Thursday, March 12, 2015

Rosetta probe to start listening for the lost lander Philae

possible Philae landing area

Rosetta scientists think Philae landed somewhere in a boulder-filled landscape (circled). In this image taken 20 kilometers from the comet, Philae would be no larger than three pixels.


ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA


Are you there Philae? It’s me, Rosetta.


On March 12, the European Space Agency’s Rosetta probe will start listening for a signal from the lost lander Philae, missing in action since its rough landing on comet 67P/Churyumov–Gerasimenko on November 12. Rosetta’s orbit is taking the spacecraftover Philae’s suspected hideout, so for the next eight days, Rosetta will send a signal to the lander and listen for a response.


As the comet swings around the sun in the coming months, Philae might be able to recharge its solar-powered batteries. Engineers don’t expect to hear from Philae just yet, but given that Rosetta will be in the neighborhood, they have decided to try.


Wednesday, March 11, 2015

Bionic power trousers could be a more comfortable way to independent living

Definitely the wrong trousers, too much chafe. Colin Hurst, CC BY

The word “bionic” conjures up images of science fiction fantasies. But in fact bionic systems – the joining of engineering and robotics with biology (the human body) – are becoming a reality here and now.


Getting older and less steady on your feet? You need a bionic exoskeleton. Having difficulty climbing those stairs? Try a pair of bionic power trousers. The biggest challenge for making these bionic systems ubiquitous is the huge range of situations we want to use them in, and the great variation in human behaviours and human bodies. At the moment there is simply no one-size-fits-all solution.


So, the key to our bionic future is adaptability: we need to make bionic devices that adapt to our environments and to us. To do this we need to combine three important technologies: sensing, computation and actuation.


Sensing can be achieved by using sensors which directly record brain, nerve and muscle activity, and by using on-body devices such as accelerometers which indirectly measure the movement of our limbs. Computers then link this information with models of human behaviour – often tailored to personal information about how the user moves – and predict the movements that the user is about to initiate. In the final stage, the computer systems use these predictions to divert energy to a set of power actuators. This actuation step provides the needed assistance and support, continually adapting to our changing bodies and the changing environment.


Soft robotics will be more natural than conventional hard bionics. Ociacia


At present, most bionic assist devices are made from rigid materials such as metals and plastics, and are driven by conventional motors and gearboxes. These technologies are well established but their hardness and rigidity can be a great disadvantage. In nature, soft materials such as muscles and skin predominate, and as humans we find comfort in soft materials, such as holding hands or sitting on a sofa.


Soft robotics for bionic bell-bottoms


New “soft robotic” technologies are emerging which have the potential to overcome the limitations of conventional rigid bionics. These systems, as their name suggests, employ soft and compliant materials that work more naturally with the human body. Instead of rigid metals and plastics, they use elastic materials, rubbers and gels. Instead of motors and gearboxes, they’re driven by smart materials that bend, twist and pull when stimulated, for example by electricity.


These smart materials can mimic the contractions of biological muscles, and are often termed “artificial muscles”. With these advances we are now in a position to create radically new adaptive bionic devices for assistance and rehabilitation, including the smart bionic trousers.


Smart trousers will make those stairs easier. Mike Peel, CC BY-SA


The Engineering and Physical Sciences Research Council recently announced £5.3m investment into research targeted at the next generation of adaptive bionic devices. This includes funding for the development of soft robotic smart trousers that will help disabled and elderly people to maintain their mobility and independence.


The goal of the smart trousers project – a major collaboration between the Universities of Bristol, Leeds, Nottingham, Southampton, Strathclyde, Loughborough, and the West of England – is to demonstrate the feasibility of fully autonomous smart clothing. The smart trousers would be able to monitor the wearer’s intentions and give automatic power assistance when needed, for example when getting up from a chair or when climbing stairs.


