Questions tagged [fisher-transform]

Fisher's z-transform is a transformation that is applied to the correlation coefficient, r, for use in hypothesis testing & constructing confidence intervals.

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Significance test of Fisher z scores

There are 14 vectors given, each vector has approx 3000 components that take vast range of values. I'd like to determine how closely linked they are or whether an independence could be assumed. I ...
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In what order should I perform Fisher's r-to-z transformation and correction for range restriction and measurement error on correlation coefficients?

I have a two part question; both parts relate to correcting/transforming raw correlation coefficients for the purpose of a meta-analysis. Confirming my understanding of ...
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Standard Error of semipartial correlation coefficient

I am trying to find out whether there is a way to calculate Standard Error for coefficients of semipartial correlation. I'm using the spcor function in ppcor package in R, and it actually took me a ...
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fisher transformation for pearson allows building a different confidence interval than for spearman?

I'm confused by the wikipedia articles for fisher transformation for spearman and pearson. It looks like for pearson, the confidence interval is built around $\frac{1}{2}ln(\frac{1+\rho}{1-\rho})$ ...
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'rma.mv' function output- fisher Z or raw correlation

I would like to ask a question regarding the output of the rma.mv function. I had raw correlations which I transformed into Fisher's Z correlations using the 'escalc' function. Then, I performed a ...
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Fisher transformation

I am currently working with panel data, namely its correlations. The data is three-dimensional. I am looking for a way to aggregate the correlation coefficients. I found a model which uses the Fisher ...
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93 views

When testing Pearson's r, when should I use r-to-t transformation instead of [Fisher's] r-to-z' transformation?

At least two tests are common for testing the significance of a Pearson correlation coefficient. Comparing $t=\frac{\sqrt{r^2/(1-r^2)}}{\sqrt{\frac{1}{N-2}}}$ to Student's $t$-distribution with $N-2$ ...
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249 views

Why is fisher transformation necessary?

I read that the correlation coefficients have to be converted by using a fisher-transformation when one wants to test their significance (like here When is Fisher's z-transform appropriate? ). I ...
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Simple mean or weighted mean of Fisher z-transformed correlation coefficients

I need to perform the average of a set of correlation coefficients $\rho_i$ with $i=1,\ldots,m$. I follow the standard prescription: apply the Fisher z-transformation to my $\rho_i$ ($z_i$ are the z-...
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37 views

How to calculate Mean Sample-Based Reliability Estimates Used for Analyses

I am conducting a meta analysis of Pearson's r , of correlations presented between test scores and job performance ratings. I need to present an uncorrected effect size and an effect size corrected ...
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45 views

Average sample size of two fishers z correlations

I am conducting a meta analysis of Pearson's r correlations. As there are two correlations , sometimes three , for the same study and dependent variable I have averaged the correlations via fishers z ...
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88 views

Averaging of two or more standard erros

I have calculated two standard errors for two fishers z correlations from the same study , both measuring the same variable. Is it acceptable for me to average the two standard errors into one? If so ,...
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What is the name of this random variable?

Let $X \sim \text{Normal}(\mu, \sigma^2)$. Define $Y = \frac{e^X -1}{e^X+1}$. The inverse transformation is $X = \text{logit}\left(\frac{1+Y}{2}\right) = \log\left(\frac{1+Y}{1-Y} \right)$. By the ...
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Fisher Z transformation vs T-Test in cross sectional correlations

I want to compare the correlations of stock related measures. According to the paper referenced below, time series can be compared for statistically different correlations with the Fisher Z ...
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Fishers-R-to-Z - published study reporting value I can't replicate

I am reading a paper that reported a significant difference in correlation between age and some measure between groups. It looks like they calculated the Fisher's-R-to-Z wrong? I wonder if someone ...
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Fisher z test to compare correlations in a time series

I am running an analysis (in SAS, using proc corr fisher). http://core.ecu.edu/psyc/wuenschk/docs30/CompareCorrCoeff.pdf I basically want to know how different the correlations are on a daily basis ...
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Doing the equivalent of a dependent t-test on a sample of correlation coefficients

I’m doing an analogy of the following study. I take participants etc. and show them a picture of man 1 and have them rate his attractiveness and rate his intelligence just from his picture. I then ...
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213 views

fisher r to z test with different number of observations between variables.

