# All Questions

11 views

### How to Analyze Likert Scale Data Using Statistical Tools?

I'm doing an MBA dissertation on the topic "Impact of Customer Service Satisfaction on Business Performance". The hypothesis set is "Customer service satisfaction can positively impact business ...
15 views

### Is it valid to reduce the AICc penalty for multiple variables, when some variables should be grouped?

I have a data set of mean trait values for each of 18 populations, and want to test whether several ecological variables are related to variation in traits. I'm using the corrected Akaike information ...
5 views

### How to do SVAR for oil shocks (Killian) in Eviews [on hold]

anyone have a step by step to run SVAR in eviews, especially related to Killian's oil price shocks. I am confused about what to do next after the Unit root test. Thanks
24 views

### Difference between Granger Causality and AR1

Here are my questions: is there a difference between "VAR(1)" and "AR(1)"? Granger Causality inspects the direction of causality. In return, we receive a p-value on how much a time series is likely ...
17 views

### A linear learner has high bias, because when the frontier between two classes is not a hyperplane the learner is unable to induce it

Can someone explain to me what this sentence means: A linear learner has high bias, because when the frontier between two classes is not a hyperplane the learner is unable to induce it. The ...
4 views

### “not sorted” error in Xttest0 in stata [on hold]

I have panel data and doing analysis in Stata 13. So when I run xttest0 to check for random effects I found an error "not sorted". Please help me what this error mean and how can I resolve this ...
385 views

### Hypothesis testing. Why center the sampling distribution on H0?

A p-value is the probability to obtain a statistic that is at least as extreme as the one observed in the sample data when assuming that the null-hypothesis ($H_0$) is true. Graphically this ...
11 views

### Estimating data set size for pattern extraction

I have a dependency treebank including 100 structures, which I divide into training set and test set. I extract some rules ((DS,PS) pairs) to convert the treebank to phrase structures. When I extract ...
5 views

### Tuning hyperparameters in light of a very large dataset

I have a rather large dataset (1M training samples). Each epoch in my neural network takes about 12 hours. I'm wondering what is the best strategy to tune the hyperparameters (batch size, step size, ...
12 views

### AUC seems too high, confusion matrix seems only slightly better than random

My confusion matrix looks as follows: > table(actual, predicted_all) predicted_all actual 0 1 0 1728 5261 1 2088 168 While the AUC ...
20 views

### Identifying statistically significant categorical variables with rma.mv

I'm running a meta-regression/multi-level analysis that contains only categorical variables. The printout of the data is as follows: res.fe ...
49 views

### Random forest and LASSO regression both give different variable importances

I have a dataset with 163 observations (all countries in the world with population > 1000000) and 290 variables related to their disease burden and performance. Because there are more variables than ...
2 views

### Randomly delete/replacing X% of the data using R (or other tool) [migrated]

I am quite new to R other statistical tools. In order to measure the performance of an imputation technique, I want to randomly delete or replacing X% of the data so I can compare it with the original ...
9 views

### Correlation based feature selection(CFS) tool

Is there any tool or script that was implemented for correlation based feature selection? My feature vector data is in a large-scaled data file, so if I use tools like Weka for feature selection, I ...
18 views

### Why do loadings of princomp in R report identical proportion of variance for all principal components? [duplicate]

I'm trying to run a few tests using princomp in R. In princomp there is a value called <...
13 views

### How can I have more factors than there are variables

I've come to learn about factor analysis as mainly a dimensionality reduction tool. However, can we also use the factor analysis method to have more factors than there are variables? If so, what would ...
3 views

### How does hashing by non-linear table look-up work? [on hold]

I am trying to grasp the concept of Hashing by non-linear table look-up but cannot understand how to formulate such a hash function. https://en.wikipedia.org/wiki/Dyadic_transformation shows a non-...
25 views

### Implementation of PCA using SVD without creating covariance matrix

So I'm currently taking a Machine Learning course and have correctly submitted my implementation of PCA. I used SVD. Here it is Octave. ...
35 views

### Continuous uniform random variables convergence question

Let $X_1, X_2, \ldots$ be independent $U(0,2)$ random variables and let $$Y_n = \prod_{i=1}^n \, X_i \;.$$ How do I prove or disprove that that $Y_n$ converges to $0$ almost surely ?
6 views

### Can two stage cluster sampling have clusters of size zero?

Can a cluster size be zero in cluster sampling? Say in a two stage cluster sampling, one has unequal cluster sizes with some zero-sized clusters, which means no items will be sampled from the zero-...
19 views

### Handling the “positive bias” in percentages of positive variables

Say we run an experiment and notice the following impact on a variable of interest (one row per experimental unit): ...
4 views

### How to calculate multi-class prediction probabilities using One vs All and One vs One classifiers

To be specific, let's consider Support Vector Machines. In the 1 vs all case, one has $n$ binary classifiers where $n$ is the number of classes. In each classifier one has two labels 0, 1 and for a ...
39 views

### Is real analysis necessary for statisticians? [on hold]

I'm almost finishing the undergraduate course in Statistics. Is it worth take a course in Real Analysis if I don't intend to do the master's degree? This will help me in something in the labor market ?...
13 views