Of course, this is more than just a technology exercise. The soft robotic clothing will need to be comfortable, easy to put on, hygienic and stylish. These are important considerations that need the direct input of the end users and this project will consult closely, throughout its duration, with the target end users and clinical experts.


The future of smart trousers may lie in even tighter integration with the human body. By implanting sensors under the skin that monitor nerve signals directly, even more precise information about the user’s intentions can be measured. This will enable future devices to have a much more natural relationship with the wearer.


The potential of this approach has been shown in the recent work by the Medical University of Vienna, where three patients with serious hand injuries volunteered to have their hands amputated and replaced with functional prosthetic hands controlled by their own nerve signals. They were then able to perform more sophisticated manipulations with everyday objects then they were before the transplants.


These exciting new technologies look to herald a new era of soft robotic wearable bionic devices for assistance and rehabilitation which work in harmony with, and adapt to, our frail human bodies.


The Conversation

The best video games need not imitate films to be worth a Bafta

Games and films, one award to award them all. Andy Rain/EPA

With the spectacle delivered by increasingly photo-realistic video games with budgets running into tens of millions of pounds on a par with that of the film industry, it seems only right that video games should be offered awards by the same organisation, the Baftas.


On the list of nominees for the British Academy Games Awards this year are many “AAA” titles such as Middle-earth: Shadow of Mordor, Alien: Isolation and Far Cry 4, each demonstrating extraordinarily realistic visual representation involving soundscapes and inspiring technical ambition. These are massive, detailed open worlds to explore, with expansive multi-player options.


Not so novel


Yet there is much that is familiar in these nominations. Franchises such as FIFA football, the Call of Duty first-person shooter and the Forza racer are commercial goldmines that are revisited annually to generate predictable profits. But this discourages risk-taking. Each new iteration of an established title is often little more than a re-skin, a buff-and-polish. This is as much to do with audience expectations of the game they’re getting as it is testament to the development costs required to exploit the technical power of the latest consoles.


Atmosphere? Alien: Isolation has it in spades. The Creative Assembly


Of course such valuable pieces of intellectual property require a safe pair of hands. Game developer studios can’t afford for an instalment to fail, and this commercial need encourages a very conservative approach. This isn’t necessarily a bad thing for the industry, as the profits from established titles can be reinvested in developing new ideas. For example Bungie, the studio behind the hugely successful Halo series, also created Destiny, which expands a typical first-person shooter into a multi-player online game with role-playing elements in an immersive, persistent game universe.


Far Cry 4: good, but more-of-the-same good. Ubisoft


Yet despite the technical accomplishment of next-gen games such as Destiny and the mechwarrior-style Titanfall, many players look for novelty and a different type of challenge. Some games nominated for an award represent very traditional concepts of play. For example, incarnations of classics such as Nintendo’s ever-popular Mario Kart (now up to the eighth instalment), and a simplified version of the retro-themed Minecraft for games consoles illustrate the enduring appeal of old school game mechanics and characters over games that sell themselves on photo-realistic environments.


Still, as in the world of film, it often seems that once again we’ve been seduced by the polish of sequels and derivatives rather than risky new ideas.


Minecraft’s retro appeal has found stella success. AdultsOnlyMinecraft


Indie invasion


So I’m pleased to see much smaller games from indie developers among the shortlist. The explosion of computing power in our pocket via mobile phones and tablets has prompted a new wave of creativity throughout the game industry. With far lower costs to develop games for mobile platforms, the opportunity is there for smaller studios and independent developers (often individuals) to enter the market with interesting, unusual, or downright idiosyncratic games. Big budget games may be technically impressive with their realistic physics engines and lighting, but it’s often the smaller studios with tiny budgets that deliver real innovation.


Some of the nominations this year challenge the orthodoxy in a beautiful way. Lumino City by Camberwell-based State of Play is a great example of a novel approach to graphic style. The painstaking effort to cut and construct a paper-based set provides a truly refreshing environment. It reminds us of the simple pleasures of classroom craft but enhanced in ways we could only dream of as children.


