Questions tagged [f-distribution]

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

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How to go from this formula to F distribution

I have the following formula. $$\int_{0}^{\infty} x^{\frac{n-1}{2}-1} (a+x)^{\frac{1}{2} \frac{-n}{2} -v} dx.$$ The quantities $d1 ,d2$ appearing in the pdf of the F distribution are the following. $$...
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Compounding Gamma with Gamma to yield F-distribution?

I am working through some problems from my Bayesian Statistics course and am having trouble understanding a step in the solution to a question. For reference this is the question: And here is the ...
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What is $F_{k,\infty}$, i.e., $F$ distribution when the second degree of freedom approaches infinity?

What is $F_{k,\infty}$, i.e., $F$ distribution when the second degree of freedom approaches infinity? I'm wondering if there is a known distribution(such as $\chi_k^2$) that it converges to.
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Distribution of $X'\Sigma^{-1}X$ for $X$ following a multivariate $t$ distribution

According to Golam Kibria & Joarder (2006, p.7) available here and Kotz & Nadarajah (2004, p. 19) visible in google, the distribution of $X'\Sigma^{-1}X /p$, for a known correlation matrix $\...
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Test for overall significance of regression when the variance of errors is known

Say we want to test the overall model adequacy in a multiple linear regression model: $$H_0: B_1 = B_2 = ... = 0 $$ $$H_1: B_j \neq 0 \text{ for at least one j}$$ the random errors $\epsilon$ are ...
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When a population is not normal, can F ratio be used for ANOVA analysis?

As it is known a F ratio assumes that the random variables in the numerator and denominator (variances in the case of ANOVA) follow a chi squared distribution, which is true for the sampling ...
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Transforming F-dist or long one tail

I have been going through different kaggle datasets recently to apply different techniques I have learned. I have seen loads of articles related to preprocessing your features with normalization or ...
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Derivation of F-distribution from inverse Chi-square?

I am trying to derive F-distribution from Chi-square and inverse Chi-square. Somewhere in process I make a mistake and result slightly differs from the canonical form of Fisher-Snedecor F distribution....
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Asking about the meaning of abbreviation f(1, 78)

Please I have a thesis defense and I wrote from this article this number f(1, 78) but I don't know what it refers to Can anyone clear it up for ME? THANK YOU
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Why we use the number of params as degree of freedoom in the F test for regression?

In a linear regression, we can assume that $\frac{(SSD_y - SSR)/p-1}{SSR/(n-p-1)}$ have a $F$ distribution if the null hypothesis $Ho$ is true, with $SSR$ being the sum of residues of the regression ...
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how to understand the logic of null distribution

In a statistics textbook I read the following about comparing two population variances by using independent samples: If a null hypothesis (stating that the ratio of two population variances is 1) is ...
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F test for linear regression - why only upper tail

In linear regression when considering the f test for slopes be it MLR or SLR, we only consider the upper tail probability for the p value. Here's a video for reference: link. Why is that? EDIT: as ...
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2 votes
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Prove that $Z = \frac{X_1}{X_2}$, has an F-distribution

Let $X_1, X_2$ be independent random variables following density law $f(x) = e^{-x} , 0 < x < \infty$, Show that $Z = \frac{X_1}{X_2}$, has an F-distribution. I thought of solving this by ...
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Prove that $P(X \le a) + P\{Y \le \frac{1}{a}\} = 1$

Prove that if $X$ has the F-distribution with $(m, n)$ d.f. and $Y$ has the F-distribution with $(n, m)$ d.f., then for every $a > 0$, $$ P(X \le a) + P\left\{Y \le \frac{1}{a}\right\} = 1 $$ I ...
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Why do we get different f-statistics for the ANOVA of two models in R if we add third model

For example, using the mtcars built-in dataset. A two-model ANOVA: ...
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Why doesn’t a $F$-statistic of 1 result in a $p$-value of about 0.5?

