Random or fixed effects?/ Efectos fijos o efectos aleatorios?

One of the decisions to be taken when performing a systematic review is whether to choose a random or fixed effects model. Very briefly, a fixed effects model is chosen if the studies in the metaanalisys are homogeneous, and random effects model is preferred otherwise. This video illustrates the question:

http://www.youtube.com/watch?v=laviboNorXk

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Una de las decisiones que hay que tomar cuando se lleva a cabo una revisión sistemática es si se debe escoger un modelo de efectos fijos o de efectos aleatorios. De manera muy resumida, se escogen efectos fijos si los estudios incluidos en el metaanálisis son homogéneos, y efectos aleatorios en caso contrario. Este vídeo ilustra la cuestión.

http://www.youtube.com/watch?v=laviboNorXk

Webinar on Revman (Cochrane) / Webinario sobre Revman (Cochrane)

Revman is the free program by the Cochrane Collaboration to perform systematic reviews. This is a 2012 Youtube tutorial from the Canadian Cochrane Network, by John MacDonald.

Revman tutorial (click here)

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Revman es el programa gratuito de la Cochrane Collaboration para la realización de revisiones sistemáticas. Este es un vídeo tutorial de Youtube, de la Canadian Cochrane Network, por John MacDonald.

Revman tutorial (click here)

Data Transparency

An interesting link shared by Prof. Amanda Burls (University of Oxford), to a youtube vídeo on tge Workshop on Clinical Trial Data and Transparency, from the European Medicines Agency.
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Interesante enlace compartido por la profesora Amanda Burls (University of Oxford), de un vídeo de youtube sobre el Taller sobre Datos y Transparencia de Ensayos Clínicos, de la Agencia Europea de Medicinas.

More on Bayesian inference and the Bayes Theorem/ Más sobre Inferencia Bayesiana y el teorema de Bayes

 Sharon Bertsch McGrayne makes a lovely presentation (click here) on Reverend Thomas Bayes and his theorem at the The Singularity Summit held in New York in 2011.

Allen Downey features a lesson on Bayesian Inference made as simple as possible. This is his blog.

The MIT offers a class on Bayesian inference here. The second part is offered here.

This is the article on Bayes´ Theorem at the Stanford Enciclopaedia of Philosophy
http://plato.stanford.edu/entries/bayes-theorem/
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GAPMINDER

GAPMINDER is a beautiful tool for statistical data display, created by Ola Rosling, Anna Rosling Rönnlund and Hans Rosling. The latter is a professor at the Karolinska Instutet, and we have had some very interesting presentations by him in previous threads of the blog.

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 GAPMINDERes una bella herramienta para la representación de datos estadísticos, creada por Ola Rosling, Anna Rosling Rönnlund y Hans Rosling.
Este último es porfesor del Karolinska Instutet y ya hemos visto algún vídeo muy interesante realizado por él en entradas previas del blog.

How can Healthcare learn from aviation safety?

National Patient Safety Foundation 2012 meeting, by Jeff Skiles, First Officer of US Airways Flight 1549, and Rollin "Terry" Fairbanks, physician and healthcare safety expert.

https://www.youtube.com/watch?v=kaydVvH7S4E

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 ¿Cómo puede aprender la sanidad de la seguridad aeroespacial? 

Reunión de la National Patient Safety Foundation en 2012, con by Jeff Skiles, Primer Oficial del vuelo US Airways 549, y Rollin "Terry" Fairbanks, médico y experto en seguridad sanitaria.

https://www.youtube.com/watch?v=kaydVvH7S4E

Patient Safety Checklists

This is a link to a youtube video where Dr. Peter Pronovost discusses the science of improving patient safety. Dr. Pronovost is an anesthesiologist and Intensive Care physician, and a professor at Johns Hopkins. He has made an outstanding contribution to Medicine with a safety checklist for Intensive Care Units.

https://www.youtube.com/watch?v=jxxkz-WeV_w

More on him at this article from The Lancet:

http://download.thelancet.com/pdfs/journals/lancet/PIIS0140673609614392.pdf?id=e16241398b8eb460:-6247bb0e:13b5fe0ac55:-39c1354526563123