Nominated in four categories, Inkle’s adventure game 80 Days has been lauded for its elegant storytelling and rich interactive narrative. The game isn’t ashamed of its pedestrian pace, using it as a device to enhance the unravelling of the story.


Compelling gameplay doesn’t have to mean breakneck speed and bullet-dodging action; nor, as the regular use of self-deprecating humour in 80 Days demonstrates, do contemporary games need to take themselves so seriously.


Oliver’s journey in 80 Days involves some unlikely characters. Frogwares


The intricacies of the game’s plot – to travel round the world in 80 days, like Phileas Fogg – creates a world that can be explored repeatedly not just to improve on a score, but in order to continue discovering new elements missed on previous run-throughs.


The 25% industry tax breaks for games with a British “cultural value”, finally awarded last year after a seven year legal battle, should encourage more newcomers to the games industry. And as mobile platforms spread more widely, we will hopefully see fewer blockbuster sequels in the future and more small but perfectly formed sensations like Lumino City and 80 days.


Regardless of whether the games enjoy a large or small budget, the Games Baftas should serve to remind us of the enormous versatility, skills and innovation within Britain’s creative industries. Each year UK talent produces some of the world’s most successful video games, which contributes billions to the economy. The British video games industry is a homegrown success story dating back to the 1980s, but which is continually enriched by the range of excellent design and development courses at UK universities today – long may it contiune.


The Conversation

Saturn's moon Enceladus could be another location for life beyond Earth

With geysers bursting through an icy crust, Enceladus is a tiny moon with a big personality. Hsiang-Wen Hsu et al/Nature, Author provided

The Cassini mission that has investigated Saturn since 2004 has revealed much about the giant planet and its many moons. Perhaps most tantalising is the discovery that the moon Enceladus is the source of strong geysers ejecting plumes of water and ice.


A new study of Cassini data published in Nature by Hsiang-Wen Hsu and colleagues reveals these plumes are laced with grains of sand. This indicates that hydrothermal activity may be at work in Enceladus' sub-surface ocean, and propels this tiny moon into the extremely exclusive club of locations that could harbour life.


The club’s only current member is Earth, of course – although it’s very possible that Europa, one of Jupiter’s moons, is, like Enceladus, also a candidate. What they have in common is that they host liquid oceans of salty water that exists in contact with a rocky, silicate seabed from which the oceans can absorb complex minerals and elements.


A bit of a geyser


With a diameter of just 500km Enceladus is nevertheless the sixth largest of Saturn’s more than 60 moons, orbiting at a distance of just two planet-widths. Cassini has shown that Enceladus is the source of huge geysers of neutral water-rich gas and ice grains erupting at a rate of 100-300kg per second. This makes Enceladus the second most active object, after Jupiter’s moon Io which ejects one tonne per second of sulphur-rich material.


How the plumes are formed, from beneath Enceladus' surface. NASA


Gravity measurements have shown that there is at least a local and possibly a global ocean under Enceladus’ icy crust, and some of the emitted grains are rich in sodium salt, which indicates the presence of a salty ocean. Now we also discover that some are silicate-rich, and analysis shows that these may have been produced close to hydrothermal vents at temperatures above 90°C. This raises the interesting comparison with hydrothermal vents on Earth, which may have played a role in the origin of life on our planet.


The recipe for life


For life as we know it to exist, four key ingredients are important: liquid water; the right chemistry involving the elements carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur; a source of heat; and enough time for life to develop. While we know these conditions exist on Earth, planetary research throughout the solar system shows that it may exist on other objects too, and the details from this paper pushes Enceladus towards the top of the list.


We know liquid water oceans exist on several objects in our solar system. These include Earth with its surface oceans, and Jupiter’s moons Europa, Ganymede and Callisto, and Saturn’s moons Titan and Enceladus where the oceans are below the surface. Water has also played a vital role in Mars’ history: Geronimo Villanueva and colleagues recently showed that there may have been enough water on Mars to cover the planet in an ocean 137 metres deep around 3.8 billion years ago –- about the time when life was starting on Earth.


