# All Questions

32 views

### p-value for weighted Pearson correlation coefficient

I'm computing a weighted correlation coefficient, using the method described here. I'd like to compute a p-value for the resulting r coefficient. How can I do this correctly, given that my r was ...
16 views

### How to obtain the complete model matrix of a mixed model?

Suppose I have a mixed model like this: ...
6 views

### Rearranging 2 discriminant function to solve for 1 parameter (to derive a decision boundary)

I have a task where I want to classify patterns from 2 classes where the samples are drawn from a bivariate Gaussian distribution. I use the 2 discriminant functions ($g_1$ and $g_2$) to classify the ...
30 views

### Measuring Statistical Significance of Binary Classification using Matthews Correlation Coefficient

Based on the following relationship between Matthew's Correlation Coefficient (MCC) and Chi Square: (MCC is the Pearson product-moment Correlation Coefficient) Is it possible to conclude that: By ...
27 views

### Hypergeometric Distribution Question

I am currently doing a self-study question that gave me the following scenario: There are 10 marbles in a jar. 7 marbles are red while 3 are blue. John wants to pick 4 marbles out to give his friend. ...
15 views

### test for variance by using chi square test in R

how can i know if these data -> 93, 91, 93, 150, 80, 104, 128, 83, 88, 95, 94, 97 58, 139, 91 provide evidence that the pop variance is greater than 0.05 (a=0.05) by chi square test in R? please ...
105 views

### Why is optimizing a mixture of Gaussian directly computationally hard?

Consider the log likelihood of a mixture of guassians: $$l(S_n; \theta) = \sum^n_{t=1}logP(x^{(t)}|\theta) = \sum^n_{t=1}log\sum^k_{i=1}p_iP(x^{(t)}|\mu^{(i)}, \sigma^2_i)$$ I was wondering why it ...
12 views

### About penalty setting in package changepoint

I have read the documentation for this package,but there is one place I don't understand, in page 7 the author set the penalty value to 1.5*log(n), where does this "log(n)" originate from? A bracket ...
17 views

### data representation with nominal, ordinal and continuous variables

Suppose I have data of this format: customer, country, location, unit price (discrete set), traffic, etc. (more nominal/ordinal variables) I want to know how country affects unit price, how do I go ...
97 views

### Exponential Distribution PDF: Why multiply by lambda?

Hoping you can help me understand the probability density function for the exponential distribution. Given that the distribution's PDF is described as follows when x > 0: $$\lambda e^{-\lambda x}$$ ...
9 views

### How do i read only lines that fulfil a condition from a csv into R? [migrated]

I am trying to read a large csv file into R. Even though the file is large, I only want to work with some of the rows that fulfil a particular condition (e.g. Variable2 >= 3). This is a much smaller ...
20 views

### Understanding stationarity with Inflation

Good afternoon, Apologies if this question is basic, I have done a lot of research, but haven't found a definitive answer online and so I'm hoping someone might be able to help me here. I am looking ...
21 views

### How do we use logistic regression (scikit-learn) to predict values

Logistic regression can help to predict a value whether it would happen or no. I'd like to know how can I do that using sklearn. I'd like to know the probability if this event would happen or no. I ...
28 views

### Trouble fitting a simple linear regression

I have been trying to do a simple linear regression of x3=Weeks Claimed against x4=Weeks compensated. I am having problems because my residual standard error is very high and also my residuals are ...
6 views

26 views

### Decision Tree - Splitting Factor Variables

I'm new to decision trees and I have some confusion about how factor variables and non-ordered character/string variables get handled in a split. Suppose I have a factor such as "tiny, small, medium, ...
19 views

### HMM learning from video data?

I am having a problem understanding how to learn the parameters for the HMM from observed data. Let's say that my HMM model has one hidden variable for affect(emotion) with three values/states (anger, ...
9 views

### How to get overlapping edges using igraph? [migrated]

I am trying to create a network graph with overlapping edges. ...
40 views

### lm() function in R

This is kind of a follow-up question from this post: Gradient descent vs lm() function in R? Is there any literature available for the QR decomposition concept involved in the ...
28 views

### Correlation & Regression Prediction [on hold]

I have a homework question. I have solved most of it already, but am unsure how to proceed with one specific part that involves prediction (Parts B & C). I am not looking for anyone to just give ...
11 views

### How to normalize interaction terms?

I'm training a classifier for a supervised classification problem. Some of my features interact, how should I normalize these interaction terms? For example, if x1 and x2 interact, the interaction ...
15 views

### How to graph interaction effects for panel data

I have a pretty generic question which I am guessing could be relevant to many social scientists who deal with panel data sets. What are the best practices for making graphs about interaction effects. ...
48 views

### Linear Regression Real Life Example

I am learning Machine Learning(Linear Regression) from Prof. Andrew's lecture. While listening when to use normal equation vs gradient descent, he says when our features number is very high(like 10E6) ...
13 views

### Are Restricted Boltzmann Machines better than Stacked Auto encoders and why?

So I'm learning about deep learning. I first learned about stacked auto-encoders and now I'm learning about Restricted Boltzmann Machines. However non in the papers/tutorials I read I found them ...
18 views

### Why is the decision function for probabilistic models a quotient (when we only consider two models)?

Take for example, that we want to find the probabilistic model for only two document types (doc can be + or -). I was trying to understand why the way that we classify a document model was with the ...
22 views

### decision boundary of support vector machine when data is not linearly separable

Screenshot from this video: This describes the decision boundary of support vector machine as a optimization problem with two constraints. But it seems to assume that the data points are linearly ...
45 views

### How do we analyse likelihood in a dataset? [on hold]

I am working to analyze poverty rate using census data. I have a huge dataset. I want to extract the likelihood from this dataset in order to create patterns for energy consumption. What is the ...
139 views

### How to do multivariate machine learning? (predicting multiple dependent variables)

I am looking to predict groups of items that someone will purchase... i.e., I have multiple, colinear dependent variables. Rather than building 7 or so independent models to predict the probability ...
19 views

### Intuition behind (statistical) completeness

I was wondering if any of the members of this community would like to share his/her intuition about completeness in statistics. For the sake of "completeness", here's the definition, taken from ...