About his checklist:
http://ccforum.com/content/13/6/210/
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He aqui un enlace a un vídeo de youtube donde el Dr. Peter Pronovost habla sobre la ciencia de mejorar la seguridad de los pacientes. El Dr. Pronovost es anestesiólogo y especialista en Mecinia Intensiva, y profesor en Johns Hopkins. Su "checklist" para Unidades de Cuidados Intensivos ha sido una contribución sobresaliente a la medicina.

https://www.youtube.com/watch?v=jxxkz-WeV_w

Más sobre él en este artículo del Lancet:

http://download.thelancet.com/pdfs/journals/lancet/PIIS0140673609614392.pdf?id=e16241398b8eb460:-6247bb0e:13b5fe0ac55:-39c1354526563123

Sobre su "checklist":
http://ccforum.com/content/13/6/210/

Journal of Public Health Suboptimal Results

The germ of a new journal:

http://jphsr.blogspot.com.es/

This link redirects to a blog that has the intention to be the germ of a new journal to share information on unwanted events on Public Health. Brainstorming is wellcome to help outline its structure and content. Anyone is invited.

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El germen de una nueva publicación científica:

http://jphsr.blogspot.com.es/

Este enlace dirige hacia un blog que tiene la intención de servir de germen para una nueva publicación para compartir información sobre sucesos no deseados en Salud Pública. Se agradece tormenta de ideas para ayudar a delimitar su estructura y contenido. Todo el mundo está invitado.

How to be creative? An interesting video by Monty Python´s actor and former Cambridge student John Cleese:

https://www.youtube.com/watch?v=VShmtsLhkQg

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¿Cómo ser creativo? Un vídeo muy interesante del actor de Monty Python y antiguo alumno de Cambridge, John Cleese:

https://www.youtube.com/watch?v=VShmtsLhkQg

Washing Machine

I strongly recommend this amusing video by professor Hans Rosling, a leding authority on Global Health at  Karolinska Institute (yes, the people that give the Nobel Prize).
Subject of the talk: washing machines. No, I am not joking! You should see it...

http://www.ted.com/talks/hans_rosling_and_the_magic_washing_machine.html

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Recomiendo encarecidamente este vídeo del porfesor Hans Rosling, una autoridad en Salud Global del Instituto Karolinska (sí, la gente que otorga los premios Nobel).

Tema de la charla: lavadoras. No, no estoy de broma. Deberíais verlo...

http://www.ted.com/talks/hans_rosling_and_the_magic_washing_machine.html

This is the web page of Nancy Sheppard, a medical anthropologist at the University of Berkeley. She boosted research on human organ traffic and its ethical implications.

http://anthropology.berkeley.edu/users/nancy-scheper-hughes

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Esta es la página web de Nancy Sheppard, antropóloga médica de la universidad de Berkeley. Es quien ha impulsado la investigación sobre el tráfico de órganos en el mundo.

http://anthropology.berkeley.edu/users/nancy-scheper-hughes

Tynsley Randolph Harrison - Harrison´s Principles of Internal Medicine

Tynsley Randolph Harrison was the editor of the first fifth editions of Harrison´s Principles of Internal Medicine, maybe the best known and most consulted teatise on Internal Medicine in the world.

He attended the University of Michigan and the Johns Hopkins School of Medicine. He did his Internship in the Peter Bent Brigham Hospital (later to be the Brigham and Women´s Hospital at Boston), and carried out his residency in Johns Hopkins and Vanderbilt.
He was a professor at the University of Alabama School of Medicine in Birmingham, Alabama for many years.

More of Him here:

http://en.wikipedia.org/wiki/Tinsley_Randolph_Harrison

Interesting explanation of the Higgs Boson using sugar!

