All Questions

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Meaning of the expression $P(\theta_1,\theta_2,\theta_3) \propto 1$?

I am reading this statistics books and it keeps on repeating same expression over and over again $P(\theta_1,\theta_2,\theta_3) \propto 1$ What does the above expression mean?
22 views

How to proof relationship between inverse covariance matrix and linear regression coefficients?

Edited: I would like to work out the above relationship, more precisely: Let $(Y_{1}, ..., Y_{m})$ be a zero-mean vector with covariance matrix $\Sigma$, and let $S \subset \{1, ..., m\}.$ The ...
34 views

How to find all optima in an optimization problem?

I have an optimization problem where several optima can exist at different input values, and I need to find as many as possible. As an example consider the cross-in-tray function, which has four ...
25 views

Manual calculation of variance-covariance from published confidence intervals

I would like to obtain the variance-covariance matrix from a published set of regression outputs. These outputs provide a mean value and confidence intervals. I will convert the confidence intervals ...
18 views

Are matrix Fisher r.v.s closed under multiplication?

With appropriate parameters, a matrix Fisher distribution provides a distribution over SO(3) (i.e. over rotations in $R^3$). See this MathOverflow post for a few notes describing the distribution. ...
18 views

Does Matlab neural network training speed up with a gpu [on hold]

I read that Matlab neural network training does not support GPU processing when using trainlm Matlab neural net training on GPU. Considering I use trainscg, how much faster can I expect the the ...
8 views

Estimating covariance for naive Bayes

I am a beginner in Pattern Recognition and started reading up Bayesian classifiers. I came across the case of naive Bayes with equal covariance in all dimensions. Given sufficient data, how does one ...
27 views

Interaction terms and effect sizes in multiple regression

I know there are similar questions on here, but I can't quite find an answer that covers all of what I need. I am running multiple regression in r with two predictor variables and sometimes an ...
59 views

Show that the value is, indeed, the MLE

Let $X_1, ... X_n$ i.i.d with pdf $$f(x;\theta)=\frac{x+1}{\theta(\theta+1)}\exp(-x/\theta), x>0, \theta >0$$ It is asked to find the MLE estimator for $\theta.$ The likelihood function is ...
10 views

Weka java API: Attribute Selection and Cross Validation

Is there a way to perform Attirbute selection(aka feature selection) (regardless of method) only for the training dataset before passing data for Cross Validation ? I currently think that the only ...
23 views

Regression problem without complete data set

I have a medium sized database of hands played at an online poker website. In poker, you starting hand can be classified into one of 169 different hole card combinations (e.g. AA , 87s which means ...
14 views

how to interpret Interaction term in generalized linear model [duplicate]

I have an experimental condition (dummy-coded) as an categorical predictor, and one continuous predictor variable (treatment frequency). The dependent variable (Y) is consumer satisfaction This is ...
12 views

TBATS missing value error

I used tbats to find the best fit model to a 3 years of daily data. It couldnt find a model and showed the following error: " Missing values encountered. Using longest contiguous portion of time ...
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How to decide whether a given probability problem requires order or not

When solving a probability problem or calculating "n choose k", I am having difficulty deciding whether problem requires order or not. Are there any general rules of thumb that I can use while reading ...
25 views

Question about definition of random sample

In my statistics class, we're just beginning to talk about (point) estimation. I have a small question that might actually be due more to notation/definition than anything very conceptual: Say you ...
62 views

Is my Bayesian analysis correct?

This is my first time doing a Bayesian analysis, so I'm not sure whether what I did makes perfect sense. I'm trying to tell if two samples come from the same distribution, more specifically, if they ...
38 views

What enforces features diversity in RBM?

I'm working on an implementation of a Restricted Boltzman Machine (RBM). I made some tests on the MNIST dataset trying to learn a representation of the digit 2. My inputs are binary images. My aim is ...
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Are pooled results from multiple imputation equivalent to a posterior mean?

I am fairly new to multiple imputation and trying to be sure I understand the approach. Say I have a data set with missing values, so I create 5 imputed data sets using multiple imputation by ...
46 views

Analyzing the effect of categorical variables on a correlation coefficient

For my research project, I’m looking for some help on how to analyze my data. The research setup is as follows: I’ve got two normal variables that I want to correlate with each other and a number of ...
24 views

Use fitted value from regression on subset of features as independent variable

I am working with a relatively large data set with 2K columns and many variables can be grouped together (a logistic regression). So I am thinking can I use fitted value from regression on subset of ...
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Selecting optimal model when only smoothed data available?

