0
votes
0answers
6 views

Does a lower t-stat suggest better evidence for rejection?

Say I have these two models: $y = \beta_0 +\beta_1x_1 + u$ $y = \beta_0 +\beta_1x_1 +\beta_2x_2 + u$ and the $p$ value for $H_0:\beta_1 = 0 $ with $\alpha = 10\%$ for both is less than 0.001, but ...
0
votes
0answers
7 views

Why report r-squared in Instrumental Variables Estimation?

I mean the the R-squared calculated such as in $R^2=1-\frac{RSS}{TSS}$ when you use the $RSS$ from the original structural model and not recalculation that you should do in order to do an F test. With ...
0
votes
0answers
2 views

Help in state and parameter estimation when a time series model excited by pseudo binary input

An IIR system is excited by a pseudorandom binary signal $z_n$. The output of the system is corrupted by zero mean additive white Gaussian noise and this is observed, i.e., $y_n = \mathbf{h^Ty_{n-1}} ...
0
votes
0answers
4 views

Akaike information criterion for categorical and numerical data

How should I compute AIC for categorical and for numeric variables in classification problems? I see in Chapter 6 of Zumel and Mount that they use AIC before they train classification algorithms ...
0
votes
0answers
3 views

Alternative to AIC for feature selection in classification

I want to know what are the most common methods for feature selection in classification problems (binary and mutli-class). I see in Chapter 6 of Zumel and Mount that they use AIC before they train ...
0
votes
0answers
6 views

Count Data Model, Poisson Distribution and Rounding?

In doing a count data model using a Possion distribution, should the estimate (output) be rounded (or the ceiling) if your target variable is always a whole number in the input training target data ...
0
votes
0answers
5 views

Scatterplot with two different categories of data

I have a text document containing three columns. One column is "sex", and each value is either "M" or "F". The other two columns contain numerical data (my explanatory variable and response ...
0
votes
0answers
6 views

Time series analysis for discontinous years

i have a data of measured values of pH in river water for two years 2004 and 2009 for each month. I want to see seasonal trend ie: are there similarity in summer , winter and monsoon for both year. ...
0
votes
0answers
3 views

Transforming Negatively Skewed Independent Groups

I have two independent groups, (roughly 30 in each) – and their performance on 3 different tasks, there are 10 scores in total for each group. The majority of them are negatively skewed so I know I ...
0
votes
0answers
3 views

Possible Stacking Orders [migrated]

I have a question about how to calculate the total number of stacking combinations possible given a set of constraints. Specifically, imagine I'm trying to make a linear stack of objects ...
1
vote
0answers
20 views
0
votes
0answers
19 views

Is there a bayesian approach to MSE that takes into account the full posterior?

I have three predictive models (regressions) which parameters are estimated by MCMC. Predictions are made over a test set of size $N$. Since I compare the models under different settings, I would like ...
0
votes
0answers
9 views

The probability of m out of K things being wrong with an error of ɛ

I have a homework question about a machine-learning algorithm that uses ensemble learning with simple majority voting. Assuming we have K hypotheses, each with an error ɛ, the question asks us to ...
0
votes
0answers
6 views

Choosing a line/plane to seperate two classes of binned data

In high energy physics I know it is common task to find the best separation point between two classes of binned data, usually signal and noise. This separation point is determined by making a ...
0
votes
0answers
12 views

Incorporating intraday data into end-of-day forecast

my target variable is observable intraday but I am interested only in EOD forecasts. I will denote the variable $\ y_{D,24}$ as the reading of interest for day D is ...
0
votes
0answers
4 views

Removing contrast effect in mixed modelling deletion test

I am doing a mixed, linear regression analysis and now want to conduct a series of deletion tests on my max model, where I test if there is a significant increase in deviance once an effect that binds ...
0
votes
0answers
9 views

An 'easy' exercise on conditional expectations and filtrations

I am struggling with the following exercise and hope that someone can explain me how to derive the solution: Let $ \Omega = ${a,b,c} with $\mathbb{Q}$({a}) = 1/2, $\mathbb{Q}$({b}) = 1/4 and ...
0
votes
0answers
9 views