The view from Cassini towards the geyser region of Enceladus. NASA


There may also be water on the dwarf planets Ceres and Pluto, Neptune’s moon Triton, and several other objects in the solar system – but only further investigation will tell. Two other objects have lakes and oceans, but not of water. Titan has lakes of methane and ethane, for example – the only extraterrestrial object we know of with liquid on the surface – and volcanic Io has a subsurface ocean of liquid magma.


A shortlist for extraterrestrial life


So where are the best places to look for life in our solar system? The short list now seems to be Mars, Europa and Enceladus. At Mars the most likely time for life to have existed is 3.8 billion years ago when water was present, so the ESA-Russia ExoMars rover due for launch in 2018 will focus on drilling 2m below the present surface’s harsh oxidising and radiation-rich environment to search for buried evidence from the past. It carries our PanCam instrument which will provide context for the mission.


As for right now, Mars may be a less good candidate for life. Following a catastrophic collision about 3.8 billion years ago the planet underwent massive climate change, volcanic activity stopped, and the planet’s magnetic field disappeared. But the recent confirmation by Curiosity of the presence of methane is tantalising. At Europa, ESA’s JUICE mission and the proposed NASA Europa Clipper may bring more clues in the 2030s, but further missions to Enceladus have yet to make it past the proposal stage.


Nevertheless, this leaves Europa and Enceladus as prime sites where conditions may be suitable for life to exist now – but who knows which other solar system objects could be the next to join the club.


The Conversation

What will we find next inside the Large Hadron Collider?

What lies within? Maximilien Brice/CERN, CC BY-NC

The Large Hadron Collider, the world’s largest scientific experiment, is due to restart this month after two years of downtime for maintenance and upgrading. There’s no doubt that having played its role in the discovery of the Higgs boson in 2012, what the media christened the “God particle”, expectations for what the 27km particle accelerator at CERN could achieve this time have certainly been set high.


The Higgs boson is a possible explanation for the origin of mass, something predicted in 1964 by Peter Higgs and several other physicists, and the discovery of which led to the award of a Nobel Prize for physics for Higgs and François Englert in 2013.


So why did it take so long to discover it? As Einstein showed in his mass-energy equivalence (E=MC2), the mass of a particle is a measure of its energy content. If a particle is more massive, it has a greater energy content, and conversely to create a massive particle requires a great deal of energy. So simply put, it wasn’t until the Large Hadron Collider (LHC) was capable of colliding beams of protons with sufficient energy that the Higgs Boson could be created with its mass of 126 billion electron volts (gigaelectronvolts, or GeV). In particle physics it is usual to give masses in terms of energy, and while 126GeV is equivalent to only 2.24x1025kg, this mass is about 127 times larger than a single proton.


So the intention is that following a two-year upgrade the LHC’s new, more powerful electromagnets will be sufficient to accelerate two beams of protons to 6.5 trillion electron volts (teraelectronvolts, or TeV), increasing the potential collision energy from 8TeV in 2012 to 13TeV. And with greater collision energy comes the possibility of creating and detecting new particles of even greater mass. The expectation is that the LHC’s experiments could uncover new particles known as Z particles, new Higgs bosons, and even particles of dark matter.


A map of subatomic particles, known and hypothesised. MissMJ, CC BY-SA


From Higgs to Z


Discovered at CERN in 1983, the Z particle 0 removed for clarity, sure it doesnt matter is a force carrier – a particle that carries one of the four fundamental forces of nature: the gravitational, electromagnetic, strong and weak forces strong/weak forces are fundamental forces? arent' they just a measure? - no one works at the atomic level, one subatomic. everything has silly names these days (quarks are top bottom charm fast slow, etc). The Z particle carries the weak force, which is implicated in subatomic reactions. A related, theorised particle that could be next to be discovered is the Z prime particle, or Z'. This would help our understanding of gravitons, the carriers of the gravitational force that are theorised but have not yet been detected.


