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# Questions tagged [degrees-of-freedom]

The term "degrees of freedom" is used to describe the number of values in the final calculation of a statistic that are free to vary. Use also for "effective degrees of freedom".

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### How many degrees of freedom in a T-copula is commonly used to model financial data?

I'm looking to fit some T-copulas to my financial return data. Unfortunately, the software I'm using can only fit a T-copula with a fixed degree of freedom parameter. So what parameter should I use? ...
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### Selecting degrees of freedom in stepwise regression (stepAIC function in R)

Context: I have data available on water quality in a number of catchments, for example the concentration of Zinc (Zn). For each catchment, I also have a range of characteristics (n=16), such as the ...
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### What is the motivation for the use of $n-m$ in the method of moments in Wedderburn 1974?

In an answer to this question Is there a Relationship Between Variance and Chi-Square? I wrote So to find the dispersion parameter, one has to use a different trick. In Wedderburn 1974 this is done ...
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### Degrees of freedom for biased sample autocorrelation function

I want to find the expression for the a biased estimate of the autocorrelation function for a time series $X$, and am doing this from the biased estimated autocovariance function for lag $k$, divided ...
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### Help with determining statistical significance of bees’ decisions [closed]

Firstly, my apologies for the basic nature of this question. I am numerate but stats has always befuddled me. I have had a look through earlier questions. I have installed a red mason bee box. It has ...
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### What is the reference edf for generalized additive models?

From the summary of my fitted generalized additve model (gam) I see two edfs. The first edf is the model edf and second is the reference edf. However, for AIC estimation, the reference edf is used. ...
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### Optimizing Treatment Group Assignments

When setting out experiments, I want to make sure treatment groups are as balanced as possible. Instead of using randomization, I've started to use the following process. I first collect some ...
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### What is the critical value for those df not listed in Critical value table for Pearson correlation?

What is the critical value for pearson correlation df=190? The total number of samples is 192, so df is N-2 = 190. The tables have critical values for df 100, 150, 300, 500, 1000. If the df (N-2) ...
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### What would be the sample number if two variables have different number of samples?

While correlating two variables, which have different number of samples in each, how can I find the df? Eg. Sample-A has 35 observations, Sample-B has 22 observations, How to calculate df (N)-2? ...
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### Clarifying degrees of freedom in fixed effects model

I'm new to econometrics and learning about fixed effects. If I understood it correctly, we are literally including dummy variables for every observations. For example, I have a panel data of firms and ...
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### Results from extractAIC() from a mixed model lmer() are confusing

I have some legacy code in larger block of looped code that compares models. It essentially boils down to this similar example: ...
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### Chi square reporting df for 2x1

I conducted a 2x1 chi square and need to report it in APA. There are 280 in the sample. Do I deduct the df from the sample size? e.g. X2 (1, N=279) Thank you
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### How to deal with potentially too few levels of the random effect

I built a linear mixed effect model with nlme with Body length, Habitat and Sex as fixed effects. Body length is added for body size correction while the other two both have two levels. In the random ...
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### Intuition behind rank of covariance matrix and testing hypotheses

I am trying to acquire some intuition about testing multivariate hypotheses where the test statistic involves inverse covariance matrix. As an example, suppose we have a $p$-variate random vector that ...
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### When fitting a generalised additive model, how to choose how much to smooth?

When fitting a GAM, is there a rule (of thumb) for deciding if $k$ (max number of degrees of freedom for a spline) is large enough or not? How much should edf be below $k'$? And is that an absolute ...
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### When transforming a dataset using the square root (or any other procedure), does the standard deviation of the dataset get transformed too?

Taking an introductory statistics course, and I am confused about the impact of a transformation on the df for a two-sample t-test. The df is dependent on n of each sample and SD of each sample, but I'...
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### What should be the degree of freedom in ANOVA table

Consider the area under wheat for a sample of 44 clusters selected from 11 different villages. Four clusters were selected from each of the 11 villages and each cluster consists of 8 survey numbers(...
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### Interpreting 'edf' from random factor smooth in GAM model

I specified a random factor smooth in the following way: ...
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### Implementation of Scheffe's adjustment in software

My understanding of Scheffé's adjustment for multiple comparisons is that it already adjusts for any possible contrast that one could make with the data, where the contrast coefficients sum to 0. ...
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### Effect of sample size on Chi-squared distribution

As the degrees of freedom increase, the chi-square curve approaches a normal distribution. But what about increasing the sample size? If I am using degree of freedom =1, but with different sample ...
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### Degrees of freedom in a 2^3 factorial experiment without three-way interaction included

I have an ANOVA model with 3 effects (A, B, C) with (a, b, c) levels each and 3 two-way interactions (AB, AC, BC). Within each cell there are n replicates. How to calculate number of degrees of ...
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### Should I use select=TRUE for mgcv::gam while comparing df? [closed]

While running a GAM (Generalized Additive Model), I noticed that using select=TRUE inside mgcv:gam I get different ...