### How to learn machine learning techniques on thermal model like Nest does?

I am trying to build some smart home devices by myself. And I am very interested in build some kind of algorithm like Nest Thermostat does which is able to learn the characteristics of the house and ...
22 views

### How do I find the standard error of the estimate when using S estimation?

How do I find the standard error of the estimate when using S estimation? ...
13 views
+50

### Average Marginal Effects from Chamberlain-Mundlak Device CRE Probit

I am trying to calculate the average marginal effects for the Chamberlain-Mundlak Correlated Random Effects probit model. The ultimate goal is to get something equivalent to the AME from the fixed ...
20 views

### Is my survey invalid now?

I'm running an online survey for my thesis. In order for the survey to be valid, I needed a minimum of 375 participants. And I have achieved this number. However, upon closer inspection I have ...
12 views

### setting log-uniform priors in Stan

I have been using Stan for a couple months now and I want to adopt a log-uniform prior on some parameter array real theta[N]. I want to do something like a ...
7 views

### Document Length Normalization

What is the difference between document length (total no of words in the document) normalization and cosine normalization? How do we usually normalize a document represented as a set of words and ...
5 views

### doubt on ADF unit root test [on hold]

In ADF test, how to select the lags if i have 22 observations(annual data)? which criteria i have to use AIC or BIC or t statistic? if i get the p value is less than 0.05 in levels by increasing the ...
72 views

### Permutations and probabilities for indistinguishable balls into indistinguishable fixed-sized buckets

I'm neither a statistician nor a mathematician so apologies if this question is asked and answered elsewhere or if I've misdescribed my problem. I am trying to figure out in a thread in stackoverflow ...
27 views

### Equivalent of standard error for variance?

I would like to know if there is an equivalent formula of standard error for variance or standard deviation, that is, I would like to know how far the variance of my sample is from the real variance ...
9 views

### Accounting for Team Size on Clique Cohesion?

So, right now, I'm trying to model cohesion for different size team. Imagine, we're talking about in-person social interactions. Every person is divided into different teams. I'm interested in how ...
24 views

### What's the difference between univariate and multivariate cox regression?

I'm dealing with oncology patients so it would be nice to know whether to use univariate or multivariate cox regression. I have some books on survival analysis but they don't elaborate the academic ...
31 views

### How would a bayesian and a frequentist answer this question? [on hold]

I have a site which which in which there are lets say 1000 visitors every month and out of 1000, 10 people actually sign up on my site which leads to a 1% conversion rate. Now I invest in the ...
20 views

### GGPLOT2: barplot issues with categorical variable [on hold]

Good Afternoon, I am having trouble figuring out how to get ggplot to plot this the way I am envisioning it. I am quite new to R, so I am still learning. Here are two examples, the first, I would ...
2 views

### Difference between skeleton and medial axis [on hold]

Guys I'm having serious troubles of finding the differences between a skeleton of a 2D object and a medial axis of a 2D model. Wherever I look it comes up that they are the same . But I think they are ...
38 views

### What is Statistics? [on hold]

I suggest to pause for a moment, sit back and think about this philosophical question. What are we doing when we are doing statistics? How to embed statistics into the landscape of modern science and ...
15 views

### Estimating error from scaling transformation onto a theoretical graph

I have a numerically calculated graph, on unit-less coordinates. I have experimental data which corresponds to a point on that graph. The data has units, and to make it unitless one has to divide it ...
20 views

I found that after running a CFA, positive factor loadings and negative factor loadings occurred as appropriate. (An item representing a high score and an item representing a low score on the same ...
6 views

### Bayes factors and ROC curves

The question comes from Kevin Murphy's book, Ch 5, Ex 5.6. Could somebody suggest a solution? Let $B=p(D|H_1)/p(D|H_0)$ be the bayes factor in favor of model 1. Suppose we plot two ROC curves, one ...
34 views

### Removing undefined (NaN) values during log-likelihood maximization

I am trying to maximize a Poisson likelihood function for an array of values, of the form llhij = -mij + kij*ln(mij/kij). (where I use the numerical approximation ln(k!) ~ k*ln(k)). For my ...
34 views

### How to prove the reliability of a predictive model to executives?

I trained data from 500 devices to predict their performance. Then I applied my trained model to a test data set for another 500 devices and show pretty good prediction results. Now my executives want ...
12 views

### What's the difference between t-test and sequential F-test?

I just started learning linear regression, and I couldn't completely understand the difference. I know the t-test is testing NH:$\beta_i = 0$ and AH: $\beta_i \neq 0$. The overall F-test is testing ...
20 views

### Consequences of overlap between training, validation and test data

If I'm splitting my data in training, validation and test data to assess different (sub)sets of features for my task. What are the consequences if I (by mistake) split my data incorrectly? In the ...
18 views

### What do attendance figures tell me about regularity? What does the average tell me about individual attendance?

Suppose I have a group of $N$ people, attending a series of $M$ events, and (for simplicity) let's assume the overall attendance happens to be the same at each event, say $A$ people (ranging between 1 ...
If I have 2 random variables $A$ and $B$, with unknown means (denoted $\mu_A$ and $\mu_B$), and I want to estimate $\mu_A/\mu_B^2$ from $n$ samples of each, $\frac{\sum A_i/n}{(\sum B_i/n)^2}$ is ...