Taking the constituents of the universe as a whole, we have a good understanding of about 5% of it. The remaining 95% is made up of about 68% dark energy and 27% dark matter. With a little over 84% of the universe’s mass being dark – not detectable by any known means – if the LHC can in some way shed some light on the nature of this matter it will move our understanding of the universe forward.


With an upgraded LHC able to provide higher collision energies and the possibility of creating new particles – whether those currently theorised or not – it will have a significant impact on our fundamental understanding of the laws of nature and the accepted model that is used to try and explain them.


Some may point to the cost of the LHC upgrade, estimated at around £70m, as a cost beyond the public purse in these cash-strapped times of austerity. But the possibilities for what it can add to our understanding of the world cannot be ignored either, nor the benefits they might have in other areas, for example medical imaging. Considering how regularly sums far larger than £70m of taxpayers' money are squandered, CERN’s role as a global educational tool for physicists, mathematicians and engineers must be considered excellent value for money.


The Conversation

Why are cacti so juicy? The secret strategy of succulents

Blooming marvellous: cacti are among the few plant species that can thrive in the desert Alan Levine/Flickr, CC BY-SA

Sunlight, harnessed by plants in the process of photosynthesis, powers almost all life on earth. Special adaptations allow certain plants to store up a battery of carbon dioxide overnight for use in photosynthesis during the day, giving them a juicy advantage in dry desert conditions.


The processes that constitute life – such as growth, repair, movement and reproduction – all require an energy source. The immediate source of this energy for many living things is chemical energy.


High-energy carbon-based molecules, such as sugars and fats, are broken down to power the processes of life. These high-energy molecules don’t naturally occur in the environment. Work-shy and dishonest organisms, such as humans, rely on stealing high energy molecules from other organisms by eating them. Ultimately, however, more high energy molecules are required to replace those broken down.


While sugars and fats sadly don’t rain down from space, energy-rich photons (the next best thing) do, in the form of sunlight. More responsible organisms than us, such as plants and algae, perform photosynthesis. This process uses energy from sunlight to regenerate high energy molecules from their breakdown waste product, carbon dioxide (CO2), which is constantly released into the atmosphere by all living things.


In the most common form of photosynthesis, CO2 is taken up into leaves during the day via tiny pores in the plant surface. It is then attached, or “fixed”, straight onto a sugar molecule using energy from sunlight, to be used as a source of chemical energy – either by the plant, or by the animal that eats it.


Tiny pores let carbon dioxide into the leaf – but also allow oxygen in and water out Photohound


But acquiring CO2 from the atmosphere can be problematic in some situations. Opening the pores on the plant surface lets CO2 in, but also lets oxygen in and water out. Water loss is a problem in dry environments – particularly during the day, which is when CO2 is required for photosynthesis.


Additionally, in hot environments, the plant is less able to discriminate between oxygen and CO2 and can actually end up attaching oxygen to the sugar molecule. Once an oxygen molecule is fixed to a sugar, it must be prised off again at significant energetic cost, reducing the net energy that plants can acquire from photosynthesis.


Carbon dioxide batteries for efficiency


Several groups of plants have evolved that do not directly fix atmospheric CO2 to make sugars, but attach CO2 onto other molecules which can be stored, transported and broken down to release CO2 again, like a battery. This avoids the problems of water loss and accidental oxygen fixation.


Two alternative strategies have evolved to make use of this ability: C4 photosynthesis, which manipulates the concentration of CO2 in space, and CAM photosynthesis, which manipulates the concentration in time.


C4 photosynthesis is performed by 7,600 species, most of them grasses, including maize and sorghum. It has evolved independently at least 60 times, yet is present in less than 0.5% of plant species. Although highly competitive in hot environments, the energetic costs associated with carbon storage mean that plants carrying out conventional photosynthesis have the edge at lower temperatures.