This BBC video explains the Higgs field and the  Higgs Boson using ping pong balls and sugar! Must be easy, then...

http://www.youtube.com/watch?v=ZzQpeqE_wLg&feature=related

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¡Este vídeo de la BBC explica el campo de Higgs y el bosón de Higgs utilizando pelotas de ping-pong y azúcar! Debe ser fácil, entonces...
http://www.youtube.com/watch?v=ZzQpeqE_wLg&feature=related

Statistics to look for the Higgs Boson

This is a clear explanation from a highly reliable source (the Fermilab) of how Statistics are used to search for subatomic particles.

http://www.youtube.com/watch?v=73JeQ2RZnwc

And this is a simple and staightforward explanation of what the Higgs Boson is:
http://www.youtube.com/watch?v=1SihuUElE48


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He aquí una explicación clara y procedente de una fuente altamente fiable (el Fermilab) de como la Estadística se usa en la búsqueda de partículas subatómicas.

http://www.youtube.com/watch?v=73JeQ2RZnwc

Y esta es una explicación simple y directa de qué es el Bosón de Higgs:

http://www.youtube.com/watch?v=1SihuUElE48

WHO safety checklist

Tutorial video with intructions on how to perform the WHO checklist.

http://www.youtube.com/watch?v=CsNpfMldtyk

Another one on how NOT to perform it:

http://www.youtube.com/watch?v=REyers2AAeI

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Vídeo tutorial sobre como realizar la lista de comprobación de la OMS sobre seguridad en cirugía:

http://www.youtube.com/watch?v=CsNpfMldtyk


Otro vídeo sobre como NO realizar la comprobación:

 http://www.youtube.com/watch?v=REyers2AAeI

Whooping cough // Tos ferina

This is a mnemonic drawing to remember the main clinical feature of whooping cough: paroxysmal crisis of violent cough. In Spanis it is called "tos ferina", (Coughing like a beast)

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Dibujo mnemotécnico para recordar la característica fundamental de la TOS FERINA: Toser como una fiera. Crisis paroxísticas violentas de tos.

More on Homeopathy

http://jme.bmj.com/content/36/3/130.full

An editorial of the Journal of Medical Ethics titled Homeopathy is where the harm is: five unethical effects of funding unscientific ‘remedies’.

Homeopathy/ Homeopatía

First of all I must tell you that I am against the use of Homeopathy and its inclusion in the public Health system. I have gatherred enough information to confidently say that it does not work beyond the placebo effect, and that it cannot work (it is not possible from a scientific point of view). I am not against Hopeopathic doctors. I give them the benefit of the doubt and assume that they have no bad intention, but instead are very badly missinformed.
I have found out that this is the Homeopathy Awareness week. But, hold on, this is not an official campaign to warn public against the lack of effectiveness and quackery of Homeopathy! It actually is a marketing manouever to try to convince consumers to buy Homeopathy.
For this reason I am writing this article. I think it is necessary to be aware of what homeopathy claims to be, and what it really is.

FIRST. Homeopathy claims that sympthoms of a disease can be treated with a very tiny quantity of a drug that, in higher doses, will give those same unwanted sympthoms.

SECOND. According to Hopeopathy, the more diluted the drug, the bigger the effect (i.e. benefit).

THIRD. In Homeopathy drugs are diluted over and over, until you get the bottle or pill or whatever treatment the patient ultimately gets. Having diluted the drug so many times, it is IMPOSSIBLE to find a single molecule of the original drug in the treatment that the patient will have. (This has been proven and most homeopaths accept this fact).

FOURTH. As a means to figure out an explanation for the supposed activity of an homeopathic treatment, homeopaths have invented the ackward and totally nonsense theory that "Water has memory".

FIFTH. When properly tested, Homeopaty has not proven to be more effective than placebo.

