: frame = data.frame(hour = c(0, 1, 2, ... 24), value = (numbers between 0 and 500)) I ...
0
votes
0answers
12 views

Area of Opportunity in C chart and U chart

In the article whether to use C chart of U chart is determined by area of opportunity.But I don't understand what is meant by area of opportunity and how it relates to C chart and U chart.Can ...
0
votes
0answers
9 views

R- Cost function in glm

I need to introduce a cost function in a logistic model (I'm using R). As I saw from this question, we can introduce costs in cv.glm. But I don't know how to introduce it in glm. My cost function ...
0
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0answers
13 views

[SOLVED]Is there a name for this simple discrete distribution? [duplicate]

I'm just wondering if there's a name for the distribution described by the following p.m.f $$p(n) = n(1-s)^{n-1}s^2$$ where $n$ is an integer from $1$ to $\infty$ and $0\lt s\lt1$. Thanks.
1
vote
0answers
9 views

Estimating mortality using Cox model with baseline

I have been reading online notes and papers on how to build survival models using CPH, and I think I've a good idea how things work. However, there are two questions I still have in mind: 1) let's ...
0
votes
0answers
9 views

Finding n and c in single sampling plan

I am learning a quality control course and in Single sampling scheme for attribute type inspection I don't understand the method used for calculating the values of $n$ and $c$. The method is as ...

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