# All Questions

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### ratio of standard errors

Is there a general interpretation of the ratio of two standard errors, $\frac{se\left(\hat{\theta_1}\right)}{se\left(\hat{\theta_2}\right)}$ We want the standard error to be as small as possible so ...
4 views

### Find distribution of underling feature

Let's say I have a dataset compose of value for the variable W. The distribution of W doesn't follow any obvious know distribution. I have a model that gives W as a functions of E and K. W = f(E, K). ...
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### Concept learning

Assume you are considering an instance space of 6 binary and 1 nominal (with 3 possible values, like Rainy/Sunny/Snowy) attributes. What is the total size of this instance space X with these 7 ...
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### In triple exponential smoothing, what is the proper formula for recalculating gamma (seasonality)?

A pretty targeted but precise question -- In triple exponential smoothing (which there are many combinations of additive, multiplicative). What is the proper formula for calculating the new ...
10 views

### Calculating Log-Likelihood from Simulated Distribution

I want to perform some sort of model evaluation of a multivariate distribution with the property that it is difficult/impossible to calculate the likelihood (of the whole model, you can do it for ...
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### How to explain change of sign on regression coefficient when another variable is added to OLS model? [duplicate]

I am trying to run an OLS regression, with log of per capita calorie as my dependent variable and age and years of education of household head, log per capita expenditure as my independent variables ...
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### Repeated measures or two-way ANOVA, and power analysis

A sample of patients will undergo two treatments. Every patient will receive both treatments.One treatment will on the left side and the other different treatment on the right side. Repeated ...
13 views

### Algorithm for uniform sampling with bounded replacement

Is there a simple algorithm to sample from the uniform distribution on sequences of $n$ numbers, each taking one of $m$ integer values from $0$ to $m-1$, where each value can be repeated at most $r$ ...
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### Density plot of parameter estimates from linear regression model

I am running a linear regression model in R: data(iris) fit1.iris = lm(Sepal.Length ~ Petal.Length+Petal.Width , data=iris) summary(fit1.iris) These are my ...
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### Mean field variational inference

In Chris Bishop PRML book p.465 equation 10.6, the derivation doesn't explain why exactly the term $\int q_j ln(q_j) dz_j$ was generated, is not that term supposed to be multiplied by constant, did ...
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### Is this logit model a multilevel model, and what is the correct way to model it?

I am analyzing a sample of about 6000 actions carried out by about 500 multinational companies in about 80 countries during a 6 year period. Actions are carried out randomly, and are not longitudinal ...
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### Need to know if this is right and how to calculate this.\

I need to stat the null which I think is H0: P=124 Ha: P≠124 am I on the right track? I also have to test at a 5% significance level and show appropriate test stat a P-value. The stuff we went over ...
12 views

### Anomaly detection: multivariate Gaussian distribution

I am trying to do anomaly detection on a heterogeneous dataset (There are unknown groups present in the dataset). I want to try multivariate Gaussian distribution based approach, but I was thinking of ...
14 views

### Overestimating variance with MCMC

I'm working with a very specific type of proposal distribution in MCMC algorithm. To validate it I use a simple multivariave Gaussian with $\mu=0$ and $\Sigma$ an identity matrix. The proposal ...
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### Self-study: Finding the maximum likelihood estimates of the parameters of a density function

Consider a random sample $x_1,x_2,...,x_n$ from a newly-generated distribution, whose probability density function is given below f(x|\alpha,\beta,\sigma)=\frac{1}{\Gamma \left( ...
19 views

### Interpreting negative binomial regression with log transformed independent variables

My dependent variables were highly skewed, so to normalise the distribution they were log transformed. Also since there were zeros in the data, I've added + 1 to transform the variables. This is what ...
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### Understanding multiple KS tests

I have read these two questions Why are p-values uniformly distributed under the null hypothesis? and Understanding scipy Kolmogorov-Smirnov test And this inspired me the following experiment. I ...
2 views

### Is smooth.spline appropriate for presenting the trend of chemical concentration in a catchment

In my case,the Electrical Conductivity (EC) values are measured daily in some pints of catchment from 2007 to 2014, and around 20% data are missed, due to without probe or flux. To presenting the ...
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### Dependent samples but unable to pair individual scores

We surveyed a group of students before an in-school year-long project and after, and want to see if the changes in scores are significant. Data doesn't meet assumptions of normality. Can we use the ...
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### How to check that the selected features are not overfitting

I'm trying to select best features for sentiment classification for a set of reviews, and using penalized SVM and Logistic regression to perform such task. by basically iterating over different ...
113 views

### Curious distribution

While checking my Android App Rating I saw this It's almost a quadratic progression! Is there any explanation for such a rating?
39 views

### Is stratified meta-analysis more or less objective than meta-regression?

Reviewer asked me why I use meta-regression as a way how to deal with heterogeneity among effect sizes instead of conducting stratified meta-analysis. I tried to google "stratified meta-analysis" and ...
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### Maximum Entropy classifier, high precision but low recall

I'm working on a sentiment analysis study of twitter data using the Maximum Entropy classifier. I've gathered dozens of thousands of tweets. To produce features, I used unigram, bigram and dictionary. ...
41 views

### Hourly predictions using time series

I'd like to build a model based on time series. I have a dataset with records every 30 minutes for three months. What is the difference between modeling these data with the following kinds of ...
22 views

### Finding maximum likelihood estimates of parameters of multiple normal populations

I've just started studying maximum likelihood and likelihood ratio tests. I've calculated the maximum likelihood of a normal population with unknown mean and variance. However, I've been given this ...
25 views

### A reference for Pearson's chi-squared testing

I am wondering if there is a reference for the Pearson's chi-squared test suitable for technically-sophisticated audience that simply presents when the test (in its various forms) is appropriate and ...