# Post List

## All posts; Tags Include "Probability and Statistics"

• September 5, 2015
• 07:21 AM
• 1,162 views

# Are internal replications the solution to the replication crisis in Psychology? No.

Most Psychology findings are not replicable. What can be done? Stanford psychologist Michael Frank has an idea : Cumulative study sets with internal replication. ‘If I had to advocate for a single change to practice, this would be it.’ I took a look whether this makes any difference. A recent paper in the journal Science […]... Read more »

• September 3, 2015
• 07:23 AM
• 1,024 views

# Why are Psychological findings mostly unreplicable?

Take 97 psychological effects from top journals which are claimed to be robust. How many will replicate? Brian Nosek and his huge team tried it out and the results were sobering, to say the least. How did we get here? The data give some clues. Sometimes the title of a paper just sounds incredible. Estimating […]... Read more »

• March 7, 2015
• 11:17 AM
• 1,433 views

# How radiation from space affects the Earth's climate

Convergent cross-mapping analysis finds 'modest causal effect' of cosmic rays on global temperatures over short timescales, but rules out effect on long-term global warming.... Read more »

Tsonis, A., Deyle, E., May, R., Sugihara, G., Swanson, K., Verbeten, J., & Wang, G. (2015) Dynamical evidence for causality between galactic cosmic rays and interannual variation in global temperature. Proceedings of the National Academy of Sciences, 201420291. DOI: 10.1073/pnas.1420291112

• October 20, 2014
• 01:12 PM
• 1,384 views

# How a camera and quantum physics could improve phone security

New study uses mobile phone camera to detect light, using shot noise to generate true random numbers which researchers hope could be used for encryption in the future.... Read more »

Sanguinetti, B., Martin, A., Zbinden, H., & Gisin, N. (2014) Quantum Random Number Generation on a Mobile Phone. Physical Review X, 4(3). DOI: 10.1103/PhysRevX.4.031056

• October 16, 2014
• 03:19 PM
• 920 views

# Is Axon Guidance by Attraction and Repulsion, or by a Roll of the Dice?

Attractants and repellants guide axons to their targets.  On its journey, a migrating axon may be confronted with multiple attractive and repulsive guidance cues.  This presents a conundrum. How does the axon avoid a tug-of-war between attractants and repellants?  Does the strongest cue win?  Can one cue negate the effects of another?  Can an axon switch its responsiveness to cues until they all match?   0 0 1 83 474 Robert Wood Johnson Medical School ........ Read more »

Tang, X., & Wadsworth, W. (2014) SAX-3 (Robo) and UNC-40 (DCC) Regulate a Directional Bias for Axon Guidance in Response to Multiple Extracellular Cues. PLoS ONE, 9(10). info:/10.1371/journal.pone.0110031

• October 15, 2014
• 03:49 PM
• 904 views

# A Random Walk into the Genetics of Axon Guidance

The man claimed he was a wizard and had cast the “spell of attraction” on the target.  Now the target would guide his arrow to the mark.  So we gave the man a broken arrow and watched to see if this arrow could hit the target.  The man took the arrow and flung it at the target.  Indeed, this arrow too could hit the target. Credit: Nina Matthews PhotographyPerhaps we had asked the wrong question.  Instead of looking at whether the arrow made it to the target........ Read more »

• October 13, 2014
• 11:37 PM
• 833 views

# The Attraction of Axons; the Moth or the Spider?

An axon is attracted towards its target by guidance cues.  A moth flies towards the source of a pheromone.  A spider is sucked across the floor towards the nozzle of a vacuum cleaner.  Is the attraction of an axon towards its target more like the movement of the moth or the spider?credit: pmillera4External molecules direct the movement of the axon, the moth, and the spider.  In response to pheromone molecules a moth directs its movement toward the source of the pheromone.&nbs........ Read more »