You can find some interesting links on homeopathy further down:

http://www.youtube.com/watch?v=_ZhmG97lYog
A BBC Horizon doccumentary about homeopathy. Very informative.

http://www.youtube.com/watch?v=BWE1tH93G9U
James Randi explains how Hoeopathy works

http://www.elmundo.es/blogs/elmundo/desde_el_mas_alla/2012/06/18/homeopatia-gruyere.html
A link to a spanish newspaper science section.

http://www.badscience.net/2007/11/the-lancet-benefits-and-risks-of-homoeopathy/
An article by Dr. Ben Goldacre

http://www.1023.org.uk/why-you-cant-trust-homeopathy.php


http://skepticbarista.wordpress.com/2012/06/14/homeopathy-awareness-week-are-you-aware/

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Primero de todo he de decir que estoy en contra del uso de la homeopatía y su inclusión en el sistema público de salud. He recopilado suficiente información para afirmar con confianza que no fuciona más allá del efecto placebo, y que no puede funcionar (no es posible desde un punto de vista científico). No tengo nada en contra de los médicos homeópatas. Les ofrezco el beneficio de la duda y pienso que no tiene mala intención, simplemente están mal informados.
Me he enterado de que esta es la Semana De Concienciación sobre Homeopatía. Pero cuidado! No se trata de una campaña oficial para advertir sobre los peligros del charlatanerismo, sino que es una maniobra de marketing para convencer al público de que consuma homeopatía.
Por ese motivo he escrito este artículo. Para avisar al público sobre lo que la Homeopatía dice ser y sobre lo que realmente es.

PRIMERO. La homeopatía afirma que un síntoma puede tratarse con cantidades muy pequeñas de una substancia que, en dosis más altas produce los mismos síntomas que se quieren tratar (Curioso!!).

SEGUNDO. Según la homeopatía, cuanto más diluida esté la substancia, mayor será su efecto (es decir, su pretendido beneficio).

TERCERO. En homeopatía las substancias se diluyen una y otra vez hasta obtener el tratamiento que se le administra al paciente. Habiendo diluido la substancia tantas veces es VIRTUALMENTE IMPOSIBLE encontrar una sola molécula de la substancia activa. (Esto se ha probado científicamente y la mayor parte de homeópatas lo aceptan).

CUARTO. Para obviar este problema, los homeópatas han inventado la fabulosa (y totalmente sin sentido) explicación  de que el agua "tiene memoria".

QUINTO. Cuando se estudia apropiadamente, la homeopatía NO es más efectiva que el placebo.

Online Bioethics courses // Cursos Online sobre Bioética

Links to Online Bioethics courses. Most of them are free. Although it has a 200 GBP fee, I especially recommend the University of Oxford “Bioethics for Beginners” (SEE BELOW).

Enlaces a cursos sobre Bioética en Internet. La mayoría son gratis. Aunque tiene un precio de 200 libras esterlinas, recomiendo especialmente el curso de la Universidad de Oxford “Bioethics for Begginers” (ver más abajo).

Johns Hopkins School of Public Health

Ethics of Human Subject Research

http://ocw.jhsph.edu/courses/EthicsHumanSubjectResearch/

University of Oxford

Bioethics for Beginners

http://www.conted.ox.ac.uk/courses/details.php?course_subject=Philosophy&id=V500-12&coursetype=100

Massachusetts Institute of Technology (MIT)

Bioethics

http://ocw.mit.edu/courses/linguistics-and-philosophy/24-06j-bioethics-spring-2009/

National Human Genome Research Institute

Health Professional Education

http://www.genome.gov/17517037#al-3

North Carolina State University

Bio-medical Ethics

http://distance.ncsu.edu/courses/course-details.php?id=PHI:325::601:FALL:2012

Cleveland Clinic

Office of Civic Education Initiatives

(Course for high school students)

http://www.clevelandclinic.org/civiceducation/realworld/bioethics.asp

Fisterra

(In Spanish)

http://www.fisterra.com/formacion/bioetica/

Dr Tom Kerns

North Seattle Community College

Introduction to Bioethics

http://www.bioethicscourse.info/

American College of Dentists

Courses Online Dental Ethics (CODE)

https://www.dentalethics.org/

Washington State University

Bioethics- Graduate Certificate

http://online.wsu.edu/future_students/dc_bioethics_grad.aspx

World Medical Association

Ethics Course

http://www.wma.net/en/70education/10onlinecourses/30ethics/index.html

Guidelines for patient safety // Directrices para la seguridad del paciente

Below you have the links to the guidelines for patient safety from the World Health Organization, the Joint Commission, and the International Medication Safety Network. The last link has some video resources from the FDA.

