# All Questions

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### Should I use Pearson or Spearman correlation (and is it even correct)?

so I'm doing the following: for a research paper at university I want to calculate the correlation between top grossing ranks and rating scores of mobile apps. I pulled the data from an analytics site ...
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### Can I use Cumulative Logistic Regression in spite of violation of proportional odds assumption?

I have an ordinal outcome variable with the following levels (unlikely, somewhat likely, very likely) that I want to tests in an Adjusted Regression Model with about 20 predictor variables (including ...
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### Feature Selection when LASSO sets all coefficients to zero

I am trying to select features for a data set that contains what food people have eaten with a result of BMI. However, since I want to see what foods impact BMI most I am trying to use various forms ...
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### Convolution of a multivariate Gaussian and multivariate exponential distribution

I have derived the convolution for a multivariate Gaussian distribution with a multivariate exponential distribution. By having such a distribution in place, one can have the best of both worlds: ...
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### Use of count in Stata

I am using the data set of Verboven cars1.dta Download here. Then, I use egen yearcountry=group(year country), label and ...
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### What do I do when my model prediction exceeds the limit of 100%?

I have plotted the effects of a model glm( A ~ B, family=poisson, data=data) both with the sjplot R package and with the ...
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### Marginal effects in multinomial logit in R

I am trying to calculate average marginal effects (dF/dx) for a multinomial logit model in R. Package mfx provides the solution only for binomial (and not the multinomial) model. Is there a package or ...
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### Are parametric tests only subject to ratio and interval scale measurements?

I had doubts on the above flow chart based on measurement scales which I found in a published article. Can anyone correct m please and clear my doubts as I believe non parametric tests are not ...
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### Is IV really invariant to the number of bins?

I read several times that "the IV formula is fairly invariant to the number of bins". This is no very intuitive to me, because: IV is a sum of positive numbers (one number per bucket). Therefore, if ...
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### Measure the distance between two probability transition matrices

I have a probability transition matrix $P$ that contains some values very close to zero. I want to sparsify this matrix by taking the k largest values for each row and setting the others to zero. For ...
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### Testing the consistency of two sets of measurements

Suppose I'm measuring a quantity $X$ twice, $x_{1}\pm\sigma_{1}$ and $x_{2}\pm\sigma_{2}$. $\sigma_{1}$ and $\sigma_{2}$ are in general not equal to one another. If I want to know if the two values ...
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### scikit-learn IsolationForest no variance feature

I'm using IsolationForest algorithm in order to detect anomalies in my data and to use this model to detect future anomalies in new rows and came across a few questions: Is the model good for ...
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### Why does the test statistic of a 2 Sample K-S test change drastically when noise is added to samples?

I believe I have gone through all 2 Sample K-S test related posts here, but I could not see the answer to my problem. At this point, I don't know whether the problem is related to a bug in the ...
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### p-values in multiple linear regression depend on number of predictors?

So I am wondering if there usually is any "correction" being made to p-Values (of single predictors) if you add more predictors to the model? Does anybody know how SPSS handles this? I am well aware ...
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### Product of normal random variables and exponential random variables is exponential random variables?

How we can prove analytically, the Product of normal random variables and exponential random variables is exponential random variables?
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### Weighted average Sufficient Statistic

I have the following question about sufficient statistic: suppose that you have N agents indexed by $i$ and $j$ each starting with a noisy signal $x_i^0 = \theta + \epsilon_i$ where $\theta$ is a ...