I’ve been presented with the following chain of reasoning. In an ANOVA, if the null hypothesis is true the F-statistic is expected to be about 1. A p-value is the probability of obtaining test ...
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Connection between t and F distributions [duplicate]

We have: $Z\sim N_{0,1}$ (standard normal distribution) , $U\sim X^2_{k}$ ($X^2$ distribution, with k df) with $Z \bot U$ Then $X = \frac{Z}{ \sqrt{U /k} } \sim t (k)$ (t-distribution, with k df) I ...
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In an F distribution, when would the first parameter, d1, ever be greater than the second parameter, d2?

It seems that when running an ANOVA, the degrees of freedom of the mean sum of squares between groups (SS_b) will always be less than or equal to the degrees of freedom of the (summed for all groups) ...
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F-Distribution: difference between the expected value for a random variable and the expected value of its inverse?

It is known that the expected value of the F-Distribution depends only on the degrees of freedom associated with the Chi-square random variable in the denominator. In other words, E[1/X] does not ...
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Expected value of the F-Distribution dependent on the degrees of freedom associated with the Chi-square random variable in the denominator?

0 The F-Distribution has a Probability Density Function that can be defined as: with an expected value of: What would be a logical explanation for why the expected value only depends on the ...
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F distribution definition with gamma function or square root [closed]

On wikipedia (https://en.wikipedia.org/wiki/F-distribution) I see the pdf of F distribution defined using squared root function, while other places I see the pdf defined with the gamme function. E.g ...
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Finding cumulative probability for F distribution

If Degrees of Freedom is 2 & 27, what would be cumulative probability for finding F-statistic higher than 1? Below are possible options. Option 1: 0.456 Option 2: 0.852 Option 3: 0.762 Option ...
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t-student or f-distribution?

I am reading 'Applied multivariate statistical analysis' by Richard Johnson and I do not understand that first to explain this test, talks about the t-student distribution. And then out of nowhere he ...
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Asymptotic distribution of intraclass correlation

Consider the random effects ANOVA model below (notation based on Snijders and Bosker, 1999), where $j$ represents a group and $i$ an individual: $$ Y_{ij} = \mu + U_j + R_{ij}, \qquad var(Y_{ij}) = \...
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Ratio of Standard Deviations from a Normal Distribution to an F Distribution

Apologies if the title is confusing, I couldn't think of a more apt title. I have that $W_i$s are iid $N(\mu_a,\sigma_a^2)$ and independent of $Z_i$s which are iid $N(\mu_b,\sigma_b^2)$. This means $...
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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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1 answer
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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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How to interpret $F > F_{\rm crit}$, but $p > \alpha$

My F is greater than F critical, while P-Value is 0.99 greater than alpha (0.05) which one should I consider the P value or F statistic, rejecting the Ho: I am confused. Edit: $$ \begin{array}{ccc} \...
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Why is this statistic F-distributed?

A book I'm reading claims that the statistic: $\frac{(RSS_0 - RSS_1) / (p_1 - p_0)}{RSS_1 / (N - p_1 - 1)}$ has an F distribution. Why is this? I know that an F distribution is something like $\frac{\...
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Does X^2 divided to DF converge to F distribution when X^2 is Rao Scott chi squared statistic?

I'm studying Rao-Scott chi-squared test, kind of survey sampling analysis method. It uses when we want to test independence between two variables under complex sampling data instead of Pearson chi-...
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From expected value of R2 in Regression to expected value of partial eta squared in ANOVA

In general, $R^2$, the estimator of "multiple correlation coefficient" in regression, is known to be positively biased. Given $K$ predictors, and $N$ total sample size, Johnson, Kotz, & ...
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Derive the distribution of the ANOVA F-statistic under the alternative hypothesis

Say we have $k$ samples of data, where sample $i$ is of size $n_i$ and we write it as $x_{i1}, ... , x_{in_i}$. Let the total sample size be $N$. The ANOVA model is $X_{ij} \sim N(\mu_i, \sigma^2)$ ...
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What is Cov(X,Y) when X,Y is a F-distribution (a,b) and (c,d) ,in case X,Y Not independent [closed]

