# All Questions

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### Ambiguity of Chi-Square test of association

Recently I have been struggling with the following two issues of Chi-Square test of independence/association during reading an article. First question: Does chi-square test able to dectect no ...
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### Creating a mixed model for repeated measure using lme function (library(nlme) in R)

I have a question about a selection of the most proper model and subsequent ANOVA for my experimental data. I have one response variable - Net assimilation (Anet). Then I have 5 categorical variables ...
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### Creating a personnalized PCA (not using variance as optimization criteria)

I have a simple question (I hope I can explain it clear enough). I want to train and apply a PCA to a set of data (I want to have an orthogonal basis in a low dimension subspace with unitary ...
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### media classification open-source software

I'm working on a multimedia/cinema project involving the classification of different kinds of media (primarily video but also audio and text) into a single database which needs to be queried. I intend ...
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### Suggestions on statistical models

I have 6 independent categorical variables (x) and one dependent variable (time) y. What are some appropriate statistical modeling techniques if my objective is to predict time (continuous variables) ...
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### Repeated measure, t-test on the sums?

I need some help to find a suitable hypothesis testing solution... To make my problem clear, I give you and example. Imagine my hypothesis is that firms in City A are more profitable than firms in ...
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### Logistic Regression vs ANOVA for categorical variables

In a problem that I have to predict a categorical variable (0/1) using a set of categorical variables, does it make any difference in prediction accuracy whether I use a logistic regression or ANOVA? ...
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### How to conduct a three way ANOVA with non-normal and heteroscedastic data?

I am currently trying to analyze a data set to check the effect of three factors (year, plant, water stress) on yield. But the distribution of my data is not normal. I tried several transformations ...
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### Quantile Regression: follow up methods to have a more fine-grained understanding of what the results really mean?

I recently employed multiple quantile regression in my area of research and found some interesting quantile differences across the distribution of Y, but I don't quite understand what they all really ...
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### Decision Trees rpart R categorical and continuous variables

I run some decision trees in rpart with 10 continuous variables and 3 categorical variables (with 1 or 0 options), the result of the tree was that none of the 3 ...
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### Quantile regression with continuous endogenous variables

First of all, let me apologise if this question has been resolved elsewhere on the site / the net. I have been researching a methodology for IV Quantile regression with continuous endogenous ...
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### When to stop agglomerative hierarchical clustering - stopping criteria [on hold]

I am coding my application each function so i am not using tools which does everything for you Been looking for solution when to cut my agglomerative hierarchical clustering How do i cluster? I ...
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### Comparing the within-subject variance between two groups of subjects

If each subject has repeated a test multiple times, I am able to compute the mean and variance of their performance. (I am assuming the results to be normally distributed). 1) If it is the variance ...
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### Random coefficients in regression

Can I use the random coefficients extracted from a random coefficient growth model as predictors in a regression analysis? If the random coefficient growth model also contains a second-order ...
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### Quantifying the error from a Bayesian model

I have a Bayesian model that predicts the chance of some event occurring. To view the accuracy, I took the prediction output of my test data and binned it every 10%. For example, if the model ...
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### Coefficient in differences-in-differences regression significant for log-level specification but not for level level

I am estimating a differences in differences model: $Y_{it} = \alpha_i + \beta_t + \tau T_iP_t + \epsilon_{it}$ where $\alpha_i$ and $\beta_t$ are fixed effects, $T_i$ is a dummy variable indicating ...
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### Interpreting steep histogram, fitting distribution

I'm trying to fit the distribution to the data. I started with histogram. Note that y axis is in logarithmic scale since the histogram is very steep. How should proceed to find actual ...
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### Hypothesis testing for inaccurate sampling

My problem is as follows: Imagine a set of points, their positions have been recorded with a rubbish GPS, so are not precise and have a high error (assume no systematic error). Call this set $I$ ...
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### Confidence band for mean of means

This is sort of a stats theory question, and I can't really convince myself of the correct way to view things: In normal regression, the confidence band (or interval) gives the bounds on the mean, ...
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### Variable Selection Method for Multinominal Model

When dependent variable is categorical (more than 2 categories) and independent variable is continuous, is there any way i can check the predictive power of independent variable? Can i apply one-way ...