WHO guidelines for adverse event reporting and learning systems:
http://www.who.int/patientsafety/events/05/Reporting_Guidelines.pdf

WHO GUIDELINES FOR SAFE SURGERY:
http://gawande.com/documents/WHOGuidelinesforSafeSurgery.pdf

International Medication Safety Network
http://www.intmedsafe.net/contents/Resources.aspx

Joint Commission:
http://www.jcrinc.com/

Medication-related FDA Patient Safety videos provided in cooperation with ISMP
http://www.ismp.org/Tools/fdavideos.asp


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Más abajo tenéis los enlaces de las directrices y recursos sobre seguridad del paciente de la OMS, la Joint Commission, y la International Medication Safety Network. El último enlace contiene vídeos sobre seguridad del paciente de la FDA.


Guía de la OMS para la notificación de reacciones adversas y sistemas de aprendizaje:
http://www.who.int/patientsafety/events/05/Reporting_Guidelines.pdf

Guía de la OMS para SEGURIDAD EN LA CIRUGÍA:
http://gawande.com/documents/WHOGuidelinesforSafeSurgery.pdf

Joint Commission:
http://www.jcrinc.com/

International Medication Safety Network
http://www.intmedsafe.net/contents/Resources.aspx

Vídeos sobre seguridad del paciente de la FDA en cooperación con la ISMP
http://www.ismp.org/Tools/fdavideos.asp

Learning material for Cochrane reviewers // Material didáctico para revisores de Cochrane

This is a link with leanring material for those intending to do (or already engaged in) a systematic review for the Cochrane library. You can consult it on screen or print the 196 page PDF file.

http://www.cochrane-net.org/openlearning/


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Este es un enlace con material didáctico para los interesados en realizar (o ya involucrados en) una revisión sistemática para la Cochrane. Puede consultarse en pantalla o imprimirse un documento PDF de 196 páginas.

http://www.cochrane-net.org/openlearning/

RevMan tutorial in Youtube // Tutorial RevMan en Youtube

You can see a tutorial of the RevMan (the program used to do the Cochrane reviews) in this links:

Part 1
http://www.youtube.com/watch?v=P6susM9BT0A

Part 2
http://www.youtube.com/watch?v=VqcNJ0UkGhg&feature=relmfu

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Podeis ver un tutorial sobre RevMan (el programa que se utiliza para realizar las revisiones sistemáticas de Cochrane) en estos enlaces:

Parte 1
http://www.youtube.com/watch?v=P6susM9BT0A

Parte 2
http://www.youtube.com/watch?v=VqcNJ0UkGhg&feature=relmfu

Bayesian inference // Inferencia bayesiana

Links in English:

http://www.astro.cornell.edu/staff/loredo/bayes/


Links in Spanish:

http://www.ugr.es/~mcdiaz/bayes/


http://dxsp.sergas.es/ApliEdatos/Epidat/Ayuda/9-Ayuda%20An%E1lisis%20bayesiano.pdf


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Links en inglés:

http://www.astro.cornell.edu/staff/loredo/bayes/


Enlaces en español:


http://www.ugr.es/~mcdiaz/bayes/


http://dxsp.sergas.es/ApliEdatos/Epidat/Ayuda/9-Ayuda%20An%E1lisis%20bayesiano.pdf

A billion dollars for the winner!

How big is a billion? Beware, this is a tricky question. If you come from Europe you will probably answer “one million millions” (that is 1 followed by 12 zeros, or 10 to the 12^th power), but if you are American or Canadian, you will say “one thousand millions” (1 followed by 9 zeros, or 10 to the 9^th power).

This is the definition of billion from The Oxford Dictionary available online:

“In British English, a billion used to be equivalent to a million million (i.e. 1,000,000,000,000), while in American English it has always equated to a thousand million (i.e. 1,000,000,000). British English has now adopted the American figure, though, so that a billion equals a thousand million in both varieties of English.

