# All Questions

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### Paired t-test of a non-normal data with sample size 66

I have a paired data with n=66. I understand that normality condition of differences data should be met to conduct a paired t-test. However, from the histogram, it doesn't appear so normal. The p-...
4 views

### Creating personalized demogdata from demography package [on hold]

I'm trying to create my own demogdata and can't get around my error message. My command is ...
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### Unbalanced dataset accuracy

I’m currently encountering some problems analyzing a dataset with neural network. The problem is that I have an unbalanced binary class training set (10:1). Training accuracy for both classes are 100%....
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### Which test should I use to determine a relationship between Social media activity and calls booked from activity?

We run a business and I am trying to calculate the worth of spending time on our social media groups to book calls with potential clients. I have a list of social media activity for the last 60 days (...
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### sufficient subsample size for given sample to obtain same regression

I am performing an engineering analysis to find out the effect of earthquake on concrete buildings. Analysis applies earthquake forces on building model for 50 earthquakes, resulting into separate 50 ...
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### Problemes to fit a model for variogram

I am having problems to fit a variogram model, I tried to change some parameters to estimate or fix them but still not archiving any improvement. I remove trend of the data and use logaritm because ...
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### how i found elements in every cluster in python

In python i did cluster. I have a table with 26000 cloth's article and 52 weeks. The values in the table are the sold quantity of every article during the weeks. I'm doing clustering of time series.....
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### VIF Drops Significantly When I Delete Some Dummy Variables

I have a a category variable (Fruit) that I converted to dummy variables: columns Apple, ...
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### Why does this standard deviation go outside the bounds of the sample?

Not a stats major here. The Rand Corporation recently released a study on the US Army's junior enlisted ranks. Here's an excerpt from Table A.1: ...
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### Bitcoin value time-series. Third-order difference or consider direction of value change?

I am conducting a study on the value of Bitcoin in the period between July 7th 2018 and October 8th 2018. My independent variables are number of discussion and sentiment of discussion about Bitcoin on ...
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### Adding positivity constraint to GP

I am fitting a simple one-dimensional GP model to my observations. My observations are simply the mean number of people/minute who visited a store between different time intervals. So, my data looks ...
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### Sampling Problem

Solution Please: Following are the no. of stores in 10 cities: 35, 27, 24, 32, 42, 30, 34, 40, 28, 38. If we want to select a sample of 15 stores, using cities as clusters and selecting within ...
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### Designing an individual survey to capture team details

I'm wondering what the best strategy is for collecting the following data. Let's say individuals have signed up to do some kind of task, and they can sign up either by themselves or with a variable ...
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### How to interpret contrasting information from the Variation of Information, Dunn and Rand Index for comparing clusterings

There are related questions but the answers don't seem to explain how to practically judge these measurements for non stats users. I have a dataset which I clustered with K=4 using hierarchical ...
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### Analyze time series (with python) to forecast future and to get trend

I'm analyzing a time series that has this format: ...
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### Usage of Heckman estimation for a random sample

My colleague argues to use a Heckman Model in the following case (Agricultural economics): I have a random sample of farmers (n) of the general population N. In n some observations apply a given ...
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### “exotic” weight regularization?

In neural nets, there is often a weight regularization term in the loss function, which ensures that unnecessarily high weights don't occur. For example, if $C(\theta,x)$ is the baseline loss function,...
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### Are the estimates of a binary proportion and of its complement considered 'simultaneous'?

Consider the inference '60% events +/- 3%' from a random sample of a binary frame. The complement is '40% non-events +/- 3%. If expressed together (i.e. '60% events AND 40% non-events), would the ...
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### Searching for a rhythm in weight loss/gain

Asking for a fiend, who has read this. Basically my friend weighs daily and has historical data in CSV format. They would like to take that data and overlay it in some form of weekly chart. E.g shows ...
10 views

### How to evaluate performance of (variational) autoencoders?

Let's assume that you have trained your (variational) autoencoder on MNIST digits. After some time, you check the result and decide that the reconstruction is pretty good. But this is highly ...
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### Simple Random sampling with replacement - Variance

If just a single unit is drawn at random from the whole population and y1 is the value of y for this sampled unit, how can I prove that the VAR(y1)=by (1 − 1/N)σ^2 (where N is the population size and ...
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### How to estimate Breslow type Baseline Hazard for mixture cure model?

I have done the following bit myself: ...
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### Inverting Hessian using Generalized Inverse for Inference

I am estimating a survival model with MLE. I use optim to maximize the likelihood function, and I intend to use the Hessian matrix returned by optim to get the standard errors (which lie on the ...
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### Is it possible under this design that any given population unit may be selected more than once? [on hold]

The simple random sampling design considered should more precisely be called simple random sampling without replacement, because it is not possible to select the same population unit more than once. A ...
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### Ranking based on number & production of referrals

I have a list of approximately 250 referrers that I need a better ranking system for. I have tried ranking strictly by productivity of referrals however that often results in a ‘one off’ doctor being ...
14 views

### Poor Performance of the combination of a regression method and Kriging

Is it common that the combination of a regression method and Kriging is performing worse than the regression technique alone? I tested the combination of support-vector machine (non-linear kernel), ...
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### Cross framework serialization and desrializatioin of ml models [migrated]

I am new to ML and as Data Engineer was wondering how the general process of moving ML models to production works. Taking into account fact that many of models are prototyped in notebooks usually with ...
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### Fundamental principles of the central limit thorem [duplicate]

I've got a semester project about statistical methods. One of the questions we have to discuss is the fundametal priniples of the central limit theorem. Is there someone that can help me with ...
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### MatchIt: Explanation of Missing Factors from Summary

I am using the MatchIt package to perform matching between two groups (obese and not obese). The dataset that I am using has no missing data. I am matching on age, sex, and race. Sex and race are ...
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### Average of some percent numbers [on hold]

For a scientific purpose, I want to analyze the function calls of a software program. The analyzer reports for what reason the function call had been stalled during the execution. For example, the ...
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### Optimal Sample Size/Power Analysis for Panel Data

I'm running a economic experiment. From a previous pilot I already know which size of treatment-effect I can expect. Each participant plays 20 rounds, so it't a repeated measures approach. I want to ...
8 views

### coefficient of variation with different (n) [on hold]

variation measurement with different sample size
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### Legend not showing for manually drawn line [on hold]

Folks, I cannot get the legend to show up for the manually drawn line (on the second line of the below code). Any suggestions on what is wrong? Thanks. ...
21 views

### Atoms of a sigma algebra

I've been reading Schilling's Measures, Integrals, and Martingales, and I ran across a remark (on page 21) that I don't understand. Here is the setup: let $A_{1},\ldots,A_{n}$ be non-empty, ...