Questions tagged [statistics]

The study of the collection, analysis, and interpretation of data.

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28
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3answers
4k views

Is it necessary to conduct a power analysis before beginning an experiment?

I know that power analysis is the statistically valid way to ensure you use the correct numer of samples or repeats in an experiment. But I have never seen any biologist actually conduct a power ...
20
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3answers
3k views

How statistically significant was the “sweaty T-shirt” experiment?

An Overview of the Experiment. In 1995 there was an experiment that involves young people smelling T-shirts worn by another gender and rating their preference. The researchers found that people ...
14
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3answers
3k views

Do biological phenomena follow Gaussian statistics?

I have recently entered the life sciences (from physics). I am concerned about the use of p values in the life sciences literature. For example, in this article, they test 9 - 12 rats in a control ...
14
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1answer
16k views

What is the difference between a mechanistic and a statistical predictive model?

The simplest description of the difference between these two approaches that I have found are on this site who summarise the difference as: Mechanistic model: a hypothesized relationship between the ...
12
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3answers
3k views

How best to count bees entering and leaving a hive to measure hive activity?

This is my first question here, so I apologize for all mistakes I could have possibly made. I'm a high school student in East-Central Europe and I need to complete some research for a biology contest ...
12
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1answer
225 views

Systems identification in small neural network

When analyzing data from cortex, we often try to understand what each neuron does in terms of its inputs from other neurons - a specific kind of a systems identification strategy. Most current ...
12
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1answer
182 views

Biostatistics: Pollen dispersal directionality

What Information am I looking for? Think about a tree that is sending pollen all over the place. Because of wind, most pollen grain will go toward one direction. Imagine, we split the 2D area around ...
11
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2answers
6k views

What is the difference between naive and adjusted p-values in a GWAS study?

What is the difference between a naive p-value and an adjusted p-value in the results of a GWAS study? See from this paper: After Bonferroni adjustment, a single gene, DCTN4 (encoding dynactin 4) ...
11
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1answer
154 views

What is the base cancer rate for an arbitrary carcinogen?

Are all carcinogens equally potent? Is the relationship between dose and probability of cancer roughly equal, or are there some carcinogens that provoke cancer significantly more than their cousins?
10
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5answers
12k views

How many (taxonomic) families are there?

Approximately, how many families have been identified? I've often often come across figures for the total number of species on Earth. Recently, I found myself wondering about the encompassing ranks ...
10
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1answer
7k views

What is Mendelian Randomization, and how is it used to infer causality in epidemiology?

Studies of human traits and diseases are inherently confined to observational studies, known as epidemiological studies. This can make it very hard to determine what actually causes a particular ...
10
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1answer
2k views

How does population stability evolve?

The number of individuals constituting a population is called population size. Over time population size does not remain constant, it fluctuates to different extent over generations because of ...
10
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2answers
246 views

Statistical method for characterizing the relationship between body mass and metabolic rate

There is a dataset that contains body mass ($x$) and metabolic rate ($y$) from many different organisms. It is common to fit the data to the model of the form $y=ax^b$ and estimate the parameters $a$ ...
9
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1answer
13k views

How should species density be calculated for a clumped distribution?

Lets imagine 5 plots of different size are sampled for a target species: ...
9
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2answers
403 views

Can I compare Shannon indices of metagenome gene data?

I'm comparing 12 Metagenomes. I'm using HMM counts of a number of proteins known to exists as groups within certain operons. I have grouped the HMM counts for each type of operon and calculated the ...
9
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1answer
3k views

A timeline of the odds for survival for fertilized eggs and fetuses

I'm looking for data to build a timeline of the odds for survival of a fertilized egg, i.e., What are the odds it'll last a week? What are the odds it'll last a month? 2 months? (and so on until)...
9
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2answers
105 views

Can we disambiguate competing molecular mechanisms of learning and plasticity by measuring electrical activity of neurons?