Paired homogeneity test: Compare two regression coefficients in R

I have a question about paired homogeneity test. By using Cox regression analysis Im evaluating 2 new biomarkers (A and B) in association with a outcome (X). I developed 2 multivariable models and on ...
1
vote
0answers
20 views

Modelling flight delays with negative values

Modelling flight delays with negative values I am working on a model to predict whether a flight will be delayed. The data consists of some explanatory variables for flights from a specific airport. ...
0
votes
0answers
16 views

Multiple imputation of conditional variables

I need to impute the missing values of a dataset of medical data in which several variables only make sense if another variable has a specific value. In the questionnaire the data come from they were ...
0
votes
0answers
8 views

partial plots from a Random forest classifier for binary predictors

I'm working on a classification problem with continous and categorical predictors with Random Forests (RF). I'm particularly interested on RF as we avoid the specification of the functional form. ...
1
vote
1answer
40 views

Which distribution to use for a probability problem?

In a food processing plant, on average, 2 packaging machines breakdown per week. I let x be the number of processing machine breakdowns in a week. So x is Poisson(2), but one part of the question ...
0
votes
0answers
6 views

should we check for multicollinearity when building a discrimination analysis?

In fact, I have two questions: 1- do we need to check for the multicollinearity when we deal with linear discrimination analysis? 2- how to solve those variables which are multi-collinear? Lets ...
0
votes
0answers
9 views

How libsvm performs Cross Validation?

I wanted to know that whether libsvm performs cross validation by preserving the class ratios / label distribution within each fold? My train data is organized. For example if I have 20 training ...
2
votes
1answer
11 views

Advantages of counterbalancing vs. randomizing stimuli

I'm designing an experiment, in which 40 participants answer 10 questions, 5 in condition $A$ and 5 in condition $B$, and I'm interested in the difference between the two conditions. It's not clear ...
1
vote
0answers
21 views

Is sampling according to several i.i.d. random variables or to just one of them equivalent

Suppose we have n+1 random variables i.i.d. distributed $X_0,X_1,...X_{n}$. Is it the same operation if I generate n samples according to $X_0$ $\{S^0_1,S^0_2..,S^0_n\}$, or if I take from each of the ...
0
votes
0answers
18 views

structural break

Say I have the equation: $y_t = \alpha + \beta*\text{time}$ I'm looking for a structural break test that allows both parameters ($\alpha$ and $\beta$) to potentially change with a structural break. ...
-1
votes
0answers
13 views

Matrix Algebra (matrix/vector) [on hold]

I have this simple function : $$F=\frac{A\beta}{B},$$ where $A$ is $n\times n$ matrix of constants, $B$ is a $n\times 1$ vector of constants, $\beta$ is the parameters $1\times n$ vector. It is ...
1
vote
1answer
13 views

Data visualization tips for a 2x2 factorial design

The data stem from a 2x2-factorial design where both factors have two levels. The x-axis shows the words of a sentence and the y-axis the mean reaction time for each single word. Here is how I ...
-1
votes
0answers
25 views

Optimal brain damage in R

Is there any R package implementing optimal brain damage algorithm or anything similar what can be used to prune neural networks models?
1
vote
1answer
21 views

Can I apply factor analysis on multiple choice questions?

I am looking to validate a questionnaire and would like to know if I can use factor analysis on the multiple-choice questions (MCQ). Also, I have another section where I am asking about participants ...
1
vote
0answers
11 views

Treatment of mixed effect models for Box-Cox transformation

To analyse the Box-Cox plot in a mixed effect model, no simple transformation/ code in R exists. So which of the following approaches would be valid ways and why? 1) Take a random sample (say of size ...
1
vote
0answers
14 views

Creating a copy/simulation of a dataset respecting statistical properties?

I often need to work with and analyse electronic medical record data which cannot be moved from the servers in the organisation where it resides, due to ethical reasons. Is anyone aware of a method or ...
0
votes
0answers
11 views

When to use Bayesian Networks over other ML approaches?