Is there a way to test whether the correlation coefficient between two variables with a shard third variable is significantly different, if the sample sizes are different? Here is the case, ...
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Can someone explain the Fisher transformation and why it is used in layman's terms?

I am writing a paper on comparing different business cycles and have calculated bilateral correlation coefficients between individual countries and the overall aggregate. I have read in some of the ...
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792 views

Reporting Fisher-transformed Pearson's correlations when the magnitude of difference is relevant

My field regularly demonstrates a certain type of result with pairwise Pearson's correlation matrices between predicted and measured data. As soon as such correlations become high, Fisher-transforming ...
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4k views

Fisher R-to-Z transform for group correlation stats

I have independent correlation coefficient measures for each subject. I would like to test whether the correlation coefficient of the group is significantly different from 0. My understanding is ...
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305 views

Is Fisher's z transformation necessary when comparing the variances of correlation coefficients?

I am working on functional connectivity between brain regions, where functional connectivity is represented by the Pearson correlation coefficient between the time series (fMRI) of brain regions. I am ...
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564 views

Significance testing between two mean correlation values

I have collected 50 data points from 9 individuals for 4 variables, say, a,b,c,d. For each individual, I correlated ab and cd using a Pearson correlation. Aim: I would like to test whether across ...
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Difference Between Two Correlation Coefficients - questions

I’m working on an exercise to check if a difference between two correlation coefficients is significant. However, I have certain doubts after I did some reading about the topic. My data consists of 2 ...
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924 views

Averaging correlation coefficients

I am calculating Spearman correlations multiple times between individual data vectors that are not necessarily of the same length. So for example, ...
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713 views

Statistical significance test for averages of correlation coefficients

My setting looks like that I have several subjects $i$ (let's say 5) and for each subject I measure the lists/vectors $A_i$, $B_i$, $C_i$ and $D_i$. Then, for each subject $i$, I calculate the ...
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What is Bartlett's theory?

This neuroimaging paper has been cited thousands of times. In it, a method is proposed for computing the correlations among several seed regions and all other brain voxels. Part of this method ...
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Confidence interval for correlation

I know the confidence interval of an estimated correlation can be calculated after performing Fisher transformation. But I never figured out why. I also couldn't find the explanation online. Can ...
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785 views

Bootstrap confidence intervals

I write to you for 3 questions. I want to calculate confidence intervals on different measures of association (Pearson's correlation coefficient, Cramer's V and the Eta-square). I will make the ...
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Special case of Fisher Z for comparing two correlations

I'm a statistical consultant, one of my clients requested something I haven't heard of before: She wants to compare the correlation between X and Y (two ratio scaled variables) before an intervention, ...
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11k views

Fisher's z-transform in Python?

I want to test a sample correlation $r$ for significance ($n=16$), using p-values, in Python. As I have understood from this question, I can achieve that by using Fisher's z-transform. Is there a ...
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391 views

Calculating CIs for $\eta^2$ via Z scores - sample size?

In the thread Confidence Interval for $\eta^2$ it was proposed that if only limited statistics are available (in my case, F, df1, df2, means), one could calculate the 95% CI for $\eta^2$ by: ...
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Significance of average correlation coefficient

Disclaimer: if you find this question to be too similar to another one, I happy for it to be merged. However, I did not find a satisfactory answer anywhere else (and do not yet have the "reputation" ...
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Testing significant difference between two determination coefficients $R^{2}$ for two PLS-based structural equation models

Two structural equation models were tested (one was based on a sample with 199 individuals and the second one on a sample with 93 individuals). The aim was to test whether the results of the first ...
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When is Fisher's z-transform appropriate?

I want to test a sample correlation $r$ for significance, using p-values, that is $H_0: \rho = 0, \; H_1: \rho \neq 0.$ I have understood that I can use Fisher's z-transform to calculate this by $...
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950 views

How to Test the Difference between 2 Sets of Pearson Correlations?

Suppose I have two sets of Pearson correlation coefficients -- call them set A & set B, and they are of the same size. How do I systematically compare the correlations in A against B? E.g., I want ...
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661 views

Statistical significance of increase in correlation

I have a sample with some individuals, and also three variables measured for each individual, let's say $A$, $B$ and $C$. There is a mild correlation between $A$ and $B$ and a mild correlation ...
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Spearman's rank correlation for a beginner: Sample size and Interpretation

I am a computer scientist performing research, which includes calculating the Spearman rank correlation of two lists, one ranked by a human, another by a computer program. I have the following ...