# Tag Info

21

First, let's consider the original Wedekind et al (1995) study. Sample sizes seem reasonable, if the effect is not very noisy: [...] 49 female students (average age: 25.2 years, s.d. = ­4.0) and 44 male students (average age: 24.7 years, s.d. = 2.6) [...] ... and the statistical design accounts for individual differences in a fairly robust way: [...] ...

11

kmm's answer is correct; I just want to add some of my points on what kind of data should follow Gaussian distribution. Unless you know from observation that a process doesn't follow a Gaussian distribution (e.g., Poisson, binomial, etc.), then it probably does at least well enough for statistical purposes. I won't fault kmm for this statement ...

10

It is correct if (and only if) albinism and Down syndrome are independent events, that is, if albino people is not more nor less likely to have Down syndrome than non albino people (and vice-versa). However, doing a quick Google search I can't find any source relating albinism and Down syndrome, and therefore independence seems a reasonable assumption ...

9

One thing that's certain is that the activity of bees varies according to time of day, so more important than how long you record for is probably at what time you record. If you always record at the same time of day, this should allow a reasonable comparison between results of different days. For example, recording from time 14:30 to 14:35 every day could be ...

9

Mechanistic model answers the how question. These models are usually biophysically detailed, and designed to be causal. Say you discovered a linear relation between blood pressure drug and heart rate. This would be a statistical model. It doesn't tell you how the two are related biophysically. One could build a detailed model that describes intermediate ...

9

You raise two issues, both of which might be better suited for stats.SE, but I think the questions are suitably biological to warrant an answer here. Do most biological processes follow a Gaussian distribution? Unless you know from observation that a process doesn't follow a Gaussian distribution (e.g., Poisson, binomial, etc.), then it probably does at ...

8

The NCBI Taxonomy statistics page displays the following information: There are currently 73540 genera, 331418 species, and 23127 taxa of higher order. Since the number of taxa decreases with the genericity of the taxon, there are probably around 20000 families, give or take a few thousand.

8

(World Health Organisation, 2014. p. 2) shows the adverse effect (side-effect) rates for the MMR vaccine. For instance, fever between the 7th to 12th day after vaccination occurs in 5 to 15% of vaccine recipients and rashes occur in 2-5% of vaccines, etc. Page 6 summarises the results in a table. As you point out, the adverse effects are variable in ...

7

There don't appear to be many robust studies on this, but this study by De Longe et al in 2004 suggests that, whilst the volume of the ejaculate is increased after 5-days of abstinence (in most participants), for many this did not increase further after 8-days [1]. Here are the 11 participant included (along the x-axis), and for each participant there are ...

7

I'm assuming you're asking how to estimate population size based on numbers of individuals you capture. Yes, there are many approaches to this. The R library SPECIES-R offers a number of methods of calculating this. They are described in the manuscript SPECIES: An R Package for Species Richness Estimation. Some of the methods described are: Chao, A. (1984), ...

6

The 2011 paper How Many Species Are There on Earth and in the Ocean? indirectly answers this question as well as any other source you'll find I imagine. It estimates how many species there are total based on the rate of discovery of higher taxa; it includes plots of number of taxa over time for the major groups of life in Figure S1. Which gives: Animalia - ...

6

The Plant List has 642 families listed: http://www.theplantlist.org/1.1/about/#changes. For a quick comparison, Wikipedia lists 522 fish families: en.wikipedia.org/wiki/List_of_fish_families 136 mammal families: en.wikipedia.org/wiki/Mammal_classification 61 amphibian families: en.wikipedia.org/wiki/List_of_amphibians 57 reptile families: en.wikipedia.org/...

6

To me, there are two issues that are mixed up here (if I understand you correctly). First, do you want to estimate the mean and variance for a statistical population (i.e. to characterize a larger population by independent samples), or do you want to calculate the actual density for a particular area, where you have counted all occurences in that entire area ...

6

@bshane has already provided an excellent answer to the question. However, I just found a recent review published in Molecular Ecology (Winternitz et al., 2016) in which the authors performed a phylogenetically controlled meta-analysis on MHC-dependent patterns of mate selection in humans and non-human primates. They used studies from seven primate species ...

6

The histogram you show isn't a distribution of age-at-death for individuals, it's a distribution of life expectancies for different countries. The post you link takes data from a table on the Wikipedia page List of countries by life expectancy. Interpreting the histogram you posted, we see average life expectancy seems to hit a wall around 85. This does ...

