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15 views

Multivariate Generalized Linear Mixed Model [on hold]

I'm trying to run a multivariate generalized linear mixed model on a data set. I have 4 response variables, 3 fixed factors, a covariate and a random factor. SPSS can't do the analysis. I've tried ...
2
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0answers
29 views

Is there a standard formula/calculation for sexual dimorphism?

Is there a standard, or most accepted, way to present a value for sexual dimorphism? For example, one could use $$\frac{\text{Female value}}{\text{Male value}} -1$$ This would give negative values ...
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1answer
35 views

Multi-modal distribution for gene expression data

Why would some genes have more than two modes in their expression distribution? What external factors would cause this anomaly? I'm referring to the expression distribution of a gene across different ...
0
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0answers
25 views

What log transformation and normalization functions are most commonly used for microarray and how to select them?

Need help on rational approach to choosing log transformation, standartization and normalization functions in microarray experiments. I am using Expander software and it provides Log2 transform and ...
2
votes
2answers
53 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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1answer
44 views

Local BLAST Copy Number per Hit

I generated a series of local BLAST databases using makeblastdb of metagenomic data and am searching for the presence of a particular gene. While I can do the normal BLAST analysis looking at ...
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0answers
236 views

Additive genetic variance components from LMER in R

I've set up some dummy data in R which makes 40 genetically related lines, they are all siblings within a line so are genetically related by a factor of ½ thus additive genetic variance should be ...
2
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2answers
164 views

On evolution statistics [closed]

This basic evolution theory question has been haunting me since childhood and I'm kind of embarrassed that I can't explain it yet: Consider a butterfly. It's wings have evolved to look like the eyes ...
0
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1answer
58 views

Needing help in order to infer the statistical hypothesis tests performed in an old paper

I am in great need of help in order to infer the statistical hypothesis tests performed in an old paper. However I need to make some reasonable guesses only from the abstract of the paper since the ...
0
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1answer
116 views

Gene pool simulation [closed]

this simulation, you sampled the gene pool without replaceing beads in the beakerafter you drew each one. Thus, f(A) and f(a) in the gene pool changed slightly after each bead was drawn. For example, ...
1
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1answer
355 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 ...
3
votes
1answer
45 views

Why genes are assumed to follow multivariate normal?

I wonder why gene expression data are very frequently modeled by multivariate normal distributions. What is the reason for those strong assumptions that the genes follow multivariate gaussian? Are ...
1
vote
1answer
75 views

Niche overlap Index

I wanted to use the compana() function from the adehabitat package. I don't really understand the meaning of the data in the ...
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3answers
8k views

Deciding between chi square and t test

I am always so confused whether to do a chi square test or a t test in the sums given by my biostats teacher. Does anyone have a simple rule to decide this?
1
vote
1answer
117 views

Standardized Selection Ratio (SSR)

In this article the athors used the Standardized Selection Ratio (SSR) in order to infer what is the preferred host (anemone) of anemonefish. Here is a quotation coming from their methods: ...
2
votes
1answer
34 views

Material on the analysis of (micro)array data

I'm at the moment analyzing cytokine array data. The available material on the statistical analysis of these data is more than unsatisfactory. Since a lot of effort is being made in the analysis of ...
5
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1answer
222 views

Are descriptive statistics sometimes more useful than tests of significance?

How does the biology community currently feel with regards to publishing descriptive and effect size statistics rather than significance stats? Almost every journal article I read in the cell biology ...
4
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1answer
109 views

Is there a correlation between incidence of type 1 diabetes and vitiligo?

Does the data indicate that if you have one, the probability of you having the other is higher than that of someone who doesn't have the one?
9
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1answer
118 views

Is bootstrapping an acceptable way to determine standard error for binding constants? [closed]

I'm measuring binding constants my system and I appreciate the usual methods of using replicates to measure standard errors and using those errors to calculate propagation of error. I'm curious if ...