• October 11, 2014
• 12:09 AM
• 743 views

# Axon Guidance Meets Statistical Physics

The proposition that the response of an axon to guidance cues is a random walk provides a different perspective of axon guidance.For the most part, Biologists like deterministic models, i.e. cause and effect.  From the deterministic point-of-view, axon guidance is caused when axon outgrowth activity occurs at the site where the neuron detects an external attractive guidance cue. But what if the direction of axon outgrowth activity were to rapidly fluctuates in different directions?  In this ........ Read more »

• October 9, 2014
• 09:28 PM
• 721 views

# Random Walks, the Brain Initiative, and the Genius of Einstein's Brain

Over a four-month period in 1905, Einstein published a series of remarkable papers that changed our conception of time and space. Even more remarkable is the instrument that enabled Einstein to unlock the mysteries of time and space.  His brain.  Credit: internetarchivebookimages Some100 billion neurons allowed Einstein to think.  And in order to do this, the neurons in Einstein's developing brain formed a network of neural circuits.  By sending out process........ Read more »

• August 14, 2014
• 10:30 AM
• 1,715 views

# Competition for ecological niches limits evolution of new species | @GrrlScientist

A recently published study finds that competition for ecological niches limits the evolution of new species. Further, this study finds that speciation rate slows or even stops as available ecological niches fill up. Continue reading...... Read more »

Price Trevor D., Hooper Daniel M., Buchanan Caitlyn D., Johansson Ulf S., Tietze D. Thomas, Alström Per, Olsson Urban, Ghosh-Harihar Mousumi, Ishtiaq Farah, & Gupta Sandeep K. (2014) Niche filling slows the diversification of Himalayan songbirds. Nature. DOI: 10.1038/nature13272

Kennedy Jonathan D., Weir Jason T., Hooper Daniel M. , Tietze D. Thomas, Martens Jochen, & Price Trevor D. (2012) Ecological limits on diversification of the Himalayan core Corvoidea. Evolution, 66(8), 2599-2613. DOI: 10.1111/j.1558-5646.2012.01618.x

Harmon Luke J., Schulte James A., Larson Allan, & Losos Jonathan B. (2003) Tempo and Mode of Evolutionary Radiation in Iguanian Lizards. Science, 301(5635), 961-964. DOI: 10.1126/science.1084786

• June 16, 2014
• 04:26 PM
• 1,534 views

# Passenger pigeon extinction: it's complicated | @GrrlScientist

A newly published study reveals that the extinction of the passenger pigeon likely was due to the combined effects of their natural dramatic population fluctuations and human over-exploitation.... Read more »

Hung Chih-Ming, Shaner Pei-Jen L., Zink Robert M., Liu Wei-Chung, Chu Te-Chin, Huang Wen-San, & Li Shou-Hsien. (2014) Drastic population fluctuations explain the rapid extinction of the passenger pigeon. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1401526111

Groenen Martien A. M., Archibald Alan L., Uenishi Hirohide, Tuggle Christopher K., Takeuchi Yasuhiro, Rothschild Max F., Rogel-Gaillard Claire, Park Chankyu, Milan Denis, & Megens Hendrik-Jan. (2012) Analyses of pig genomes provide insight into porcine demography and evolution. Nature, 491(7424), 393-398. DOI: 10.1038/nature11622

• April 21, 2014
• 12:45 AM
• 1,365 views

# Cross-validation in finance, psychology, and political science

A large chunk of machine learning (although not all of it) is concerned with predictive modeling, usually in the form of designing an algorithm that takes in some data set and returns an algorithm (or sometimes, a description of an algorithm) for making predictions based on future data. In terminology more friendly to the philosophy […]... Read more »

• April 19, 2014
• 05:25 PM
• 1,043 views

# Monotonicity of EM Algorithm Proof

Here the monotonicity of the EM algorithm is established. $$f_{o}(Y_{o}|\theta)=f_{o,m}(Y_{o},Y_{m}|\theta)/f_{m|o}(Y_{m}|Y_{o},\theta)$$ $$\log L_{o}(\theta)=\log L_{o,m}(\theta)-\log f_{m|o}(Y_{m}|Y_{o},\theta) \label{eq:loglikelihood}$$ where $$L_{o}(\theta)$$ is the likelihood under the observed data and $$L_{o,m}(\theta)$$ is the likelihood under the complete data. Taking the expectation of the second line with respect to the conditional distribution of \(Y........ Read more »

