# All Questions

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4 views

### Determining sample size for chi squared

I'm currently writing a project proposal in which i've been told i need to estimate the sample size i require. Im planning to look at the effect of culture time (split into three groups) on IVF ...
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### How to know how did voters changed their mind since last elections through linear regression?

I have a dataset of precincts and results of parties on different elections (let's focus on two : 2008). After reading this article I really wanted to use linear regression to answer the question : ...
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### Conditional heteroscedasticity for the tobit model in Layman's terms

I have been using the crch package for modelling censored data with the tobit model. I noticed early on that the errors (by far) are not normally distributed by ...
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### Does negative Z score in Cochran-Armitage test implies the presence of an increasing trend?

Given the p-value is less than 0.05 does negative Z score in two-sided Cochran-Armitage test implies the presence of an increasing trend?
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### Croston's Method (forecast)

I ran Croston's Method on this data(Sales) with h=3 ...
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### how to choose the number of patches in sub-region classification before appling CNN?

I'm currently working on image classification, i want to divide the input image into sub-regions(patches) and apply a deep convolutional neural network (CNN) to train and classify each patch ...
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### Sensitivity analysis of an equation in R language

I have the equation, Y = A*B*C/(D*E) Where A, B, C, D and E are the certain parameters of 1000 samples (say groundwater samples). ...
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### How can I accomodate the forecast series to separately fit and predict workdays and weekends?

I'm using the forecast R package. I have the same dilemma as How to forecast daily time series with weekends and holidays?. I understand that the answers consensus ...
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### Hard time understanding the parameters of a prediction interval

I stumpled upon the definition of a prediction interval from https://www.statisticshowto.datasciencecentral.com/prediction-interval/ In my setup I have a type of tree-based regression model with non-...
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### Finding joint distribution of sum of independent Poisson random variables and calculating probabilities

My textbook, Introduction to Probability, by Blitzstein and Hwang, provides the following problem: Let $X = V + W$ and $Y = V + Z$ where $V$, $W$, and $Z$ are independent $\text{Pois}(\lambda)$ ...
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### Asymptotic distribution of intraclass correlation

Consider the random effects ANOVA model below (notation based on Snijders and Bosker, 1999), where $j$ represents a group and $i$ an individual:  Y_{ij} = \mu + U_j + R_{ij}, \qquad var(Y_{ij}) = \...
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### Clustering using histograms

I need to find clusters in a very large amount of data (>2M data points), and I was looking for ways to speed up the usual algorithms, i.e. k-Means, DBSCAN, ... Is there any major issue, especially ...
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### Finding the maximum and minimum variance of the sum of two Bernoulli events?

You are guessing the contents of two envelopes. Let Ui be the event that you guess correctly. Your probability of guessing correctly for each envelope is P(U1) = P(U2) = 3/4. U1 and U2 may or may not ...
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### SPSS and Linear Mixed Models

I hope you would be able to help me! I am working on a LMM in SPSS right now and I've gotten to the point where I don't really know what to do. I am looking into comfort (so that is my DV, measured ...
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### How can I calculate principal components scores in a compositional data PCA?

I hope someone can help. Please let me know if my question is not clear. I have compositional data, where there are three variables which sum to 100% for each row, something like this: ...
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### Statistical test for testing if test set is sampled from same domain as training using occurence of certain features

I have text samples pre-split in training / test for binary sentiment classification. I have a suspicion that the test set was sampled from a different domain than the training set. There are several ...
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### Is having too many comparisons a valid reason to increase FDR threshold level?

