# Tagged Questions

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### Co-occurrence Poisson binomial distribution

I'm using a Poisson binomial distribution for co-occurrence testing. I've 2 variables : X ~ Binom(px,n) and Y ~ Binom(py,n) (px and py are the probabilities, and both variable have the same number of ...
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### Help with binomial probability sample test formulation

This is a natural experiment, so I can not 'resample': My population has a property with 9 possible values: 1,2,3,9. Each value has a probability associated with it. For example 1's occur 10% but ...
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### Combining p-values from different statistical tests applied on the same data

Although the title of the question appears trivial, I would like to explain that it is not that trivial in the sense that it's different from the question of applying the same statistical test in ...
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### The correct probability distribution / way to identify large deviations in a set of daily changes to portfolio value

I am working on a report which is being sent through to end users that should flag to them any "large changes" in the day-to-day values for the past 30 days. These values are day-to-day differences ...
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### Problem with p-values from A/B testing

I'm pretty confused right now and the more I look at it, the more confused I get. Overthinking! I'm doing some A/B tests for my website. I'm using the significance calculator that's in this article: ...
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### Conservative confidence interval

One month before the election, a poll of a large number of randomly selected voters showed 65% planning to vote for a certain candidate. The newspaper article reported a 90% conservative margin of ...
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### Difference between chi statistical methods (pearson/likelyhood/linear-by-linear)

Can someone briefly explain the differences between these three tests? When would you use one over the other? Which tests are associated with a test of independence, homogeneity, or goodness-of-fit? ...
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### Chi squared test of homogeneity

Suppose you want to test the null hypothesis: H0: p1 = 0.65, p2 = 0.27, p3 = 0.01, p4 = 0.05, p5 = 0.02 to determine whether a population's distribution matches the proposed proportions. You ...
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### Population with known distribution (not normal) versus small sample

I have a complete population consisting of 6587 individuals (genes) and for each individual I have a distance value. These distance values are not normally distributed. I'm interested in determining ...
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### Finding the z score and p-value of a binomial distribution

Emily is a big fan of lady gaga, and 20% of the songs on her ipod are lady gaga songs. Suppose Emily has her ipod on shuffle and repeat mode, which can be assumed to mean that each song to be played ...
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### Why doesn't this represent a normal approximation to the binomial?

Suppose the registrar's office at a college reports 58% of the students live on campus. An intern working in the administration building is unaware of this 58% parameter value. He designs a study in ...
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### I want to compare two groups of coin tosses with different number of tosses

I have a list of results of two different groups of coin tosses generated by http://www.wolframalpha.com/input/?i=10+coin+tosses. But the number of tosses is different: There are 10 in one group and ...
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### P values and t statistics?

I performed an experiment using two different methods on same object, the results of the experiments were Method 1 70,72,70,75 and 77% Method 2 80,81,67,75 and 82% On basis on average I claimed ...
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### Distribution of $R^2$ for pairs of random variables

if I have two uniform random variables $X$ and $Y$, and I sample $N$ values for each, what's the probability of getting an $r$ Pearson's correlation coefficient (or Spearman correlation) between them ...
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### Frequentist properties of p-values in relation to type I error

This question is related to frequentist properties of p-values and their relation to type I error and why the results from an online simulation differ from what I would have expected. Assume that I ...
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### Comparing and contrasting, p-values, significance levels and type I error

I was wondering if anybody could give a concise rundown as to the definitions and uses of p-values, significance level and type I error. I understand that p-values are defined as "the probability of ...
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### Confidence interval and probability - where is the error in this statement?

If someone makes a statement like below: "Overall, nonsmokers exposed to environmental smoke had a relative risk of coronary heart disease of 1.25 (95 percent confidence interval, 1.17 to ...
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### Probability of head in coin toss is not exactly 1/2!

I kinda heard that usual coins are not exactly fair. The experiment done way ago and one done relative recently could reject the null hypothesis of p=1/2 after maybe hundreds of thousands of coin ...
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### Compare the difference of two probabilities or a ratio of probabilities?

In an experiment with continuous-value random variable, e.g. measuring length of cucumbers. I would like to compare the probability of getting a particular length range in two different conditions. ...
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### Effect of uncertainty in a parameter of a probability model on decisions — follow-up

I wrote this question which was previously answered I am exposing several experimental organisms to a toxin in the food. If the dosage is high enough, they will die. I am examining the number ...
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### How to choose significance level for a large data set?

I am working with a data set having N around 200,000. In regressions, I am seeing very small significance values << 0.001 associated with very small effect sizes, e.g. r=0.028. What I'd like to ...
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### Effect of uncertainty in a parameter of a probability model on decisions

I am exposing several experimental organisms to a toxin in the food. If the dosage is high enough, they will die. I am examining the number that are dead after a day. For practical reasons, the ...
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### Does an exact test always yield a higher P value then an approximated test?

I ran a simulation on that for mcnemar test, and the answer seemed to be yes. I was wondering if this can always be said to be the case that the exact P value is higher (or not smaller) then the p ...