People learn when they discover ideas on their own.
By Daniel Bor in neuroimaging Over this week, there has been a striking debate in the blogosphere and on Twitter concerning the flaws in many published neuroimaging studies. His partial explanation was that this was in a different age, with more lax conventions and admittedly he was only a minor author on the paper himself.
Late Tuesday night, Neurocritic posted a provocative blog article in response to this, asking the question: Two key issues quickly surfaced: I thought it might help in this discussion to explain one of the main statistical issues that this debate is pinned on, that of corrected versus uncorrected statistics, and how this applies to brain-scanning.
And if many published imaging papers are so flawed, I want to try to explain how the literature became so sloppy. Just to flag up that this blog is addressing two audiences. I wanted to explain the context of the debate to a general audience, which occurs in the next two sections, and suggest how they can assess neuroimaging stories in the light of this in the last small section.
The middle sections, although hopefully understandable and maybe even of some interest to all, is directed more at fellow scientists. So what are corrected and uncorrected statistics? Imagine that you are running some experiment, say, to see if corporate bankers have lower empathy than the normal population, by giving them and a control group an empathy questionnaire.
How can you tell whether this is just some random result, or that bankers really do have lower empathy? This is the point where statistical testing enters the frame.
Classically, a statistical test will churn out a probability that you would have got the same result, just by chance. All well and good, but what if you also tested your control group against politicians, estate agents, CEOs and so on?
His mojo must be building! So he tries again, and again and again. Then, as if by magic, on the 20th attempt, he gets all 4 heads. Joe Superstitious proudly concludes that he is in fact very skilled at telekinesis, puts the coin in his pocket and saunters off.
Joe Superstitious was obviously flawed in his thinking, but the reason is actually because he was using uncorrected statistics, just as the empathy study would have been if it concluded that bankers are less empathic than normal people.
If you do multiple tests, you normally have to apply some mathematical correction to take account of how many tests you ran. How does this apply to brainscanning? Moving on to neuroimaging, the data is far more complex and inordinately larger, but in essence exactly the same very common statistical test one might have used for the empathy study, a t-test, is also used here in the vast majority of studies.
So there is a vast problem of some of these voxels to be classed as significantly active, just by chance, unless you are careful to apply some kind of correction for the number of tests you ran.Observing Mitosis Lab Background: In a growing plant root, the cells at the tip of the root are constantly dividing to allow the root to grow.
Because each cell divides independently of the others, a root tip contains cells at different stages of the cell cycle. This makes a root tip an excellent tissue to study the.
Course Description: This course is an accelerated, lab-oriented introduction to Biology, which emphasizes cell structure / function, molecular basis of heredity, biological evolution, interdependence of organisms, matter / energy / organization of living systems, and behavior / regulation of organisms.
Feb 15, · 50 Famous People Who Were Teachers When students talk about what they'd like to major in when they go to college, I always advise them to pick something they are passionate about.
After all, they will be doing it for a long time. The ACT test is a curriculum-based education and career planning tool for high school students that assesses the mastery of college readiness standards. It looks like scientists and philosophers might have made consciousness far more mysterious than it needs to be.
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