To briefly summarize, I have a bootstrapped data set that needs to be corrected for multiple comparisons. The figure below provides a snapshot of one set of the data. The x-axis is in bins of 60ms. ...
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### Subtract column values in python [on hold]

I have columns 'Longitude', 'Lattitude' and 'Battery' in my dataframe. I want to define a function if the difference between alternate battery value is more than a threshold, it should return 2 ...
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### R hypothesis testing (non parametric)

Working with the Golub dataset, I am attempting to use the Wilcoxon two-sample test to find the genes that have a higher mean expression value in the AML group as compared to the ALL group. What is ...
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### ARIMA forecast for upcoming 2 days

I am trying to forecast the battery charge for the next 2 days. I have data for 3 days with 5 mins interval. I have tried the below code: import statsmodels.api as sm arima_mod = sm.tsa.ARIMA(...
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### about PMI(pointwise mutual information) independence

as picture shows it says A, B are independent which means P(A,B) = P(A)P(B). then isn't pmi always 0? because log1 = 0? what am i assuming wrong here?
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### What are the odds [duplicate]

What are the odds Ive met my other half? Thing is I already know I have with this undeniable experience we had when our souls actually collided together as we were one. I just want to know what ...
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### Regression with ranked and truncated dependent variable

I'm struggling to find a model that will best fit this data. The dependent variable is the ranking of a observation based on how many votes it received based of a list of choices (number of votes is ...
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### How to partition a correlation matrix into two extreme groups?

I have a correlation matrix of 40 random variables: $C_{ij}$, $1 \leq i,j \leq 40$ I want to partition the 40 variables into two groups (of 20 each) such that the average correlation differs by most ...
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### Measuring variation explained in community matrix using both geographic distance and and environmental variables

So I have this dataset where I have species community data from a variety of sites. I’m trying to explain what are the factors that drive the variation in these data. For each site, I have a ...
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### Calculating Confidence Intervals SPSS [on hold]

Using the "Example Dataset," complete the following: Based on a normal distribution curve, calculate the probability of an individual being 60 years or older in this population. SPSS formulas ...
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### Difference between Multivariate Regression vs Iterative Regression on Residuals

Suppose one has an n × 2 matrix X (the independent variables) and a n × 1 vector y (the dependent variable). In a standard multiple linear regression setting, we solve for the 2 × 1 beta vector that ...
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### can i use logistic regression in discrete feature types

can i use logistic regression in discrete feature types problem. Since recently i knew that the expression for logistic regression is derived from guassian naive bayes and we can use guassian naive ...
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### Can knn be used for multivariate multiple regression?

I am working with MLB data with around 15000 observations for seasonal player stat. The data frame's structure looks like this (I'm making up the stats): ...
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### What test should i use to prove A is better than B [on hold]

I have sets of data that have number of goods produced by 2 machines, A & B for 2 months. Each machines has two numbers that is plan value and actual value. I'm not really familiar with hypothesis ...
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### Is it appropriate use the Binomial Theorem to analyze the problem of rolling dice?

In mathematics, the multinomial theorem describes how to expand a power of a sum in terms of powers of the terms in that sum. It is the generalization of the binomial theorem from binomials to ...
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### Looking for an statistical method [on hold]

A large data containing the amount of SO2 concentration from the exhaust of cars in the USA is available. Let's say I am a car company agent and the USA government asked me to come up with a "maximum ...
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### Can anyone hep me to find the probability of the following question please? [on hold]

The organizers of a banquet at a restaurant have ordered 10 place settings, but they have invited 13 people. Past experience indicates that 15% of the people who are invited independently decide not ...
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### ARIMA forecast confidence intervals

Can someone explain how confidence intervals for ARIMA forecasts are derived? I can't seem to find any good explanation of it. From what I've read it seems like because an ARIMA process can be ...
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### Does Neural Net with Softmax activation function violate the IIA assumption?

Multinomial logistic regression have assume the IIA (independence of irrelevant alternatives (IIA), IIA assumption: difference logit and probit); but I'm wondering if using Neural network in which the ...
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### Why do I get a different p-value when using summary(table(DF)) vs. chisq.test(table(DF))? [on hold]

I have a dataframe (DF) that consists of 2 variables with ~43500 observations. The first variable is a numeric (1-6), the other is a factor with 2 levels (PRE & POST). Why does R give a different ...
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### Calculating a baseline probability model for images

I'm a newbie to statistics, so I apologize if this question is trivial. I'm trying to build a distribution that can predict a specific set of images. But first, I need a baseline - so, I decided to ...