This tag is very ambiguous. Use it when none of our more specific tags will work better: [fishersexact], [fisher-information], [ronald-fisher], or [fisher-transform].

learn more… | top users | synonyms

0
votes
0answers
19 views

Type-II error and permutation tests

I am doing a permutation to know if two datasets are significantly different. These datasets, both, have a median of 1 (in fast, 60% of observations in one datasets and 80% of the other dataset are ...
0
votes
0answers
22 views

Integrating p-values (or z-scores) with missing values

I would like to apply a Stouffer (or Fisher) integration on a list of p-values or z-scores. However, some of them contain missing values. E.g. (R snippet): ...
3
votes
1answer
87 views

What are methods I can use to calculate the two-sided Fisher exact test?

I am implementing code to compute the two-sided Fisher exact test of 2x2 contingency tables in C. I read that R's implementation is not the most efficient way to calculate the p-value for a two-sided ...
0
votes
1answer
305 views

Post-hoc Tests for Fisher's Exact Test

I am running a series of Fisher's test to analyse some 2x2 contingency tables with small values. I have found significance. Is there anything equivalent to Cramer's V or the Odds Ratio or some sort of ...
5
votes
2answers
337 views

When combining p values, why not just averaging?

I recently learned about Fisher's method to combine p-values. This is based on the fact that p-value under the null follows a uniform distribution, and that $$-2\sum_{i=1}^n{\log X_i} \sim \chi^2(2n), ...
1
vote
1answer
785 views

Fisher's exact test in R - 2x4 table

I have a question on categorical data - I have a 2x4 matrix and I want to test the difference in the number of males or females in each group, and so I entered the data into R. So I input this: ...
1
vote
1answer
85 views

Sample variance Fisher consistency

I am reading conflicting references regarding the Fisher consistency of the sample variance. $$s^2 = \frac{\sum_i^n (x_i - \bar{x})^2}{n}$$ Could anyone explain me how to proof whether $s^2$ is ...
0
votes
0answers
36 views

Tests of independence for measurements of different magnitudes

Say there is a count table of observations Exon 1 Exon 2 Normal 1000 70 Disease 400 10 This gives a significant p-value if a ...
3
votes
0answers
98 views

Is Fisher overestimating the variance here?

[NB: the title of this post used to be "Please help me decipher Fisher on ANOVA". I've edited the question to make it more focused, and modified the title accordingly.] Since anything written by R. ...
1
vote
0answers
131 views

Test of 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 ...
4
votes
2answers
220 views

Computing p-values

I am a computer engineer, living in a digital world. I have no probabilistic background besides a probability course in the University and tried to grasp the Fisher's idea and have got the following ...
2
votes
1answer
124 views

Distribution of p-values from multiple experiments

My experimental setup is the following: compute an optimal solution $S$ to problem $A$ on instance $I$, evaluate test statistic $f(S)$, compute $f(S_i)$ for $S_i$ $(0 \leq i \leq n)$ drawn from a ...
2
votes
1answer
806 views

Fisher's method for combing p-values - what about the lower tail?

I have a bunch of independent p-values and now I want to combine them using the Fisher's method. Each of the individual p-values is coming from a one-sided test. I am just a little bit confused about ...
2
votes
0answers
207 views

Fisher's method when p-value = 0

I have a bunch of independent p-values and now I want to combine them using the Fisher's method. However, in R, when the p-value is zero, the log(p-value) becomes ...
1
vote
1answer
88 views

how to calculate E[vech(x x')vech(x x')']?

Supposing a vector x follows normal distribution. I want to calculate the expectation of the "fourth moment" in a vector form, meaning $\text{E}[\text{vech}(x x')\text{vech}(x x')']$, given that we ...
2
votes
0answers
121 views

Apparent fallacy in Fisher-Irwin test

For a hypothesis $H_0\equiv p_1=p_2$ (for two Bernoulli distributions), we take a measurement and find that $X_1=i,X_2=j$, and we denote $k=i+j$ Now, to test $H_0$, the Fisher-Irwin test tells us to ...
3
votes
2answers
310 views

Interpreting p-values

I am a little confused about what p-values mean under Fisher's signficance testing & Neyman-Pearson's hypothesis testing. Fisher uses p-values as a continuous measure of evidence against a null ...
4
votes
0answers
83 views

Orthogonal intersection in a Riemannian manifold

Let $S$ be the set of all probability distributions on $\mathbb{R}$ and $S_n=\{p_\theta\}$ be an $n$ dimensional submanifold of parameterized family of probability distributions on $\mathbb{R}$ where ...
3
votes
1answer
137 views

Orthogonal intersection of linear family and exponential family

I asked the following question in MSE for which I couldn't get any answer yet. I thought this would be a better place for that question. In statistical maniolds ...
5
votes
2answers
220 views

Connection between Fisher metric and the relative entropy

Can someone prove the following connection between Fisher information metric and the relative entropy (or KL divergence) in a purely mathematical rigorous way? $$D( p(\cdot , a+da) \| p(.,a) ) ...
2
votes
0answers
233 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 ...
0
votes
1answer
126 views

How do you test for independence of k binomial variables?

