1
vote
0answers
18 views

aov() and lme() give completely different results in analyzing repeated measures

I have data consisting of two measures per subject (variable score, measured at Day 0, and Day1 per each subject). There are two groups, and each subject belongs to one of them (variable Group). I ...
1
vote
0answers
34 views

Is there a statistically significant difference between two methods, which test should I use & am I violating random assumption?

I collected data for every 2016 Republican primary that has available at least 3 polls, according to the polling data aggregated by RealClearPolitics.com. In a spreadsheet for each row which indicates ...
1
vote
0answers
37 views

Model selection in binary logistic regression

I have 3 possible "final" models in binary logistic regression (N=176, Number of events = 36). Now I am trying to decide which one to select. It´s clear,"All models are wrong, but some are useful", ...
0
votes
0answers
7 views

Set minimum Leaf size for ctree [on hold]

Is there a method to set the minimum number of samples (leaf size) using ctree (library party) in R cran?
0
votes
0answers
14 views

Predicting the status of an individual across time [on hold]

In my case my training data frame is like the following : Id|Month|Status|Others 1|01/16|O|X 2|01/16|O|X 3|01/16|O|X 1|02/16|E|X 2|02/16|O|X 3|02/16|F|X 1|03/16|E|X 2|03/16|O|X 3|03/16|F|X ...
1
vote
0answers
12 views

Is a factor solution with a Heywood case considered legitimate?

I read in an SAS manual consulted here that "Factor analysts disagree about whether or not a factor solution with a Heywood case can be considered legitimate." I was wondering if someone could develop ...
0
votes
0answers
3 views

What does quantile parameter represent in estimate_bandwidth during Mean Shift Clustering?

I was doing Mean Shift clustering in a set of data with Python Scikit learn.We need to estimate bandwidth during Mean shift clustering.But what does the parameter quantile in the function ...
0
votes
0answers
7 views

How to calculate variance inflation factor (VIF) for a GLMER?

I've never worked with GLMER models before and I was wondering if calculating VIF is in any way different than in simpler regressions. In R, for instance, I usually use the ...
0
votes
0answers
16 views

How to automate linear model in R [on hold]

I have a data wherein for a specific brand weekly promotional information are there along with its sales. Now while running a linear model we generally look at the desired signs of the variable along ...
0
votes
1answer
30 views

How to determine seasonality of a binary variable?

I have a dependent binary variable Y, and an independent date variable X. I want to find out if there is any seasonality (at the year level). A few notes: The binary variable is in my model ...
0
votes
1answer
14 views

How can I export PCA output data in SPSS? [on hold]

I have performed a PCA to reduce the number of variables in my dataset. Now I want to have new dataset with reduced dimension to perform further regression analysis with other variables. How can I do ...
0
votes
0answers
17 views

Determining multiple linear regression scores

How do you determine (or extract if already given as an output) the X and Y scores from a multiple linear regression model i.e. in the new space (e.g. using typical linear regression packages in R)? ...
1
vote
1answer
21 views

How does trend stationary recovers from shocks in long run?

I was trying to understand difference between drift and trend wherein I came across concepts of unit roots and trend stationary. (I haven't read any books on time series, just going through web). ...
0
votes
0answers
5 views

How to deal with continuous variables with NULL values in prediction tasks?

I'm currently working on a machine learning project, trying to predict the expected revenue from a specific user. I have a long list of features that display the date when the user first performed a ...
0
votes
0answers
10 views

How can I import these .dat data-sets into R and/or Stata? [on hold]

There are some datasets (gss1.dat,gss2.dat,etc.) in this link, and I want to import them to the programs I'm using (R and Stata).They are contingency tables, in the form of scattered numbers. Could ...
1
vote
3answers
103 views

How linear regression can be used - explanation for grandmothers

Educational question. Suppose you have to explain linear regression to your granny. She is well educated, she knows even the idea of the hypothesis testing, but before you start to tell her what ...
0
votes
0answers
27 views

Regression ceoff. p-value as a 'summary measure' of 'indication of relative importance'

I have a paper in front of me (peer reviewed, etc.), which states "comparison of the P values for [the covariates] gives a good indication of the relative importance of each [covariate] for ...
1
vote
0answers
12 views

How to add stochastic drift in dynamic linear model?