C4 photosynthesis uses a special enzyme to fix atmospheric CO2 onto an acid. This enzyme is much better at discriminating between CO2 and oxygen than the classic enzyme used in traditional photosynthesis. The acid is transported deep inside the plant, where concentrations of oxygen are much lower, and the CO2 is re-released. In this low-oxygen environment, the plant makes fewer oxygen-fixing mistakes, increasing the efficiency of photosynthesis. There is an energetic cost to this roundabout way of doing photosynthesis, but this is more than offset by the decrease in costly oxygen fixation in hot environments.


Cacti and pineapple plants use CAM photosynthesis to stay juicy. hiyori13/Flickr, CC BY-SA


The other alternative kind of photosynthesis is CAM, or Crassulacean Acid Metabolism, which predates C4 photosynthesis by at least 150 million years. This was first discovered in the Crassula family of plants but has evolved independently in many lineages of plants, totalling over 9,000 species.


Like C4 plants, CAM also stores CO2 in an acid, but it performs this reaction at night, and rather than transporting the acid molecules to a different part of the plant, it simply stores them in the vacuole – the storage area at the heart of each plant cell. During the day, when the light required for photosynthesis is available, the plant doesn’t need to open its pores: it has a packed lunch already stored in its cells. This allows the plant to perform photosynthesis without opening its pores during the day, massively reducing the amount of water lost.


This is how CAM plants such as cacti and pineapples can remain succulent and watery despite the hot environments they grow in. In wetter or cooler environments, however, the problems solved by CAM and C4 photosynthesis aren’t as severe – and the energetic cost of storing and re-releasing CO2 means the plants are only competitive with their traditionally photosynthesising cousins in hot or dry environments.


Perhaps the very last place, therefore, that one might expect to find CAM plants is underwater, a pretty wet environment by all accounts. It was with some surprise therefore that CAM was first reported in the lake plant Isoetes followed by discoveries in four other genera of aquatic plants.


Tiny aquatic plants of the genus Isoetes carry out CAM to concentrate carbon dioxide in the underwater world US Fish & Wildlife Service


Despite their very different environments, plants in lakes and deserts ultimately share the same problem –- the difficulty of acquiring CO2. While a lot of CO2 can be dissolved in water, it diffuses far more slowly than in air, so the water around a plant can become depleted of CO2. Aquatic plants have evolved CAM photosynthesis so that they can continue taking up CO2 at night, using it to supplement that which they can acquire during the day.


In addition to research aiming to introduce C4 photosynthesis into rice, there has been significant interest in modifying crop plants to perform CAM photosynthesis so they can better survive droughts caused by climate change.


The Conversation

Monday, March 9, 2015

Goodbye P value: is it time to let go of one of science's most fundamental measures?

Clinical trials rely on statistics to show whether drugs are more effective than placebo pills. But how can we be certain? Semmick Photo/Shutterstock

How should scientists interpret their data? Emerging from their labs after days, weeks, months, even years spent measuring and recording, how do researchers draw conclusions about the results of their experiments? Statistical methods are widely used but our recent research in Nature Methods reveals that one of the classic science statistics, the P value, may not be as reliable as we like to think.


Scientists like numbers, because they can be compared with other numbers. And often these comparisons are made with statistical analyses, to formalise the process. The broad idea behind all statistical analyses is that they allow the researcher to make somewhat objective assessments of the results of their experiments.


Which drug is more effective?


Scientists often conduct experiments to investigate whether there is a difference between two conditions: do people get better more quickly after taking the blue pill (condition one) or the red pill (condition two)? The most common method for assessing if the pills differ in their effectiveness is to undertake statistical analysis of where some patients were given the blue pill and some the red, and from this determine whether there is strong evidence that one colour is more effective than the other.