6

A standard pipeline for DGE would be Salmon for (pseudo)mapping + DESeq2 for statistical analysis. Salmon is one of a set of modern, fast and accurate mapping software. Requires a transcriptome to be defined. DESeq2 is a mature R (Bioconductor) package which can handle reasonably complex designs, including time series, but not mixed models. The vignettes are ...

5

In GWA studies you tend to analyze your "lead" SNPs in regions where genotypes are correlated (known as linkage disequilibrium). If you find an association between another SNP with the outcome, and this SNP is correlated with the original variant, you can perform a conditional analysis where you adjust for the original SNP in the model. This is to test if ...

5

I don't know about other groups, but about plants, number of families depends on the system you follow. Recent version of The Plant List (1.1) estimates about 352 000 species of Angiosperms and lists over 400 families. See http://www.theplantlist.org/1.1/browse/A/ It is very good and reliable source of information. Second very good source about plant ...

5

To choose the right statistical method (it is more than just saying "use the t-test") you need to think about your experiment. A good starting point is this figure from Bitesizebio: There are two relevant articles on that website: Let’s Talk About Stats: Comparing Two Sets of Data Let’s Talk About Stats: Comparing Multiple Datasets Probably also ...

5

TL;DR: A sixth order probability curve of cancer does not mean six steps. The order of the curve has nothing to do with the number or sequence of mutations. Causes why ABCD could be more likely than DABC exist and have been extensively studied Repair and control ("defence") mechanisms are what does the 'ordering' of steps by selecting for mutations which ...

5

(This isn't an answer, but hopefully it will help get it past the experimental design into just solving the equation.) Where did you get that α0 was not determined from their data? On p. 10 (256), they state, "The prevailing direction of effective pollen dispersal within neighbourhoods (a0) that gave the best ﬁt of the model was 91 degrees from north (...

5

I don't understand your calculations and I don't understand why you're trying to use Bayes formula. I don't know the $\frac{1-p}{2-p}$ formula and I don't understand what it is supposed to calculate. It seems to me that you're overthinking a simple problem. We don't have all the information and need to make a bunch of assumptions but if I understand the ...

5

Probability of independent events Assuming the albinism and Down syndrome are independent traits, then the probability of having both traits is the product of the probability of having each trait. For more information see wiki > probability (especially the section on independent events). Albinism and Down Syndrome If (and only if) albinism and Down ...

5

You can read about the differences between a binomial and poisson distribution at this other question on Math.SE. First, since spikes are discrete events, it makes most sense to use a probability distribution that is discrete. A Poisson process is a process where an event occurs randomly with no "memory" for how long it has been since the last event. A ...

5

I took a class in ordination methods a few months ago and found the following books helpful in better understanding the various techniques: Multivariate Statistical Methods: A Primer by Brian Manley https://www.crcpress.com/Multivariate-Statistical-Methods-A-Primer-Fourth-Edition/Manly-Alberto/p/book/9781498728966 Correspondence Analysis in Practice by ...

5

It's a weekly cycle due to reporting disruptions over the weekend. Use a 7-day moving average to get a better picture. Holidays and such can still be disruptive but the 7-day average solves most of it.

4

Ideally, you would gather preliminary statistics to design the experiment. If you have a high variability, and your observation window is short, then small effects will be swamped by the variability. However, if what you are looking for has a big effect in the number of bees, then counting for a shorter time is going to be fine. A rule of thumb would be to ...

4

I suspect I won't be crunching as much numbers as you'd want me to, however here are some basic points: Statins have shown a clear ability to improve the blood llipid profile. Their use in primary/secondary prevention for cardiac events is justified by the belief that less blood lipid will leave less lipids to clog the arteries with. This is an old paradigm,...

4

I'm one of the STRING maintainers, so I hope I can clear things up a bit. Gene co-occurrence: genomic context methods are very useful for bacterial genomes, but not so much for eukaryotes. However, they are actually the most unbiased data we have, since there's no human influence (beyond selecting species for sequencing). Benchmarking: Interactions ...

4

This is directly following the advice of Lande & Arnold (1983), saying: Linear multiple regression can be used first to estimate the forces of directional selection, $\beta$, and their standard errors. Then a quadratic multiple regression (16) or (Al), can be used to estimate the forces of stabilizing selection, $\gamma$, with their standard errors....

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