I have a graph of some (highly nonlinear) experimental spectrum which is obtained by smoothing results of several repeated measurements obtained by different experimental methods. The graph also ...
40 views

Find the degrees of freedom of a F distribution given its 97.5th percentile

Let's suppose I have a F distribution $f$ with unknown degrees of freedom $df_{numerator}=df_{denominator}=df$. If I know the 97.5th percentile $f_{0.975}$ such that $P(f>f_{0.975})=0.025$, is it ...
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Can multiple logistic regression be performed without a reference/baseline?

I was wondering of it's possible to perform a multiple logistic regression without a baseline reference. The analysis I'm dealing with doesn't have a "natural" baseline reference. Thanks in advance
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Is there any good reference which statistical test should be used given study design?

I am looking for a source (infographics, picture, graph, list, book, algorithm or whatever) that clarifies which statistical test should be used when. I mean what do I use when I have two unpaired ...
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Why are my q-values equal to 1 for differential expression of miRNAs across a categorical variable (0 and 1)?

I have a categorical variable that takes values 0 and 1. After doing differential expression of miRNAs (continuous variables), I performed FDR to adjust for multiple comparisons. My q-values turn out ...
35 views

chisq.test with R

I want to do a Goodness-of-Fit test of my data and the Weibull-distribution. I have estimated the Weibull distribution using the survreg-function in R. Now I want ...
29 views

Is the following statistical analysis valid/correct? And if so, what is it called?

I've used a method of statistical analysis based on my own insight to determine if age correlates with a variable X over time. Each participant has a different number of records for X with different ...
12 views

Persistence in GJR-GARCH (asymmetric GARCH)

Consider the standard GARCH model: $\sigma^2_t=\omega+\alpha\epsilon^2_{t-1}+\beta\sigma^2_{t-1}$. The so-called persistence parameter is defined as the sum $\alpha+\beta$. Now consider the ...
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I have multiple student graduation rates from the same school. Each year, there are variations in the student population and each year there are different graduation rates. Is there a way to compare ...
13 views

Partial pseudo $R^2$ with GLMs

Is a partial pseudo $R^2$ (pseudo $\eta^2$?) even a valid concept when dealing with a GLM? This, of course, presumes that partial pseudo $R^2$ is valid at all. If it is valid, how would one go about ...
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How do I add spaces in between the labels on the y axis as well as move the y axis label to the far left so it wont clash with the text [on hold]

How do I add spaces between the labels on the y axis as well as move the y axis label to the far left to avoid clashing as can be seen in the image below. The programme I am using is R. Please help! ...
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Does the ratio fallacy apply when calculating a Pearson's correlation between one ratio variable and one absolute variable (no common term)?

Am I committing the ratio fallacy when I calculate the Pearson's correlation between a variable x/y and a variable z, with no common terms? I have found a similar question to mine here but the reader ...
38 views

How to evaluate collinearity or correlation of predictors in logistic regression?

In linear regression it is possible to render predictors insignificant due to multicollinearity, as discussed in this question: How can a regression be significant yet all predictors be ...
21 views

Mixed ANOVA post hoc analysis (and multiple comparisons)

I have a set of 12 subjects: 6 administred with drug A and 6 with drug B. For each subject two time-points have been collected (before and after drug treatment) for each analyte (over 6000). I had a ...
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how to estimate heterogeneous effects?

I have a dataset where I run regression discontinuity with the following code: xi: reg work post i.post|m i.post|m2 age age2 age3 immig primary hsgrad univ sib pleave i.q if m>-10 & m<9, ...
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Unbalanced groups in a Hierarchical Linear Model

I would appreciate some practical and/or conceptual advice on sample sizes in a two level hierarchical linear model. A lot of the material on sample sizes and HLM is about the number of level 2 ...
15 views

how one independent variable affects other variable in multiple regression

I have a two independent predictors in regression equation "X1" and "X2". X2 is categorical hence 1,0 is the allowed values. I have to find how X1 get affected based on value in X2 in following ...
11 views

Null hypothesis of probit model Wald test

Say I estimate the following probit model: $$ins = \Phi(\alpha + \beta_1 age + \beta_2 educ + \beta_3 hg + \beta_4chronic + \beta_5 hisp + \beta_6 lin) + u$$ where: $ins = 1$ for any individual who ...
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Bayesian Updating Process, 3 signals and 2 states of the world

Suppose Nature chooses a state $\omega = \{X,Y\}$ at $t=0$. Long-lived agents observe a signal $s_t$ at every period $t$, where $s_t = \{ x,y,z \}$. Agents all hold a common prior $\mu_0 \in (0,1)$ ...
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model average predictions in MuMIn [on hold]

This code is taken from the MuMIn package: ...