I have been reading with fascination about the several molecular- and cellular-scale mechanisms and structural changes that underlie what we refer to as long-term plasticity. For instance, [1], [2], [...
8
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2answers
174 views

A mathematician's confusion regarding parametric $t$ tests for gene expression data

I'm a mathematician trying to test some things on gene expression data, and I'm thus skimming over various articles such as Sotiriou et. al. to understand what is typically done with such data sets. ...
8
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1answer
30k views

What is the optimum length of abstinence for maximum ejaculation volume in humans?

There have been papers discussing this, and whether the abstinence period should be 1 week, 2 weeks or other [1, 2]. Some think the time to maximum ejaculation volume is even longer than this. doi: ...
8
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1answer
178 views

PDB Mining: Why Do I Find Atoms Less than 1 Angstrom Apart?

I am attempting to find potential Hydrogen bonds between Hydrogen donors and aromatic ring acceptors. I do this by predicting the location of Hydrogens on residues and then calculating how far these ...
8
votes
1answer
116 views

Estimation of species range fragmentation

While discussing species distribution patterns along spatial, temporal or functional gradients one often finds a hump shaped species richness pattern. This is well documented in many taxa and spatial ...
7
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1answer
711 views

Understanding F-statistics in population genetics

I am reading the classic Weir and Cockerham 1984 paper about $F_{ST}$ estimation. At the beginning (first page, right column), they define 3 statistics. $F$ is the correlation of genes within ...
7
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0answers
276 views

How to estimate heritability from breeding data

I have a lot of plant-breeding data (tens of thousands of results) that are composed of phenotypes of parents and offspring. The plants however went trough years of selection and it is not balanced. ...
6
votes
1answer
7k views

What does conditional analysis of a SNP in a GWA study entail?

I am familiar with the use of tag-SNPs in genome-wide association studies to identify gene loci involved in complex traits, but I keep seeing the term "conditional analysis" used without any ...
6
votes
1answer
105 views

Don't understand figures in this citizen-science mosquito ID project

The Citizen-based mosquito monitoring system is a Citizen-Science vector tracking project that involves using any of a wide variety of cell phones to capture "sound bites" (sorry!) of ...
6
votes
1answer
352 views

What are the units of Phylogenetic Independent Contrasts (PICs)

PICs are a popular phylogenetic comparative method and I was wondering what units the actual contrasts are in. I want to say they are unitless but I am not entirely sure.
6
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1answer
99 views

Independent contrasts with non-homologous traits

I have morphometric measurements for a trait across various animal taxa, and would like to study the relationship between the size of this trait, and the animals' body size. In theory, I can account ...
5
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1answer
561 views

Where are the statistics for vaccine side effects?

My son told me that that during a discussion at school someone mentioned statistics about side effects of vaccines (I assume that the discussion was about standard vaccines in France). The numbers ...
5
votes
1answer
323 views

Why estimate linear and full (linear, quadratic, and correlational) selection coefficients separately?

"We then fitted a linear regression including all three life-history traits to estimate the vector of linear selection gradients, β, for each sex (Lande and Arnold 1983). A quadratic regression ...
5
votes
1answer
93 views

Are there any online resources one can use to access raw clinical trial data without having to contact those involved in the study?

I want to do some statistical analysis and I have a preference for real data so I was wondering if there's somewhere I can get such data for free without a heap of bother in phoning those involved in ...
5
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1answer
102 views

Is “aggregate percentage” still a valid term in ecology?

Martin et al. 1946 define "aggregate percentage" as a metric that describes the mean percentage contribution of a group to the total mass/abundance of all samples. The metric is useful in datasets ...
4
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2answers
3k views

What are the odds of being an albino human and have Down syndrome?

I know the odds of a human to be an albino. In Europe and the US it is 1 in 20,000 people (source) and for Down syndrome it is 1 in 1,250 (source). So that means the chance of giving birth to a child ...
4
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4answers
2k views

Why cancer mutations do accumulate sequentially?

According to Knudson hypothesis, cancer mutations accumulate in order. Statistics says, that cancer probability increases as sixth order of age, which may mean six consequential steps to cancer. But, ...
4
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2answers
2k views

Why Poisson Process for neural firing?

