# All Questions

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### Understanding the CDF of the Exponential from the PDF?

Recently, I was trying to get the CDF of the exponential through the pdf. I know that the relationship between the pdf and the cdf is that the pdf is the derivative $\lambda exp(-\lambda x)$. But I ...
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### Z-test question

Example from wiki: Suppose that in a particular geographic region, the mean and standard deviation of scores on a reading test are 100 points, and 12 points, respectively. Our interest is in the ...
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### Predicting value with MLP neural network

I am trying to predict a value using feedforward and back-propagation network but I get incorrect predicted value. I checked the gradients calculation and error is 1.79684799923e-11 < 1e-9 so ...
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### Need new strategy for single class classifier

I am attempting to create a single class classifier where the classes are fairly close to balanced (+/- 25). My dataset has ~2,800 samples and ~1,100 features. All of the features are binary except ...
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### Estimating parameter of a distribution for some generate random number

I just new in R for solving my statistical problem. Currently I'm working to estimate the parameters of a distribution using 200 random numbers (RN) that I generate using R. I generate 200 RN in 100 ...
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### Compare scores calculated for two groups who overlap?

I have three groups of ten children (A, B and C). They are each have different treatments (the treatments are to do with how they are taught about a certain biological feature). Two scores are ...
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### Help with interpreting results of simulation

In my homework, we were asked to discuss the results of performing the following do.file in STATA. I don't have a solid grapple with this format, so I wonder if anyone could start me off: ...
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### Chance that a vector of observations come from one distribution versus others

My question relates directly to the question at Test to what population an observation came from but I would like to know how to update the information about each possible distribution given ...
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### Classification of data with statistics

I have rainfall data series for a particular city. With the help of statistics i would like to classify the data of rainfall into light rain , heavy and very heavy. Is it possible to know the ...
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### ANOVA showing 0,00 value while I only want it to show 1 and 2 value

I'm currently working on my bachelor thesis but came across something that I can't fix myself. When running an ANOVA I get the following output: I want to make the 0,00 value gone because now I ...
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### Can I get a meaningful false positive rate from an A/~A classifier (ie, with no meaningful true negative count)?

I have an application that basically circles things in images. I need to find the false positive rate. Wikipedia says it's given by (number of False Positives) / (number of False Positives + number of ...
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### Survival analysis to model waiting times for buses

I need some way to model what is the expected waiting times when someone can take one of a set of buses, with different time/frequency characteristics. Bus 1 - There are 10 buses an hour, but ...
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### Data set generator

I'd like to ask if someone knows a good data set generator for multi-target/Multivariate regression All the best Richard
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### One Step Ahead with a forecast horizon of 25

I have 288 data points of the Wolf's sunspot data for the years 1700 to 1987. I need to predict one step ahead forecasts for a forecast horizon of 25. I kept the last 25 data points of the time ...
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### Effective sample size for MCMC with multimodal target

I am trying to evaluate an adaptive MCMC algorithm on a multimodal target density. Among other performance measures, I would like to evaluate the sampler in terms of Effective Sample Size (ESS). The ...
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### How to add hard negatives to original training data?

I have 2 class binary classification problem with original training data of size N=n_pos+n_neg in general case n_pos!=n_neg but now we can assume that number of positive and negative examples near the ...
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### how to run svm classifier on large data (1500 rows of csv file) in r studio [on hold]

here is the code , but i do not know the first step i.e about data frame ...
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### Zero-truncated Poisson model

In the theory of generalised linear models, you may use the exponential family to find the mean and variance of certain distributions. How would the mean and expectation of the zero-truncated Poisson ...
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### Correlation between two time-series of unequal size

How can I estimate some measure of correlation between two time-series of unequal size? Is it a good approach to interpolate to the same size? I just want to check for a trend in the values of a ...
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### Interpretation of the consistency property of a loss function

I am looking for an interpretation of the consistency property of a loss function used for classification (e.g., the SVM's hinge loss: $V(t)=\max(0,1-t)$). I copy from Wikipedia: Furthermore, it ...
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### Kaplan-Meier vs Cox proportional hazards survival estimates

I am conducting a 20 year longitudinal study on firm survival using a number of variable such as size, profitability, cash resource etc. What is the difference between the Kaplan Meier and Cox ...
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### Is the Jackknife estimation better than Maximum Likelihood Estimator?

I'm trying to estimate distribution parameters with Maximum Likelihood Estimator (MLE) and Jackknife estimator based on it. The estimation statistic is mean. Jackknife estimator is considered to be ...
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### do(x) operator meaning?

I have seen the $do(x)$ operator everywhere in some literature review I am doing on Causality (see, for instance this wikipedia entry). However, I cannot find a formal and general definition of this ...
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### Non-linear function optimisation using nlminb function in R

I have been getting error messages in my attempt to estimate parameters in a non-linear function using nlminb function. The following is the code: ...
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### In-sample and out-of-sample prediction [on hold]

I am going to forecast delta of profitability (Expected - long-run). I use several estimation : OLS and LOGIT. The approach is cross-sectional, so sustainability is assessed by reference to averages ...
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### R lmer error: Model is not identifiable. Error in base::chol2inv(x, …) : 'a' must be a numeric matrix [on hold]

I'm very new to using R, and I've been trying to perform some ANOVA analyses using both lsmeans and difflsmeans via lmer. The code that I'm using was given to me by someone who knows what they're ...
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### EM algorithm increase after E step?

It might be a silly question, but here it goes. The short version of my question is whether the marginal likelihood calculated after every E steps should be increasing or not. More details: Using ...
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### help with a statistic question. I did most of the work. (null hyothesis) [on hold]

Can someone help with these questions. I did majority of the work. but some i need help with. Are the mean number of times a month a person eats out the same for whites, blacks, Hispanics and ...
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### What statistical test can I use to compare the fluctuation of a feature over different datasets?

I have a recording of an instrument that can be divided into N sections (scale, single notes, music excerpt and so on). For each section, I divide the signal into short frames and I extract a value ...
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### Do p-values assume an unlikely event has already happened?

According to this thread What is the meaning of p values and t values in statistical tests? a p-value essentially lets me compare the probability of tail-end (unlikely) events occurring and judging ...
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### Practicality of James-Stein Estimator

It is well known in the literature that for a $d-$dimensional gaussian random variable, James-Stein estimator has a lower mean-squared-error than the 'ordinary' sample-mean estimator (for $d>2$). ...
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### In a random forest algorithm, how can one intrepret the importance of each feature?

I am in the process of building a Random Forest algorithm in MATLAB using the TreeBagger function. In the documentation, it returns 3 parameters about the importance of the input features. My ...
I am looking for most suitable model for count data in the following case: we collect number of patient's visits in a hospital for $t_i$ days ($t_i$ varies across subjects) some patients died ...