Ruslan R Salakhutdinov, Sam T Roweis, & Zoubin Ghahramani. (2012) On the Convergence of Bound Optimization Algorithms. arXiv. arXiv: 1212.2490v1

• March 6, 2014
• 08:05 AM
• 1,731 views

# Evidence of the square root of Brownian motion

A mathematical proof of existence of a stochastic process involving fractional exponents seemed out of question after some mathematicians claimed this cannot not exist. This observation is strongly linked to the current definition and may undergo revision if nature does not agree with it. Stochastic process are very easy to simulate on a computer. Very […]... Read more »

• February 9, 2014
• 11:19 AM
• 1,520 views

Dennis Overbye is one of the best science writer around. Recently, he wrote a beautiful piece on the odd behavior of non-converging series like and so on to infinity (see here). This article contains a wonderful video, this one where it shown why and this happens only when this series is taken going to infinity. […]... Read more »

• November 15, 2013
• 09:30 AM
• 2,323 views

# Advancing Science Through the Use of “New Statistics”

There are several steps that researchers can take to bolster the integrity of their work, but embracing the use of the “new statistics” of effect sizes, estimation, and meta-analysis is a particularly important one, argues psychological scientist Geoff Cumming of La Trobe University in Australia.... Read more »

• November 4, 2013
• 09:53 AM
• 934 views

# Important statistical techniques in medical research

Main Point:

More elaborate statistical training is important for clinicians so that they can do research, and elaborate/interpret the medical findings better, according to a recent study.

Published in:

PLoS ONE

Study Further:

Researchers, in the present study, worked on the statistical techniques used in one of the most prestigious journals, Journal of the American Medical Association (JAMA), and found that the frequency and complexity of statistical reporting have increased in th........ Read more »

• August 29, 2013
• 11:06 AM
• 1,076 views

# Open-Source Energy Model for Policy Makers Will Increase Transparency

Computer models are used to inform policy decisions about energy, but existing models are generally “black boxes” that don’t show how they work, making it impossible for anyone to replicate their findings. Researchers from North Carolina State University have developed a new open-source model and are sharing the data they put into it, to allow anyone to check their work—an important advance given the environmental and economic impact of energy policy decisions.... Read more »

• August 24, 2013
• 05:27 AM
• 1,878 views

# Fossil fuels are more than just a bad habit

While my blog so far this year has shown how clear the case for fighting climate change is, our financial dependence on fossil fuels makes this difficult. But now divestment campaigns might be giving us a way to start untangling this sticky web. ... Read more »

Edward Hanna, Xavier Fettweis, Sebastian H. Mernild, John Cappelen, Mads H. Ribergaard, Christopher A. Shuman, Konrad Steffen, Len Wood, Thomas L. Mote. (2013) Atmospheric and oceanic climate forcing of the exceptional Greenland ice sheet surface melt in summer 2012. International Journal of Climatology. DOI: 10.1002/joc.3743

Cheung, W., Watson, R., & Pauly, D. (2013) Signature of ocean warming in global fisheries catch. Nature, 497(7449), 365-368. DOI: 10.1038/nature12156

• August 20, 2013
• 03:00 AM
• 1,263 views

# Black swans and Orr-Gillespie theory of evolutionary adaptation

The internet loves fat tails, it is why awesome things like wikipedia, reddit, and countless kinds of StackExchanges exist. Finance — on the other hand — hates fat tails, it is why VaR and financial crises exist. A notable exception is Nassim Taleb who became financially independent by hedging against the 1987 financial crisis, and […]... Read more »

Kryazhimskiy, S., Tkacik, G., & Plotkin, J.B. (2009) The dynamics of adaptation on correlated fitness landscapes. Proc. Natl. Acad. Sci. USA, 106(44), 18638-18643. DOI: 10.1073/pnas.0905497106