# Questions tagged [f-distribution]

The F distribution is a continuous probability distribution which is commonly used in statistical testing procedures.

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### Why does G*power calculate the noncentrality parameter in this way?(different from formula)

I'm calculating the power of some F-family tests and I found the key to the power was the noncentrality parameter (ncp). So I'm trying to calculate the ncp $\lambda$. However, I got different results ...
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### ratio of 2 chi square to get f-distribution

How can I use two chi square functions to make a f function? I only see invchisquare functions in some languages when I need to use an inv f-dist to get the exact binomial CI. So, looking to figure ...
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### $F$-test with a variance being $C$ times as large as the other

I am familiar with $F$-tests in which the alternative hypothesis is defined as $H_a=\{\sigma^2_1/\sigma^2_2>C\}$ (the sign "$>$" can be either "$<$" or "$\ne$" as well), where $C=1$. If I ...
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### Simulate CDF of sum of i.i.d. F distributions

I have trouble on simulating the CDF of a random variable Y, where $Y = \sum_{i=1}^{12} X_i$, and $X_i$ are i.i.d. F-distribution. I am doing this in MATLAB, the problem is that small instance of Y ...
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### Finding value of F distribution without special calculator or table?

When performing a t-test, the calculation of p-values related to this are given as: Is there a way to find $F(.)$ using a t-distribution table or a normal distribution table? (i.e. without a special ...
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### Distributions of variance and mean

I am adding this again with details as suggested The following questions were asked. State if true The test statistic for the difference of population variance follows an F-distribution The test ...
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### Which distribution should I use when building a GAM in R?

What type of distribution would you consider this data to be? My first thought is an f-distribution, but I suppose it could also be a poisson distribution. I am trying to build a generalized additive ...
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### What is a “log-F” distribution?

Recently I have encountered the Wiener-Granger causality test. The statistic which is used is the logarithm of the ratio of two residual variances. It is well known that the ratio of two such (...
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### “Under the ANOVA null, within group and between group sample variance are both estimates of the pop. variance” — why only under the null?

In Statistical Methods by Snedecor and Cochran, it states something to the effect of "the within-group variance is an estimate of overall variance given the null hypothesis" and this point is used to ...
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### Using R to calculate qt (t-dist) using qf(f dist) help?

I am having quite some trouble using R to calculate, say, qt(0.975,6) using qf instead of qt. I know the relationship between the t-distribution and the f-distribution which I understand as follows: /...