As I'm not able to comment (yet), my question follows the one raised by @mzuba here I would like to use the DLM R package to model the local linear trend model, which unlike mzuba specified, has a ...
0
votes
0answers
16 views

optimism-corrected regression coefficients?

I used a regularized (LASSO) cox regression to estimate relapse times of patients and used Frank Harrell's bootstrapping method to obtain an optimism-corrected performance estimate of my model. I am ...
0
votes
0answers
16 views

Jensen Shannon Distance Bounds

I am calculating and graphing various distances between probability distributions. I am really confused about the bounds of the Jensen-Shannon Distance. I read somewhere that the Jensen-Shannon ...
0
votes
0answers
22 views

Monte Carlo conditional pdf

I have a question which as been bothering me. It's best explained by way of a dumb example: Suppose one wants to compute the value of pi by sampling within the unit square (i.e. ...
0
votes
0answers
30 views

Role of Central Limit Theorem in creating confidence intervals and hypothesis testing

How is central limit theorem useful in creating confidence intervals as well as its role in hypothesis testing around the population parameter.
0
votes
0answers
45 views

who can explain the gradient descent to a not -mathematician [on hold]

I'm trying to get a better understanding of a neural network backpropagation neural network and especially the gradient descent. I'm not a mathematician so I can't read or understand the formula's who ...
-1
votes
0answers
22 views

which one is more Efficient estimator on a given data set? [on hold]

I want to know "effiency of estimator" using R or "Relative efficiency of estimators", Here i have 7 co-variance matrix estimators, i want to know which one performed more efficiently then others... ...
2
votes
2answers
30 views

Bias of moment estimator of lognormal distribution

I am doing some numerical experiment that consists in sampling a lognormal distribution $X\sim\mathcal{LN}(\mu, \sigma)$, and trying to estimate the moments $\mathbb{E}[X^n]$ by two methods: Looking ...
2
votes
1answer
49 views

How does the support of a continuous random variable change under transformations?

Let $X_1$, $X_2$ have a joint pdf and support set $S$. Suppose random variables $Y_1$, $Y_2$ are given by $Y_1=u_1(X_1,X_2)$, $Y_2=u_2(X_1,X_2)$ where the functions define one to one transformation ...
0
votes
0answers
4 views

Comparing between group HR for different age strata

I was asked by a colleague if i knew how to test if between group (cases and controls) HR were higher in one age strata than in another. The design: Matched cohorts of cases (with info on debut age) ...
0
votes
0answers
19 views

Is HoltWinters() inferior to ets()? [on hold]

here is a simple R program using HoltWinters() function.it gives the following error message even for 100 iterations..(but run smoothly for smaller number of iterations)..But ets() handles the ...
0
votes
0answers
16 views

Should data be normalized before or after imputation of missing data?

I am working on a metabolomics data set of 81 samples x 407 variables with ~17% missing data. I would like to compare a number of imputation methods to see which is best for my data. Is there a ...
0
votes
0answers
7 views

Extended Cox regression time dependent variables

I have registry data for treatment with a certain drug for a large number of patients from the years 2005-2012. The main research question is whether the treatment is associated with higher mortality ...
10
votes
2answers
316 views

How do ABC and MCMC differ in their applications?

To my understanding Approximate Bayesian Computation (ABC) and Markov Chain Monte Carlo (MCMC) have very similar aims. Below I describe my understanding of these methods and how I perceive the ...
0
votes
1answer
7 views

exporting from R objects of class “gts” “hts” [on hold]

I am trying to save my forecast of class "gts" "hts" from R into excel but I get an error in R - "cannot coerce class "c("gts", "hts")" to a data.frame". Thank you, Despina
1
vote
1answer
18 views

What is the state-of-the-art non-parametric PDF estimation?

Below is some data points that are generated by a process that is normally distributed with $\mu=5$ and $\sigma=0.5$. But of course, we will pretend that we don't know the true distribution of the ...
1
vote
0answers
21 views

Numerical integration of a function of an empirical CDF

I have the following equation $y = f(x)$ and I want to invert $f(\cdot)$ to find $x$ numerically. Because the function $f(\cdot)$ is quite complex I will solve $y - f(x) = 0$ instead, using the ...
0
votes
1answer
18 views

Poisson regression with offset vs logistic regression

I am thinking to use Poisson regression with an offset variable instead of a logistic regression in case where event is rare, since p (probability of success) is very small and n (sample size is ...
0
votes
0answers
3 views

Can we do use convenience and purposive sampling at the same time?

