# All Questions

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### Using single line chart with multiple, unrelated, data sets?

I would like to visualize two unrelated sets of data using a single line chart to check for any "correlation" (it's just for fun - nothing that claims to be statistically accurate). Just as an ...
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### Slope analysis where one group is not normally distributed

I am currently doing analysis of five separate drug groups and their changes in levels of prescription over time. Having done linear regression on excel I am comparing the 'steepness' (m) of the ...
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### Regression choice with endogenous variables

I am attempting to analyze the relationship between the quantity of oil demanded and the price of oil. The price of oil is an obvious endogenous variable, so regressing (OLS) quantity on price (with ...
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### Hypothesis Testing for small sample

I am a somewhat dubious about how to apply some hypothesis testing for this case or maybe it is not applicable at all. In an undergraduate Algebra course, the Faculty has been using a book from ...
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### Does this variable follow a poisson distribution or a binomial distribution?

I dance an average of 2/7 nights during a week. D = Number of nights dancing in one month/4 weeks. My first thought was Poisson, but am now unsure. Is it none of the above?
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### Skewed Classification Problem

So I've read around and seen this is a problem. I have a classification problem and 12 variables ... I'm working on getting more, but even if l get the number to 20-30 I feel like the problem will ...
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### Overlapping interval of a Poisson arrival process

Calls arrives according to a Poisson arrival process with rate lambda = 15. Find E(N(2,4]N(3,5]) My thoughts: E(N(2,4]) = E(N(3,5]) = lambda * t = 15 * 2 = 30 However, I cannot figure out the next ...
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### problems in doing logistic regression with unbalanced sample, give me some references

I have a dataset with lots Y=0 and few Y=1. I have to run logistic regression, so I'm using a retrospective sample in order to get a more balanced sample. Could someone give me some references that ...
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### Is my interpretation of the numerical gradient versus network output correct?

I have implemented a neural network with back propagation using a sigmoid activation function. To validate the functionality of my code, I am estimating the gradient of my function using the ...
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### Which statistical test for statistical significance of positive result in 5 categories of samples

I have 5 categories rock samples and I am trying to understand how their fossil preservation differs and whether the difference is statistically significant. I determined the presence or absence of ...
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### Sample size of sampling distribution of the sample mean

When people say that the mean of the sampling distribution of the sample mean is equal to the population mean, is this true regardless of how small or large the size of the samples are? I'm having a ...
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### Why do we need confidence intervals?

I am following a video lecture on Statistics, which introduces the concept of confidence intervals in the following way: "A bank vice president is interested in the average checking account balance ...
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### Determine statistical significance of web server response times

I am trying to analyze the performance of a web server. I've pulled from the logs a sampling over seven days of the hits for each individual page. From a histogram of the response times, I see that is ...
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### Is my data normal graphical vs. analytical test

I am trying to determine if my data is normal. I am using R. I run the jarque bera test that has a NULL hypothesis of Normality ...
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### Choice based conjoint latent class analysis in R

How can we perform Latent class Analysis for choice based conjoint data, to both segment respondents and determine co-efficients for attributes at the same point of time? I know there is a package ...
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### How can I test for changes in the distribution of categorical data over time?

Each week at my organization, we receive X number of type A messages, Y number of type B messages, Z number of type C messages...etc. I want to be able to test if the distribution of these message ...