# All Questions

16 views

### Chi-square test for interaction

I want to look at the interaction between two independent variables on a binary dependent variable. I can't use a binary logistic regression because I have a small sample size. Can I do this using a ...
19 views

### Clustering Moving Objects

I'm new on clustering algorithms. I have a data of moving objects generated in time Series. The data generated on equal time interval (1 observation per second). The only information I have about ...
10 views

### How to measure loss of performance of clustering by applying dimensionnality reduction

Let's suppose I have a given dataset whit $n$ features. Having a data-centric approach, I would like to measure the loss of performance of applying a given dimensionnality reduction technique, for a ...
8 views

### Feature Extraction for landscape images

I work on a landscape-image database (forests, beaches, landmarks, cities etc.) and I'm trying to find the similarity between them, I don't have labels or any specific classes, I just want to find ...
24 views

### Using standard errors of coefficient as goodness of fit or to calculate standard error of the regression

I have performed a regression analysis and on top of computing the coefficients, confidence intervals, and significance, I have the standard errors. I have been asked to provide a numerical estimate ...
51 views

### How are outliers dealt with in R after detected? [on hold]

Once outliers in time series are detected in R how exactly are they dealt with before forecasting? I dont want commands to use i would like the method. Please do not give any answers to do with ...
40 views

### Residuals - What are they? How can i obtain them?

So, i have a data set. I decide to fit an AR(1) model to it thus obtaining a model of the form $X_t - \hat{\phi} X_{t-1} = Z_t \quad Z_t$ is $WN(0,\hat{\sigma^2})$ Which in matlab is given by ...
18 views

### Restrictions implied by the null hypothesis

Suppose, we are testing $H_0:\theta\in\Theta_0$ against $H_a:\theta\in\Theta_1$, $\Theta_0\cap\Theta_1=\emptyset$ and $\Theta_0\cup\Theta_1=\Theta$, the whole parameter space. I have seen two ...
14 views

### Testing proportion differences on multi sample/multi category data

My data is like this: I collected three groups of data randomly collected from three groups: A:(Age < 20), B:(Age 30-50) , C:(Age > 50) I evaluated the level of people smokes with three categories ...
36 views

### How should one assess model fit for non-linear regression?

I am looking at non linear regression. Below is some example output from a non linear regression using MATLAB. There are also two links below this output from the Minitab website. The links explain ...
67 views

### Confidence Interval Calculation

I have temperature data of July 1991 to 2007, and wants to find the Confidence Interval at 95%, which distribution is best fit the data, Z or T. Please give me reason also. minTemp = 14.4444, ...
6 views

### parameter estimation of Gompertz distribution [on hold]

What kind of package in R for parameter estimation by the method of Weighted Least Square on Gompertz distribution? Also give an example for using that package.
20 views

### Confidence Interval Calculation [duplicate]

I have temperature data of July 1991 to 2007, and wants to find the Confidence Interval at 95%, which distribution is best fit the data, Z or T. Please give me reason also. Thanks
28 views

### How to demonstrate biased estimates of linear regression vs cox proportional hazard survival analysis in R?

I want to perform a really simple simulation of right censored data. Then I want to draw a kaplan meir survival curve and do a cox proportional hazards test. Then I also want to perform a simple ...
38 views

### How do you get the principal components of one matrix along the principal directions of another matrix?

I have a data matrix, A, on which I have performed principal component analysis (PCA) using the prcomp function in R. This gives me the ...
53 views

### t-statistic vs two-sample t-tests

When and in which context is the t-statistic used? $t = \frac{\hat{\beta} - \beta_0}{se(\hat{\beta})}$ where $\beta_0$ is a non-random, known constant, which defines the null-hypothesis in the ...
13 views

### Is there a generic expression to represent the multiplication of a distribution? [on hold]

Let say a value N >> 1 is distributed among m>1 members, which can follow some distribution (Binomial or Gaussian). Is there any generic term to represent the multiplication of the distribution. For ...
9 views

### enumerating patterns in a set of contingency tables

I have a set of 3X3 contingency tables and want to identify the distribution of the patterns by comparing their expected and observed number of samples in each cell using a right statistical test. For ...
26 views

### Classification trees: the best Predictor and the ability to predict

The topmost decision node, the root node in a classification tree is said to be the best predictor of the model. Does this mean the root node variable is also the best in predicting the target ...
27 views

### Help in choosing the machine learning algorithm for gaze estimation [on hold]

I am trying to build a program for gaze estimation for gaze based human computer interface from the x and y coordinates of the pupil centres of the eyes by capturing video through webcam.(x and y ...
22 views

### How to simulate noisy respondent entry of short textual responses? [on hold]

I have a list of company name as following: ...
7 views

### interaction effect on consecutive gestures from different sets

I am conducting an within-subject experiment in which each participant has to perform 2 consecutive gestures with one arm. (with repetitions). To make it simple, let's say that I have 2 sets of ...
70 views

### Interpreting prior and posterior

I am bit puzzled on how we can interpret the posterior. Assume a coin which is 0.1 probable to be unfair. So our prior probability on the coin being unfair is 0.1, and being fair is 0.9. Also by ...
22 views