Easy accessibility as the reason for choosing the participants but at the same time samples that have been purposely selected
0
votes
0answers
12 views

How to deal with interaction between several dummy variables and one continuous variables in one or two regression models?

I want to know the relationship between revenue and cost in several conditions. Dependent variables is REVENUE.REVENUE is a continuous variable from 0~1000+.I have several key independent variables: ...
0
votes
0answers
10 views

How to perform multiclass SVM classification using k-fold cross-validation and SMO with some kernel method in MATLAB?

I have data matrix X.csv file of size nxd, where n are the observations, and d variables. There are c_1,..., c_m classes. Let, Y be the matrix containing the class labels. There is no header row in ...
0
votes
0answers
23 views

Convergence in hidden markov model

I have a HMM where forward-backward probability increases in Iteration 1, then it decreases and then increases (as well as converges). Probability values after iterations 0,1,2,3,4 are: ...
0
votes
0answers
16 views

Proving that largest root (obtained via P.C.A.) is a symmetric function [on hold]

Suppose, we are given $\textbf{X} = (X_1, X_2, \ldots,X_m)$ and $\textbf{Y} = (Y_1, Y_2, \ldots, Y_n)$. Also, we are given, S = pooled variance. If we implement Principal Component Analysis (P.C.A.) ...
0
votes
3answers
57 views

What is the alternate hypothesis of the null hypothesis β_1=β_2=β_3=0?

Usually with simple hypotheses I will have something like $$H_0: \beta_1 = 0 | H_A: \beta_1 \ne 0$$ But suppose I have a null hypotheis $$H_0: \beta_1 = \beta_2 = \beta_3 = 0$$ Question What is ...
0
votes
0answers
12 views

Reduction of models

In a normal linear model, I have working with 3 categorical factors, $A, B, C$, and my main model is the interactions model $A*B*C$. My question is as follows: If i wanted to see how far I can ...
0
votes
0answers
10 views

Feature selection for an ordered logit model (R)

I'm using an ordered logit model to predict credit ratings/risk (1-8, ordinal) as a function of 126 predictor variables. (See: https://www.kaggle.com/c/prudential-life-insurance-assessment/data for ...
1
vote
0answers
27 views

Non-parametric density estimation: Is it better to estimate a PDF by first finding its CDF?

By better I mean fewer density error against the true PDF. Say that $X$ is the random variable that we wish to find its true PDF $f_X$ by the estimation $\hat f_X$. Then my goal is to find $\hat f_X$ ...
0
votes
0answers
20 views

Principal Component Analysis: Scale reliability and validity

I'm using a popular psychometric scale, the Domain Specific Risk Taking (DoSpeRT) scale, that contains 30 items that measure an individual's risk taking capacity across five different dimensions: ...
0
votes
1answer
23 views

What statistical tests to compare two AUCs from two models on the same dataset?

Let say I build two machine learning classifiers, A and B, on the same dataset. I obtain the ROC curves for both A and B, and the AUCs value. What statistical tests should I use to compare these ...
0
votes
0answers
11 views

Applying Cox Proportional Hazards Model on Discontinuous Variable

I am using coxph in Rstudio to apply Cox Proportional hazards model on my data. This model is easy to use on continuous variable ...
0
votes
2answers
31 views

Is this controversial that in PCA, we want the variance as large as possible, while in bayesian, a large variance means a low precision?

I am wondering about the variance. We say the variance is inverse proportional to precision, then we also say the variance is proportional to the information, which means that a large variance means ...
0
votes
0answers
11 views

Neural net and new data shape

I am studying machine learning, and trying to follow the neural net implementation in this book, but I am having problems with the net effectively rejecting the dimensions of my own dataset. In the ...
0
votes
0answers
5 views

R cut zero-length interval [migrated]

I have a column that has numeric values in the 1--7 range. I would like to use the cut function to split these values into the following intervals: 1 -> 1, ...

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