# All Questions

171 views

### Interpreting 95%CIs - why perform formal statistical tests or multiple comparisons?

95% (or other %) confidence intervals indicate the range in which we expect the true mean to lie with 95% probability (= 'confidence') according to the Central Limit Theorem, given the precision of ...
3k views

### How is the Weighted Gini Criterion defined?

I am interested in trying out and/or implementing the Weighted Random Forest (WRF) algorithm described in Chen, Liaw, Breiman. How is the Weighted Gini impurity actually defined? What implementations ...
4k views

### (Multiple) Correspondence Analysis for count data entered as binary variables

I have a data set, 1014 cases and 55 variables which are binary and is in the form of ...
108 views

160 views

### Expected value calculation

I have great difficulty in calculating $\mathrm{E}\left(\sqrt{T_{1} T_{2}}\right)$ where $T_{i}$ is a random variable distributed according to the Birnbaum-Saunders distribution. Are there any ...
930 views

### Can someone give a simple guide of Dirichlet process clustering?

I am trying to understand the Dirichlet process and Dirichlet process clustering, but because of my lack of knowledge of stochastic process theory and measure theory, I cannot understand what the ...
127 views

### Significance of adjacency in correlation matrix with ordered variables

The following values are from the Discrete module in BayesTraits. Each value in the matrix is the difference in log-likelihood values between a 4-parameter model of independent evolution and an ...
45 views

### Girsanov Theorem

I am interested in understanding Kallenberg's Proof of Girsanov's theorem. The Theorem says: If $Q=Z_{t}P$ and $Q$,$P$ are probability measures and $Z$ is a.s. continuous, then for all local ...
364 views

### Fit VAR model with unknown order in Matlab

I have a multivariate observed time series $Y_t$ and I want to find the best fitting VAR process for it. I have the econometric toolbox in Matlab and can use 'vgxvarx' if I pre-specify an order for ...
732 views

### K-means clustering for usage profiling

I am trying to use k-means clustering to profile mobile device usage behaviour for IT users. My data consists of different system and user level variable/readings like number of calls/sms, cpu/memory ...
50 views

### Unbalanced repeated measures

I'm new to using R and therefore I have some doubts. I have a data table with measures gland secretion of chickens at two ages different, sometimes we just need a measure therefore is not balanced. ...
638 views

### Performing multiple comparisons on linear mixed model

I have collected data on gas fluxes from plots of soil subjected to 5 different treatments ("D2", "K2", "M", "N", and "O2"), which also possessed variable clay contents. The experiment was laid out in ...
122 views

### A concise way to describe the distribution of words in a text

I have a text, and I count, for each distinct word, the number of times that word appears in the text. In some texts, there are many rare words, so the distribution will have a long "tail" of words ...
154 views

### Which statistic to prove that one data point dominates the proportions in dataset?

I'm very new to statistics so apologies if this is a dumb question. I've got a grasp of the concepts but not real-life usage of them (but I am learning!). I have a skewed distribution where one ...
224 views

2k views

### auto.arima and prediction

I'm really new to ARIMA methods and am trying to forecast electricity load. I've integrated: electricity load, temperature, weekday (dummy), public holidays, and school holidays. My model tries to ...
2k views

### Conditional vs unconditional expectation

I'm having trouble understanding the calculation of conditional versus unconditional expectations in this case: \begin{array}{c c c c} & \quad &X=1\quad &X=-1\quad &X=2 \\ ...
199 views

### Plotting fit for binomial lme

I've been asked by a reviewer on a manuscript to provide plots of a model fit for a binomial lme which is specified as follows: ...
2k views

### How to calculate the Bayesian posterior probability from observations?

Let's say I give you a 10-sided die and tell you that it is biased in some way. I then let you roll the die 5 times and you observe, let's say, 8, 8, 8, 2, and 8. Lastly, I ask you what your belief is ...
138 views

### Predicting for month in R

I'm trying to understand some concepts related to predictive modeling. So let's say that I have the following data sample and am trying to regress sales on ...
1k views

### Stochastic inequality with product of binomial distributions

I am interested in modeling the following experiment: A binomial trial with $n$ Bernoulli experiments is run. For the k positive outcomes a second (independent) binomial trial with $k$ runs with a ...
107 views

### Can we never have a normal distribution?

Since the population variance can never be estimated, will we always have a t-distribution instead of normal?