I want to know Covariance of random variable between $X$ and $Y$ when $X$ is a F-distribution with degree of freedom $a$ and $b$ and $Y$ is a F-distribution with degree of freedom $c$ and $d$,in case $...
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The behaviour of the critical F per F distribution

I noticed that, for increasing degrees of freedom of the MSE (Mean square error / denominator in the F-ratio), the critical F declines. This is also the case for increasing degrees of freedom of the ...
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When should an F-test be one sided vs two sided? [duplicate]

If we increase both numerator and denominator degrees of freedom of the F distribution, then the pdf narrows down on the value 1. This suggests that a two-sided test is reasonable: If we have high ...
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What is the median of the non-central F ratio distribution

I am looking for a simple approximation to the median of the (simply) non-central F distribution with parameters dlnum, dldenominator, and ncp, the non-centrality parameter. Clearly, there is no ...
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Tail bounds for F-distribution (not using $\chi^2$ bounds)

Are there any sharp tail bounds for an $F_{p,q}$ distribution? That is, if $X \sim F_{p,q}$, then for a $t_1,t_2 > 0$, what are the sharpest $\delta_1$ and $\delta_2$ known such that $$P(X > ...
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Link between Fisher and Chi-squared

I am fairly new to statistics, and during practice, i used this link between Chi-squared and F-statistics where F equals to ration between 2 Chi squared distributions. Can someone elaborate more on ...
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2 votes
1 answer
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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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Inverse of a (singly) non-central F variable

It is known that if $X \sim F_{\nu_1,\nu_2}$ (F distribution with degrees of freedom $\nu_1$ and $\nu_2$), then $X^{-1} \sim F_{\nu_2,\nu_1}$. Is there any known similar result for $X \sim F_{\nu_1,\...
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How does one calculate the F-value-threshold used to evaluate an F-test?

I am studying Response Surface Methodology (by Myers, Montgomery, and Anderson-Cook). When introducing the significance testing for regression parameters, an $F$-test is introduced but only partially ...
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1 vote
1 answer
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Can you perform an inverse F-test on two datasets with the same degrees of freedom?

Stats newbie here. Is there any meaning to the critical F value if the two samples have the same degrees of freedom? For example, I have 2 sets of data, each with the same number of degrees of ...
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Convergence of F(n,n) distribution to normal

Suppose that $X \sim F(n,n)$, an F distribution on $n$ and $n$ degrees of freedom. I'm trying to figure out why some literature state that $X$ converges in distribution to a normal distribution. My ...
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What do you do if your degrees of freedom goes past the end of your tables?

The degrees of freedom in my F table don't go up high enough for my big sample. For example, if I have an F with 5 and 6744 degrees of freedom, how do I find the 5% critical value for an ANOVA? What ...
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-2 votes
1 answer
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F-Distribution formula

How did we get this formula? Can you explain it with visualization if possible? $$\text{Using properties of f distribution } f_{(1-\alpha), (\nu_1,\nu_2)} = \frac 1 {f_{\alpha, (\nu_2,\nu_1)}}$$
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2 votes
1 answer
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A question about Two-Sample poisson test [closed]

I read this paper: "Experiment Size and Power Comparisons for Two-Sample Poisson Tests", Wei-Kei Shiue and Lee J. Bain, Journal of the Royal Statistical Society. Series C (Applied Statistics), Vol. ...
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Confusion about greater variance in the numerator for F ratio

I am studying about F ratio and how, as a random variable, it follows F Distribution. So let me explain what confuses me. This is what the theory says -- We draw two random samples $sample_x$ and $...
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Compute a quantile of F distribution?

I'm looking for the meaning of this definition of $q$, found in a chapter on non-linear regression. "$q=q_{1-\alpha}^{F_{p,n-p}}$ is the $(1-\alpha)$ quantile of the $F$ distribution with $p$ and $n-...
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