2
votes
1answer
19 views

Conditional Binomial Question

Lost touch on some basics: $X \in Bin(n,p)$. Suppose that we know $P(X \ge l)$. Can we get a distribution for $P(X=x | X \ge l)$, $l \le n$? I would assume we use bayes rule and find $P(X=x, X \ge ...
0
votes
0answers
5 views

Efficient programming to overcome memory problem in R [migrated]

I have a function that calculates an index in R for a matrix of binary data. The function is: ...
0
votes
0answers
11 views

Extracting fixed-length feature vectors from variable-length time series

I have a classification problem where I would like to develop a binary classifier to classify between two different types of objects, given a time-series (signal) related to that object. The problem ...
1
vote
0answers
7 views

Plotting fraction of NAs of a data frame [migrated]

Does anyone know how to plot the graphs of figure 23.1 of the example chapter of Steyerberg's book? The R-function is called "na.plot2" and Displays for example the fraction of missing values in data ...
1
vote
0answers
14 views

Modeling Smooth Decay on Logarithmic Y

I have an empirical distribution that looks like the the image below and I hoping to model it with some parametric distribution. The X axis measures "number of ...
1
vote
2answers
56 views

what does it mean when out of sample AUC is greater than in sample AUC?

I am fitting a logistic regression model on a data set with about 200,000 observation and 100 features. According to SAS output, the model converged correctly with an in-sample AUC of 0.85. However, ...
0
votes
1answer
10 views

Requirements for a valid neural network activation function?

What rules define a valid neural network activation function, excluding biological plausibility? What set of principles do softmax, rectified linear units, hyperbolic tangent, sigmoid, etc. follow? ...
3
votes
0answers
10 views

Bayesian modeling with multivariate normal

Suppose you have an explanatory variable ${\bf{X}} = \left(X(s_{1}),\ldots,X(s_{n})\right)$ where $s$ represents a given coordinate. You also have a response variable ${\bf{Y}} = ...
2
votes
2answers
36 views

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?
2
votes
0answers
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 ...
2
votes
1answer
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 ...
3
votes
1answer
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 ...
2
votes
0answers
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. ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
0
votes
1answer
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 ...
2
votes
2answers
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 ...
0
votes
1answer
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 ...
2
votes
2answers
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 ...
1
vote
0answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
14 views

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 ...
3
votes
1answer
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 ...
3
votes
2answers
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 ...
2
votes
0answers
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 ...
1
vote
0answers
15 views

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 ...
2
votes
1answer
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 ...
0
votes
1answer
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 ...
1
vote
0answers
7 views

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 ...
2
votes
1answer
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 ...
0
votes
1answer
42 views

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
0
votes
1answer
18 views

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 ...
0
votes
1answer
7 views

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 ...
1
vote
0answers
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 ...
0
votes
0answers
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 ...
1
vote
0answers
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 ...
1
vote
1answer
14 views

Comparing Graduation Rates

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 ...
0
votes
0answers
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 ...
0
votes
0answers
11 views

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! ...
2
votes
1answer
23 views

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 ...
2
votes
1answer
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 ...
1
vote
1answer
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 ...
0
votes
1answer
15 views

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, ...
0
votes
0answers
13 views

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 ...
0
votes
0answers
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 ...
2
votes
1answer
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 ...
0
votes
0answers
16 views

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 $\mu_0 \in (0,1)$ ...
0
votes
0answers
5 views

model average predictions in MuMIn [on hold]

This code is taken from the MuMIn package: ...
0
votes
0answers
20 views

Non-Parametric Density estimation with a positive variable [duplicate]

I’m struggling to find a way to represent a kernel density estimation with a nonnegative random variable. I have read a couple of articles tackling this issue; however I couldn’t implement it in R. I ...
1
vote
0answers
2 views

Dependent predictors with converse effects on the target

I am trying to create a predictive model for marketing in the natural gas field. The model is supposed to guess how probable it is to make a contract in that particular building given many internal ...

15 30 50 per page