I expect there may be no definitive answer to this question. But I have used a number of machine Learning algorithms in the past and am trying to learn about Bayesian Networks. I would like to ...
0
votes
1answer
21 views

Setting up a aov model in R for a variant of a 2-way nested ANOVA

I have a rather complex experiment i need to analyse The experiment was an infection trial, where the effect of two different infection methods ("inoculation" and "in-contact infection") were ...
2
votes
0answers
26 views

When should I say that error is high

I am a self-taught person and I would like your help. I am learning about predictive modeling in general, and I'm also trying to do predictive modeling for a specific problem. I am exploring ...
0
votes
1answer
14 views

Can we boosting or stacking with different input variables for each model in machine learning?

I have a question about Boosting and stacking in machine learning. Suppose that I will train neural network, SVM and logistic regression using optimization algorithm to optimize best inputs in first ...
0
votes
0answers
14 views

Fisher's linear discriminant VS naive bayes

i know some basic things about linear classifiers. i prefer two think geometrically about them. and what'll happening if covariance Matrix were different things. Generally; What's the difference of ...
0
votes
0answers
12 views

Clustering MVT response data by audience

We are doing multivariate testing 4 possible values for each of 3 variables on a landing page: (a) offer presented, (b) product claim message displayed and (c) image used. So, 12 dummy variables, 64 ...
-1
votes
0answers
19 views

Statistically prove that answers to questionnaire are not correlated to questions

I have a questionnaire of 4 "yes-no" questions: A1,A2,B1,B2. The correct answer for A1 and A2 is "yes", and the correct answer for B1 and B2 is "no". I need to statistically show the fact that ...
0
votes
0answers
9 views

Correlation between decision trees

How do you find the correlation between decision trees? I know this is an issue when working with random forests, but I can't find an explicit formula anywhere. I only get that random forest reduces ...
0
votes
0answers
13 views

Interpreting partial eta squared and reporting it apa style

How do you interpret and report partial eta-squared in a two-way anova? I have run a two-way anova to inspect whether gender and level of education interact to have an effect on positive affect. ...
0
votes
0answers
8 views

software or libraries to create document term matrix for arabic texts? [on hold]

Ideally I would like to analyze arabic texts without translating. Does anyone know any software or libraries for R or python that can make a document term matrix out of Arabic texts? Thanks.
1
vote
0answers
16 views

QQ plot in Python

I generated a qq plot using the following code. I know that qq plot is used to check whether the data is distributed normally or not. My question is what do the x and y axis labels indicate in qq plot ...
0
votes
1answer
12 views

What do you mean by pollster bias in an election?

I came across harvards election poll data science question. I which they ask: Is there a pollster bias in presidential election polls? What exactly is a pollster bias? can some one explain it to me in ...
-1
votes
0answers
9 views

statistics test to use with ordinal data [on hold]

If a group of people come into a room in a given order one day and we compare with the same group of people coming into the same room on another day and they enter in a different order. Each person is ...
0
votes
0answers
9 views

Gaussian Mixture Model with Custom Distance Metric

I have some 1D data that I want to cluster using Mixture of Gaussian. However, the data "wraps around" at two extremes. Specifically, I have a list of angles from $-\pi$ to $\pi$ and the data near two ...
0
votes
0answers
9 views

Is there a need for estimamting noise variance if it is an iid? [on hold]

it looks like noise variance does not need to be estimated if the noise is an iid, but on the other hand variance is constant if it is an iid? is white noise an iid? Please clarify.
1
vote
1answer
88 views

Why is there a E in the name EM algorithm?

I understand where the E step happens in the algorithm (as explicated in the math section below). In my mind, the key ingenuity of the algorithm is the use of the Jensen's inequality to create a lower ...
3
votes
0answers
26 views

How to do inference over two steps in a graphical model simultaneously?

Here is my problem: I have observed data $D$ about a physical object described by $M$. I would like to determine the posterior distribution of $M$ given $D$, or $p(M|D)$. Now I can't infer this ...

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