### Computing Issues with Kriging

I am having some issues with Kriging in R, and I was looking for some idea where I am going wrong. From what I can tell, I done a decent job removing the trend, and I believe my transformed data is ...
49 views

### Do we need to adjust sampling weight in logistic regression?

Suppose, I am using malnutrition data from Demographic and Health Survey. This survey used multistage cluster sampling. Here is a sampling weight (probability weight). If I want to say nationally ...
54 views

### What is a Highest Density Region (HDR)?

In statistical inference, problem 9.6b, a "Highest Density Region (HDR)" is mentioned. However, I didn't find the definition of this term in the book. One similar term is the Highest Posterior ...
125 views

### Minimization of the Sum of Absolute Deviations

My particular task is to show $|Y_i-B_0-B_1X_{i}-B_2X_{i}^2 |$ has more than one min value. We are given $x_1=1$, $x_2=2$, $y_1=3$ and $y_2=4$. I am truly lost, I need to show there are more than ...
13 views

### Non-parametric variogram estimators

I'm working with overdispersed, count spatial data. The goal is to look specifically at spatial dependence patterns. I'm trying to fit variogram models to empirical variograms, however the only ...
15 views

### Pooled and Fixed Effects Results

I use a hausman test to determine whether pooled ols or fixed effects should be used and the results favor fixed effects estimation. But when I estimate fixed effects the results of my main variable ...
57 views

### Constructing alternate hypothesis: How to determine if Ha > H0 or Ha < H0

In Chapter 8, Test of Hypotheses based on a Single Sample, in Devore's Probability & Statistics for Engineering and Sciences, he states that the null hypothesis, $H_{0}$, is the a priori claim ...
44 views

### Meaning of the Boosting algorithm for Regression Trees

I have a problem with understanding the concept of the Boosting Algorithm. ...
3 views

### What are good tutorial on Weighted Finite Automata?

I would especially appreciate papers, books or tutorials with source code already available. Currently I'm reading "Spectral Learning Techniques for Weighted Automata, Transducers, and Grammars" by ...
13 views

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18 views

### Inconsistent Performance of PCA Results from SPSS

I've completed PCA with my dataset (16 variables) and extracted 3 factors. I then created an Excel spreadsheet where I can enter in user provided data and calculate the scores for each of the three ...
20 views

### Hidden markov model multivariate regression with time-series data

I am working with a dataset that includes the trajectories of various car trips and would like to be able to predict their destinations using only a subset of the trip trajectory. For instance, if in ...
9 views

### R: how does caret choose default tuning range? [migrated]

When using R caret to compare multiple models on the same data set, caret is smart enough to ...
38 views

### Hazard function, survival function, and retention rate

What is the difference between the hazard function, survival function, and retention rate in survival analysis?
15 views

### Plotting List of Words with R [on hold]

I am an R beginner in way over his head. I am starting with a list of character vectors. It starts with 25 words. Each year some of these words are pruned from the vectors. I want to plot the list of ...
16 views

### Using MCMC to simulate complex process from given parameters [on hold]

Assume I have a complex Markov stochastic process (think a soccer model), where the scoring intensities change during the match in ways, depending on various parameters. I have it implemented as a ...
27 views

### Merge 3 distribution into one distribution [on hold]

It is possible to merge 3 distribution into one.. I was thinking of something as seeing how much they correlated each other and based on that, come with an $\mu$ and $\sigma$ defining the merged ...
15 views

### Finding conditional distribution in graphical model (undirected graph)

Given that I have a graph $G=(V,E)$ and a set of random variables $X:=(X_v: v\in V)$. I also have the joint distribution of $X\sim p(x)$. What are the ways to find out the conditional distribution of ...
41 views

### k means with binary variables

Is it OK to use kmeans with binary variables? I mean Euclidean distance? I guess the binary variables will be the ones that get the most power to determine the ...
63 views

### Intuitive explanation for when Pearson correlation coefficient equals 1

Whenever I teach a complicated formula, I always demonstrate to the class that it works intuitively in extreme cases. For example, when all the data values are equal, the standard deviation is 0. Not ...
7 views

### Baye's Classifier problem [on hold]

Here's the problem set: I got the first two sections down but I have no idea how to do the third section. Can anyone help?
26 views

### Why do thse two methods yield the same estiamte [with code]?

I am running the following (in R): ...
10 views

### Factorization Theorem for sufficient statistics

I have a question on factorization theorem for sufficient statistics. I understand that to state whether or not a sufficient is statistic, you must factor the likelihood function of the pdf into two ...
10 views

### On the use of the autocovariance generating function

The autocovariance generating function is defined as: $$g_X(z) = \sum_{h = -\infty}^{\infty} \gamma(h)z^h.$$ Where $\gamma(h)$ is the autocovariance function of the considered process $X$. I can ...
13 views

### Interpreting conflicting hypothesis results from anova test

I've created a test where a participant plays a game and must maneuver as many 3 pointed stars to the right side of the screen and 4 pointed stars on the left as they can within a time limit. The test ...