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

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8 views

Repeating assays assessing drug synergy by Chou and Talalay method

I have been using MTT cell viability assays to test compounds, both as single agents and in combination, in a constant ratio. From these assays I have been able to plot the median effect plot to get ...
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1answer
14 views

Statistical genetics: Allele frequencies that follow a Dirichlet distribution

From Foll and Gagiotti (2008) (software BayeScan). They consider a model where several subpopulation are derived from a unique ancestral population. We consider a set of $I$ loci and let $K_i$ be ...
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1answer
30 views

Get Parent GO terms of GO term vector?

I have a vector of GOIDs that are specific GO IDs outputted from an enrichment analysis. I want to cluster my GOIDs by their parent GOID term. I used GOstats to do my enrichment analysis, and I have ...
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1answer
33 views

Given the number of individuals who have a recessive disorder, how can one calculate the probability that the disorder was inherited? [on hold]

Just to be clear, this is not homework. Suppose a biological family has five children, two of whom have a certain recessive genetic disorder that is not sex-linked. The parents themselves do not have ...
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32 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. ...
2
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35 views

Estimated protein size using CDs data [closed]

The number of amino acids in a protein is important to predict their size. I used coding DNA sequence (CDs) to predict the average of the protein size of E.coli k12 from a sample provided by the ...
3
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2answers
49 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 ...
9
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1answer
105 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 $a$ ...
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44 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 ...
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0answers
16 views

What is the best test for SNV clustering?

I am looking for a method to cluster single nucleotide polymorphisms based on clinicopathologic data (mainly receptor immunoistochemistry). So far, I've came up with only two that handle dummy ...
6
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1answer
1k 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 ...
5
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1answer
39 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 ...
3
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1answer
47 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 ...
9
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1answer
1k 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 ...
3
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1answer
76 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 ...
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0answers
39 views

How should one interpret heritability? Is it related to $R^2$?

From Wiki: Heritability estimates are often misinterpreted if it is not understood that they refer to the proportion of variation between individuals on a trait that is due to genetic factors. It ...
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1answer
3k views
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38 views

Large set of semen microscope images needed

As a course project I have to write an algorithm whose purpose is to analyze a sperm sample (total number, motility etc). In order to do that though, I need to have a sufficient number of images to ...
2
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1answer
44 views

Parametric Bootstrap Capture Recapture

I am using the (one sample) capture recapture for estimating hidden human population. One sample method uses purely frequencies of capture to estimate population. One of my colleague suggested ...
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1answer
189 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 ...
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1answer
84 views

How to statistically test the predictability of evolution? [closed]

Can anyone recommend me an experimental study which tries to test the predictability of evolution? The closest works I found are the studies of fluctuation tests (f.e. classical study of Luria & ...
3
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1answer
1k views

Index of ecological niche overlap

For this question I am interested in the Pianka's 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 ...
14
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1answer
381 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 ...
3
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1answer
99 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. ...
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3answers
1k 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 ...
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0answers
21 views

What techniques can be used to link environmental conditions to crop yield?

Im interested in how we can determine what are the optimal conditions for crops and how deviations from these optimal conditions affect yield. In the literature I have found two main approaches and I ...
9
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3answers
405 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 ...
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0answers
15 views

What is the best aCGH normalization procedure for hyper-ploid tumor samples?

I'm currently working on aCGH data of Triple Negative Breast Cancer patients xenografts and primary tumor samples. A substantial amount of my samples is highly aberrated which leads to offsets of the ...
6
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1answer
98 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.
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25 views

Does anyone use bootstrapping to report mass gain during experiment?

When performing an experiment to report gain of body mass in an experiment, do any of you know of a paper whose authors have used a bootstrap to improve their confidence intervals? I have a n = 10 ...
5
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0answers
76 views

Understanding F-statistics in population genetics

I am reading a classical Weir and Cockerham 1984 paper about Fst estimation. At the beginning (first page, right column), they define 3 statistics. $F$ is the correlation of genes within individuals ...
2
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0answers
79 views

Efficient algorithm to calculate various population divergence statistics

Intro and description of the data I am simulating the evolution of very long DNA sequences. The model works well, is performant and will output data in the following kind of fasta format ...
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33 views

Quantifying temporal-spatial data [closed]

Imagine a set of territories each subdivided into 5m grid cells. Each grid cell represents a spatial unit, and that unit can have any number of variables associated with it - e.g. habitat ...
4
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1answer
643 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: ...
6
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1answer
53 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 ...
4
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1answer
104 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 ...
2
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1answer
85 views

How to calculate the Jaccard index [closed]

I want to calculate the Jaccard index between two compounds. What is the algorithm? I have searched for it, it just gives the formula but how to apply it on compounds is not known to me. Can you help? ...
2
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1answer
59 views

About validation process of phenological study

I have recently done a phenological study using remote sensing techniques. Now I need to validate my results and my methods, that is, to determine if the phenology estimated from remote sensing is ...
4
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1answer
63 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 other those ...
11
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1answer
140 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 ...
0
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1answer
244 views

How to select genes before log2 ratio on a RNASeq gene expression matrix, based on signal median

I want to transform a TCGA mRNA expression matrix (in linear data format) to log2-ratios and then run a feature (gene) selection, selecting the 1000 most variant genes (genes with higher standard ...
2
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1answer
102 views

Correct/complete representation of RTPCR statistics

In papers reporting a relative quantification of gene expression by RTPCR, I often see a bar chart with mean ± standard error or deviation, with the deviation belonging to biological replicates. This ...
2
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1answer
69 views

Comparing gene expression levels between control and disease at different time points

I have a data set with expression levels of a list of genes, measured in replicate at two different time points between two groups; a control group and a disease group. I want to identify the changes ...
3
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2answers
158 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 ...
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0answers
68 views

“Gold standard” for CNV detection methods?

Is there a generally accepted "gold standard" for testing the performance of CNV detection methods? I'm interested both in learning about existing datasets that may serve as gold standards for CNV ...
1
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0answers
19 views

How to study the number of herbivores per type of tree and time of day?

Suppose I want to find out the number of herbivores in different kinds of trees, and also compare the numbers between day and night. How would this kind of study be run in practice? It easy to think ...
4
votes
1answer
133 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 ...
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0answers
52 views

Cigarette consumption dose-response function WRT health outcomes

I'm curious how health risks (mortality, lifetime probability of cancer, etc) change with cigarette consumption. Specifically, treatring cigarette consumption like a continuous variable, rather than ...
2
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1answer
349 views

(Updated question) Problem with Fold-change mean compared to absolute data (in qPCR)

For the problem below I am aware of the statistics involved but just can't get my finger around the following: In biology we use qPCR to measure gene expression or basically number of mRNA copies. It ...
2
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1answer
53 views

Data Bias in protein-protein interactions data

Databases like STRING have so many predicted as well as experimental interactions data for many organisms.However there is a bias in the data which they have?. a)The first is gene co-occurrence ...