I am new to the world of neuroscience and I would like to understand how come every paper in neuroscience that I read uses a Poisson process to model neural firing. Do I just have a biased sample of ...
4
votes
1answer
639 views

Appropriate statistical test for a student lab?

I am a HS Bio teacher and doing a microevolution lab involving candy. Essentially students use four candy types and push them together until one cracks (Nat Sel). They also do simulations of migration,...
4
votes
1answer
207 views

Bayes theorem for mutations

MEN 2A is a dominant inherited disease caused by a mutation in the RET proto-oncogene. The probability of being sick when you have the mutation of the RET proto-oncogene varies with age and is assumed ...
4
votes
2answers
1k views

What's the proper way to determine whether dose response curves +/- another variable (besides dose) are statistically different?

I have an experiment wherein I measured uptake of a certain molecule into cells when delivered using Carrier A vs Carrier B. In other words, for example, I delivered 1, 2, 3, 4, 8, and 10 nmoles of ...
4
votes
1answer
435 views

What equation to compare protein isoforms in a Western Blot?

The protein isoforms I am interested in comparing appear as distinct bands on the gel I have already run. I have an Excel sheet with optical density measurements I obtained using ImageJ; it looks ...
4
votes
2answers
285 views

Different Effects of Detection Probability Between Presence and Count Data at the Same Location

I'm modeling habitat suitability for a large, mobile animal using occurrence data (presence only - I have no true absence data in this case) collected from camera traps (stations with automatic motion/...
4
votes
1answer
303 views

Are people genetically predisposed to being interested in specific fields/ideas? How does specialization occur?

I'm not sure if I formulated my question well, but I'm curious about a couple statements made by Steven Pinker and and James Heckman. In this interview: http://www.youtube.com/watch?v=KJ9Ad6s8g7I&...
4
votes
1answer
4k views

Index of ecological niche overlap

What is the Pianka's Index? How does it work? How can one calculate this index? How often is it used? In what context do people usually use it? Can one infer any statistical significance with this ...
4
votes
1answer
484 views

How can I calculate Shannon-Wiener diversity index in caves with different kind of habitats and different sampling methods?

I would like to start a monitoring in different caves, compare caves of different age and length, and find out if there are any correlations between these factors and their diversity. I was thinking ...
4
votes
1answer
237 views

Using Canonical Correspondence Analysis on matrices with missing data

I have a matrix of sites where not all the environmental variables I want to assess were sampled. In other words, there are sites with the whole set of variables sampled, and there are other sites ...
4
votes
0answers
55 views

What is a good approximate functional form for an equation relating plant growth to sunlight?

Question is in the title. I've got daily measurements of daily mean shortwave radiation at the surface, and annual measurements of plant growth (some measure, be it height or biomass or something). ...
4
votes
0answers
387 views

Minor Allele Frequency (MAF) higher than 0.5? [closed]

I have a set of data in PLINK format (*.bed, *.bim and *.fam files). There are around 2000 individuals in my dataset. I used PLINK to calculate allele frequencies in the population: ...
3
votes
1answer
214 views

What percentage of individuals infected with COVID-19 don't have symptoms?

There are various statistics estimating mortality of COVID-19 infections, based on how many diagnosed people have died. These numbers are used by various media to extrapolate how many people will die ...
3
votes
1answer
60 views

Log-tranformation and GWAS

Before doing any GWAS (genome-wide association study) it is necessary to check for the normality of the phenotypic distribution. If the phenotype is normally distributed only once it is log-...
3
votes
1answer
131 views

Distinguishing Father from Brother

Given the (non-identical) DNA sequences of two men and the knowledge that the second man is either the father, brother, or son of the first man, is the DNA useful in determining which of these three ...
3
votes
1answer
468 views

Why perform imputation?

Genetics datasets contain measurements for millions of single nucleotide polymorphisms (SNPs). Some (usually small) percentage of these values are of low confidence, and are labeled as missing values. ...
3
votes
2answers
384 views

Choosing appropriate statistical test for ordinal data

Ordinal response variables show up often in biology, but I'm not sure how they are best analysed. Some examples are qualitative assessments (little, many, a lot) or risk assessments (low risk, medium ...