I am analyzing some orthopedic data and our outcome is union vs. non-union of a fracture. One of our independent variables is whether or not the initial fracture was closed (skin intact) vs. open. ...
2
votes
1answer
188 views

Comparing two nominal-scale response distributions

I have data from an experiment that consist of nominal-scale responses that subjects made in two treatments (the treatments are between subjects, not repeated measures). I've provided my data in data ...
5
votes
2answers
904 views

Fisher discrimination power of a variable and Discriminant analysis. Algebra of LDA

Apparently, the Fisher analysis aims at simultaneously maximising the between-class separation, while minimising the within-class dispersion. A useful measure of the discrimination power of a ...
0
votes
0answers
62 views

Confidence intervals based on asymptotic normality

I wrote a report about confidence intervals based on asymptotic normality. However, my supervisor said that the definition in the second paragraph is wrong, but I ...
4
votes
1answer
495 views

Fisher overall p-value vs. pairwise comparisons

I am doing comparisons on response rates across three sites. Following are the cell counts ...
7
votes
1answer
88 views

Enrichment analysis by gene duplication level

Biological Background Over time, some plant species tend to duplicate their entire genomes, gaining an additional copy of each gene. Due to the instability of this setup, many of these genes are then ...
1
vote
1answer
437 views

How to compare two sequences of binary data?

I have two differing-length sequences of binary values. In each sequence, each value corresponds to an observation which is either right or wrong. I'm looking for a statistical test that addresses ...
0
votes
2answers
252 views

Fisher classification method for normally distributed classes

As a follow-up to my previous question, I want to use Fisher's classification method (I mean, projection method) to project the data given the fact that the two classes are normally distributed. How ...
6
votes
2answers
439 views

Fisher Distance for feature selection

I'm currently working for EEG signal classification from 3 electrodes. I want to have a simple feature selection algorithm that is independent with the classification process. From the feature ...
1
vote
2answers
929 views

Which one consider when dealing with dummy variables: Exact Sig. (2-sided) or Exact Sig. (1-sided)?

I'm running a cross tab of one categorical variable against a dummy variable. This dummy variable indicates the presence or absence of a company characteristic(if the company is industrial it should ...
2
votes
0answers
1k views

Gamma distribution and Cramér-Rao bound

There are two definitions of the GAMMA distribution: I did the ML estimation, generated the Fisher Information, compared it to the Variance and the Cramer Lower Bound was reached, so the estimator ...
4
votes
1answer
364 views

Understanding Fisher's combined test

I am using Fisher's combined test to fuse several different independent tests. I have a problem understanding the results in some cases. Example: Let's say I run two different tests, both with the ...
1
vote
2answers
216 views

Testing if short sequence of small values drawn from binomial distribution

An experiment was run 10 times in configuration a and there were A failures, 10 times in configuration b giving B failures, 10 times ... (in all 9 different configurations). I have a list of 9 ...
16
votes
4answers
1k views

How to rigorously define the likelihood?

The likelihood could be defined by several ways, for instance : the function $L$ from $\Theta\times{\cal X}$ which maps $(\theta,x)$ to $L(\theta \mid x)$ the random function $L(\cdot \mid X)$ we ...
0
votes
0answers
50 views

F ratio and model comparison method to compute confidence bounds

I am working with Fisher Ratio. I compute this ration from a function that was already implemented in the software I am working on. But I would like to be sure that it does what I think it does. ...
3
votes
1answer
1k views

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 ...
4
votes
1answer
356 views

How to run K-means clustering on data points of varying dimensionality?

I'm trying to aggregate $T$ local image descriptors (i.e. histograms) into a vector, namely, the Fisher Vector as described in this paper by H. Jégou et al., Aggregating local image descriptors into ...
1
vote
3answers
180 views

Which kind of statistical test should I try for a sample with bivariate data?

I'm trying to analyze data from a questionnaire, showing graphical results. I used dispersion charts for correlating bivariate data with continuous and discrete ranges, showing also a trend line on ...
2
votes
2answers
782 views

Are Fisher's linear discriminant and logistic regression classifier related?

I have some experience with both FLD and LR for classification. On most data sets, I get very similar results, which raises the question - are FLD and LR related in some why? An idea, for example, ...
1
vote
0answers
150 views

Fisher's distribution and its approximation

I would like to ask how I can illustrate that Fisher's distribution when the null hypothesis is right goes to $F(k-m,n-k)$ when the degrees of freedom grow. How exactly is $F$ calculated in this ...
0
votes
1answer
186 views

Appropriate test for testing a pair of random binomial variables

I have pairs of values from two runs (replicate) for each sample along with total count for each run. I assumed each value as random binomial. I used log-likelihood ratio test to compare each pair, ...
5
votes
1answer
561 views

What does inverse-chi-square in Fisher method (classifying) exactly do?

In the book “Programming Collective Intelligence” Segaran explains the Fisher method for categorizing text as an alternative to Naive Bayes classifier. The Fisher method uses ...
3
votes
1answer
586 views

Likelihood ratio test vs. $\chi^2$/Z-test for comparing binomial datasets

When does/can one use the likelihood ratio significance test instead of Fisher's exact test or its Pearson $\chi^2$ approximation for comparing two binomial datasets? Given two binomial datasets ...