All Questions

11 views

How do I report an odds ratio approaching infinity?

I am analysing the association between several variables (e.g. sex, race, region, substance use etc.) which are categorical, to one baseline variable (past year cannabis use) which is binary ...
12 views

Checking Multivariate Gaussian (normal) distribution before applying LDA

I have a data set with multiple predictors. I want to apply Linear Discriminant analysis (LDA) on my data. But before doing that I must confirm that my data is from multivariate Gaussian Distribution ...
10 views

Dealing with missing data in Repeated Measures ANOVA

Hi :) I have a data set of comprised of: different subjects, each tested within subject (three time points) on a continuous scale, on various (unrelated) dependant measures. Some of these subjects ...
19 views

What is the ideal distribution for a GLM for comparing survey data with election results?

I'm relatively new to statistical methods. I'm hoping to learn what kind of distribution I should use for some data I have. My dependent variable is the results a candidate received by county. My ...
17 views

multivariate chi-square distribution R/Simulation

Is there some R package that calculate the quantiles\percentage of some vector of multivariate chi-square distribution? If there isn't can I simulate these percentage somehow? Thanks a lot.
18 views

Probability distribution arising from the combination of a normal variable and an other random variable

Let $X\backsim N(0,5^2)$ and Y be an independent random variable taking the values +1 and -1 with equal probability.Find the distribution of $S=XY+\frac{X}{Y}, T=XY-\frac{X}{Y}$ I have solved the ...
8 views

Fisher exact test in WGCNA

Then consensus analysis in R package WGCNA uses fisher exact test to check if two modules are significantly different. The input fisher.test uses are two logic vectors with the same length. The length ...
9 views

What is the best form (Gaussian, Multinomial) of Naive Bayes to use with (one-hot encoded) features?

I've been asked to use the Naive Bayes classifier to classify a couple of samples. My dataset had categorical features so I had to first encode them using a one-hot encoder but then I was at a loss ...
28 views

How do I check if a random variable follows the T Distribution?

Let us say I have a data for a random variable X -- Is there a convenient test that can tell me how well it fits the T distribution? Code in R would be helpful.
21 views

Difference between naive Bayes / multinomial / Bernoulli / SVM

i have a question to what consider the Naive Bayes algorithms, i am confused about the difference between the 3 algorithms: 1)The original Naive Bayes, 2)Bernoulli Naïve Bayes, 3)Multinomial Naive ...
46 views

Small sample size - repeated measure ANOVA or something more simple?

I have data from an ecological study on wasp abundance and diversity across a forest which I am trying to analyse appropriately. We have abundance and diversity data from ten locations that were ...
10 views

Checking whether a given formula is correct for a homogeneous Markov chain

I am new to cross validated so I hope my question belongs here. I saw in a paper where I study someone claiming the following: Given a $\{ X_n \}_{n=0}^{\infty}$ be a homogeneous Markov chain ...
11 views

Increasing PR curve?

Usually PR curves are decreasing (like as precision decreases, recall increases). How would you justify/interpret an increasing precision recall curve? The only way I can explain this is that the ...
20 views

Poisson or Linear Regression for Time Data

I am trying to model time-elapsed data (time from event A to event B) and am stuck on deciding between standard multiple linear regression vs. Poisson regression. A number of papers published on a ...
20 views

Rookie question about non parametric and parametric tests

I am a very rookie statistical test user and I want to better understand how to choose between a non parametric and parametric test based on my data. I read several statistical tests tutorials but I ...
17 views

Ranging [0,1] test set with parameters from training set

I am working on Machine Learning, particularly I have a dataset with 50+ columns and 100,000 rows. I need to get the data normalized with ranging to [0,1] (not with standardization) and I've split the ...
13 views

Grouping of two levels of a factor in R? [on hold]

I have a factor (diet) with 3 levels (ca, sa, comb) and a response variable (weight). I want to see how W changes in a group of the two first type of diets (ca and sa) compared to "comb". how can I ...
14 views

Problem on Mann Whitney U test statistic

Let $X_1$, $X_2$, $\ldots$, $X_m$ $\sim$ $N(\mu_1, \Sigma)$ and $Y_1$, $Y_2$, $\ldots$, $Y_n$ $\sim$ $N(\mu_2, \Sigma)$. (Here, $\Sigma$ is the variance-covariance matrix of the 2 multivariate Normal ...
25 views