To assess experimental results, scientists very often use a “P value” (P is for probability). This is used to show how convincing these results are: if the P value is small, they think that the findings are real and not just a fluke. In our pill example, if P is small this is considered good evidence that there is a difference in effectiveness of the two colours of pill.


Although P is never proof that there is a difference – scientific studies never prove things, they only provide a degree of evidence for them – studies with low P values are thought to be convincing, and so are not often repeated to be sure the results are correct. This might seem reasonable because there is limited money and time in science – results from a study that seem very clear perhaps do not warrant double-checking when there are new discoveries out there to be made.


P values are fickle friends


However, we have used simple models to show that the P value often varies dramatically if a study is replicated. Our models depict a simple scenario. Samples have been measured from two conditions. A statistical test called a t-test is conducted to investigate whether there is good evidence that the conditions are different, and the test result is interpreted by the generation of a P value.


The two conditions in our scenario are indeed somewhat different and so we might expect a reasonable sample size to uncover this difference. That is, a reasonable sample size will return a low P value associated with the t-test. However, when we repeat the model experiment many times over, we find that the P value varies dramatically each time.


If your friend has invited you round for dinner next week but in the preceding days keeps contacting you and giving dramatically differing arrival times, you will soon conclude you have very little idea of what time dinner will actually be. Similarly, if P varies considerably each time an experiment is conducted, this makes the P value unreliable, and a poor measure of how strong the evidence is from a single run of that experiment.


The implication is huge for data analysis –- a low P value returned from a study is likely to have as much to do with luck as it has to do with the presence of an important pattern in the data, and in turn a re-run of the experiment might well result in a very different P value. Therefore, a low P value for a single experiment cannot be taken as good evidence that there is a difference between the conditions.


This weakness could well explain why famous scientific findings from the past, central to the foundations of many disciplines, are not being confirmed now that the original studies are finally being re-examined.


These include a lack of reproducibility in cancer research, as well as the apparent loss of the phenomenon called “verbal over-shadowing” whereby people shown a face and asked to describe it are less likely to recognise the face later on than if they had simply looked at it.


Late again! Like an unreliable friend, the P value doesn’t deliver the goods every time. Sfio Cracho/Shutterstock


So why is the P value so variable, so fickle? Unfortunately it seems that some degree of variability between the samples for each occurrence of an experiment creates an unstable P value.


Moving on


So if not the P value, what should we use to analyse and interpret our data? We argue for a fundamental shift in thinking away from asking the question “is there a difference?” and towards asking “how big is the difference?”. After all, scientists rarely want to know simply whether there is a difference between conditions.


There is always a difference, even if extremely small. It is more pertinent to ask whether the difference is big enough to be of interest, to be of importance. If the effectiveness of the red pill is just 0.01% greater than that of the blue pill, there is a difference between them but it isn’t noteworthy – in practice one pill colour is as good as the other.


The P value can be ditched and scientists can focus instead on how big the difference is between the conditions according to their experiment. They can also provide simple-to-calculate values on how precise that difference is likely to be when generalised beyond the laboratory.


Thus once data collection has finished, scientists should focus on estimating how big the difference is in the effectiveness of the blue and red pills, and how precise this estimate is likely to be. Researchers already know about these simple concepts – effect sizes and confidence intervals – they just need to start emphasising them, and let the P value become a thing of the past.


Unfortunately, while a smattering of journals have now started to outlaw the P value in recognition of some of its failings, recently at least one journal has also banned the use of the confidence interval, apparently because its precise statistical definition risks it being over-interpreted and misunderstood.


A reasonable counter to this point of view is that confidence intervals are a valuable tool for estimating the margin of error around our findings – they are a crucial measure when translating our sample of data collected in the laboratory into an understanding of real world scenarios, where results really matter.


The Conversation

Sneaky Techies Are Playing Dress Up To Swipe Secret Legal Files

Imagine a bustling law firm in the heart of a skyscraper-filled city. The air is thick with the scent of expensive espresso and the frantic...