# All Questions

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### Goodness of fit test for exponential distribution

The given data below shows the time in intervals in seconds between successive white cars in flowing traffic in an open road.Can these be modeled by an exponential distribution. ...
28 views

### Regression for outcomes truncated from both sides

I have an outcome which is truncated from both left and right sides. I would like to know which regression method may account this kind of analysis. Here is an example: ...
29 views

### How to exclude interaction effect in linear regression modelling?

I am working with biological dataset. I am looking for significantly differentially expressed genes that stand out under effect of 3 different factors (e.x. gut microbiota level has/not, tissue, ...
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### What kind of test to use for measuring a factor during time?

I am working with microbiological data. I want to test how gut microbiota is developing in my samples. I have one base line, which doesn’t have any gut microbiota, and then by day 1 they receive ...
14 views

### Noncentrality parameter in two-sample-t-test (Power analysis)

I am working with R, doing a post-hoc power analysis. Can anyone explain to me why these two commands generate different outputs? I thought they should not! ...
15 views

### Difference between MANOVA and two-way ANOVA

I have read the articles of both of these statistical methods on wikipedia, and as far as I can tell they are used in the same cases. I could not tell in how far they work the same way, since the ...
10 views

### Can I improve nnet model by assigning input weights?

I'm working with nnet package in R. I'm using it for prediction (classification) purposes of 17 inputs and 1 output. Output is either 1,0 or 2. (Similar to iris data set classification example). I ...
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### Reduce the number of data points to a maximum in a series

I have maximum 8 series with datapoints. Sometimes the amount of this datapoints of a series is over 500. In worst case i have around 8*90.000 datapoints. I don't need to draw so much because you ...
22 views

### Interpretation of p-value for one-way ANOVA and two-way ANOVA

We are currently handling some results and performing some ANOVA tests on human search performance in virtual environments using different sound systems for audio rendering. We measure the time it ...
24 views

### Neural network for prediction

I am working on Neural Network for a regression problem in R using packages like nnet, caret etc. I have split my data into train, validation and test. My doubt is does the train() function in caret ...
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### How to print table from packet in R? [on hold]

In package MASS there is data Insurance packet. And I need to: Print table, which row will be Group and column will be Age, in the table should be the sum of Claims meaning. Can someone help me to ...
18 views

### Measuring variation of one data set with respect to another data set

Each of the points in the plot below is a mean of 1000 samples. The standard deviation of a point on the RED line is "small" in that it is smaller than the difference between the mean of the RED line ...
39 views

### Book/Website recommentation on probability distributions usage

Is there a book(s) / Website(s) that list the different type of distributions and real world usage or application for each one of them (beyond the typical know ones such as normal, binomial, poisson, ...
27 views

### Ordinal regression models vs. nominal regression models

Suppose we are trying to decide whether to use an ordinal regression model or a nominal regression model. If we know that the outcome variable is ordered should we still use a nominal regression model ...
11 views

### Trying to Refine SARIMA models

I have a SARIMA forecast from statewide Real Estate Sales data.. but I'm not happy with it. The SARIMA parameters are confusing to say the least. I am finding that the current model is not ...
24 views

### Statistical test when there was no attempt to match cases with controls

An examination of nickel levels in the lungs of nine cases who died and nine controls who did not die was performed. The data are cases: 65,24,52,86,120,82,399,87,139 controls: 12,10,31,6,5,5,29,9,12 ...
19 views

### Does true correlation in statistics represent validity coefficent as used in psychometrics?

The statistics appears to have borrowed certain concepts and models from psychometric theories and models. Is it a correct to presume that the two terms are equivalent?
18 views

### Katz backoff for n-gram language models

I have defined unigram, bigram and trigram (language) models with my training data. Now I am checking their fitness towards a test data by using Katz backoff with a fixed discount of 0.5 (mo ...