Unexpected result when determining polynomial degree

I'm trying to determinate the best polynomial degree fits my dataset so I coded the follow script using LinearRegression with sklearn ...
8 views

Building a prediction raster when the statistical model was built from sampling units of different sizes

I would like to build a predictive map of capture success from a GAM. To build the GAM, I used data of capture success (dependent variable in the model) and proportions of land cover types ...
61 views

Maximum of a set of values from given mean and median

The arithmetic mean and median of $5$ distinct natural numbers are both $7$,what may be the maximum of the $5$ numbers? Here we see that the median is the $3rd$ value.Also the sum of the numbers is ...
13 views

How to read the output from MANOVA?

I'm testing if/how the two factors C and V affect the dependent variables fric and ...
487 views

Variable selection for predictive modeling really needed in 2016?

This question has been asked on CV some yrs ago, it seems worth a repost in light of 1) order of magnitude better computing technology (e.g. parallel computing, HPC etc) and 2) newer techniques, e.g. ...
8 views

Which of the followings can be regarded as sufficient statistics?

The probability of heads showing up upon tossing a certain coin is $p$, this coin is tossed $3$ times, let $X_i,i=1,2,3$ be $1$ or $-1$ depending on the outcome of the $i^{th}$ toss being head or ...
22 views

Problem on Principal Component Analysis (P.C.A.) [on hold]

Let $X \; = \; (X_1, X_2, \ldots, X_m)^T$ and $Y \; = \; (Y_1, Y_2, \ldots, Y_n)^T$. Let, $S$ = pooled variance-covariance matrix obtained from $X$ and $Y$. Let, $\alpha$ = principal component ...
27 views

Interpolate a CDF to get an interpolated hazard rate, or interpolate the hazard rate directly?

My problem is that I need to do an interpolation. Eventually, I will work on the hazard rate, but I do not know if it is better to interpolate the CDF or the hazard rate. Let me explain better. I've ...
5 views

Multilevel Analysis predicting level-1 outcomes with only level-2 factors, no level-1 factors

I am working on an analysis where I have 92 independent observations of TRAVEL, but (due to confidentiality constraints) the contextual variables have been aggregated to 18 clusters of 5 or 6 ...
13 views

Using the Naive Bayes classifier in R with continuous variables

I am trying to predict a categorical variable (type of job, there are three classes) using a dataset that mainly consists of continuous variables (like years of education, salary,etc), using the Naive ...
17 views

How to represent no-detection in a confusion matrix

So let's say we have a multi-class classification problem and we want to represent the outcomes as confusion matrix. All the examples I'm finding on the web asume that all the elements are detected. I ...
7 views

impute missing values for category variable in R [on hold]

Can somebody say how to impute missing values for category variables. There is a package called mice. However, it needs some method to entered, in order to impute the missing values. ...
21 views

Decision Tree Giving Impossible Splits

I ran a decision tree in SPSS, using the CHAID method. The result was a tree with many nodes. Some of the splits were impossible. For example: for a variable that is from 0 to 10 (in %), a split was ...
24 views

k-fold crossvalidation and independent models evaluation

I have a question about using k-fold cross-validation. From what I have read, there are several steps for using it. Shuffle my data. Train my model for each fold on training data and test it using ...
14 views

Unbiased estimate of a geometric random variable

A coin for which the probability of heads showing up on tossing it is $p$ is tossed $15$ times.The first head appeared in the 3rd toss and 6 heads showed up in $15$ tosses,what are the unbiased ...
5 views

anybody there who guide me about CFA in AMOS [on hold]

I want to run CFA on my data...my dependent variable is project management and independent variables are teamwork,trust,employee participation,human capital and training and development
43 views

how to generate random numbers ( using matlab or R) for mixed models [on hold]

g_1(x) ~ exp(2) g_2(x) ~ beta(5,2) Now I need to generate random numbers for g_α. α and sample-size will be passed as parameters. How do I generate random numbers. Additional info: I'm after the ...
10 views

How to predict individual coefficients and residuals with unbalanced panel data

I have a panel data with income for individuals over years, and I am interested in the income trends of individuals, and unexpected changes in income (i.e individual coefficients for income over ...