The same sort of change has taken place with the meaning of trillion. In British English, a trillion used to mean a million million million (i.e. 1,000,000,000,000,000,000). Nowadays, it's generally held to be equivalent to a million million (1,000,000,000,000), as it is in American English.”

http://oxforddictionaries.com/words/how-many-is-a-billion

The word billion apparently entered English from French in the 17^th century, although its first recorded uses date from the 13^th century.

In Spanish, as I mentioned before, “billón” is a million millions:

http://buscon.rae.es/draeI/SrvltConsulta?TIPO_BUS=3&LEMA=billon

The same goes for French, German, and most of the languages in mainland Europe. 

Using the billion with 12 zeros is usually referred to as the “long scale”, the billion with 9 zeros being known as the “short scale”.  A very interesting and complete article about the subject may be found here:

http://en.wikipedia.org/wiki/Long_and_short_scales#cite_note-Smith-11

PLEASE ADD YOUR COUTRY AND THE NUMBER OF ZEROS THAT A "BILLION" HAS FOR YOU
Use the "comment" tool

Like this

SPAIN......12 zeros

SAMPLE SIZE CALCULATION // Cálculo de tamaño de la muestra

If you need a tool to calculate your sample size, you may want to try these links:

http://www.pwpamplona.com/wen/calcu/calculadora1.htm
An easy to use calculator from Navarra (Spain). In Spanish.

http://www.stat.ubc.ca/~rollin/stats/ssize/
A series of Java Script tools by Rollin Brant (University of British Columbia) to calculate sample size in the most frequent situations.

http://www.epibiostat.ucsf.edu/biostat/sampsize.html
A very complete web link from UCSF

http://biostat.mc.vanderbilt.edu/wiki/Main/PowerSampleSize
A free program from Vanderbilt University, by William Dupont and Walter Plummer.

http://hedwig.mgh.harvard.edu/sample_size/size.html
By David Schoenfeld , from the Massachusetts General Hospital- Harvard University.

http://www.sealedenvelope.com/power_binary.php
They also have a tool to create a randomisation list:
https://www.sealedenvelope.com/freerandomiser/v1/lists



More links in Spanish:
http://www.fisterra.com/mbe/investiga/9muestras/9muestras2.asp

http://www.psico.uniovi.es/Dpto_Psicologia/metodos/tutor.7/p3.html

http://www.seh-lelha.org/tamuestra.htm



Thanks for reading!

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Si quieres calcular el tamaño de tu muestra, quizá te interese probar los siguientes enlaces:


http://www.pwpamplona.com/wen/calcu/calculadora1.htm
Una calculadora fácil de usar de la Universidad de Navarra (España)

http://www.stat.ubc.ca/~rollin/stats/ssize/
Una serie de herramientas Java por Rollin Brant (Universidad de British Columbia), para calcular el tamaño de la muestra en las situaciones más frecuentes

http://www.epibiostat.ucsf.edu/biostat/sampsize.html
Un enlace muy completo de la Universidad de California San Francisco

http://biostat.mc.vanderbilt.edu/wiki/Main/PowerSampleSize
Un programa gratuito de la Vanderbilt University, por William Dupont y Walter Plummer.

http://hedwig.mgh.harvard.edu/sample_size/size.html
Por David Schoenfeld , del Massachusetts General Hospital- Harvard University.

http://www.sealedenvelope.com/power_binary.php
También tienen una herramienta para aleatorización en este enlace:
https://www.sealedenvelope.com/freerandomiser/v1/lists


Más enlaces en español:
http://www.fisterra.com/mbe/investiga/9muestras/9muestras2.asp

http://www.psico.uniovi.es/Dpto_Psicologia/metodos/tutor.7/p3.html

http://www.seh-lelha.org/tamuestra.htm


Gracias por leer!

How many tails do you have, if you’ll forgive the expression?

Q: I have been told that my distribution is “single tailed”. What does it mean? Is this something I should feel guilty about?

A: Not at all. In fact it has nothing to do with your anatomy. Here is the explanation of its meaning:
Generally speaking, when you are testing a hypothesis you want to know if there is any difference between two treatments.
If there is no difference, we call it “null hypothesis”, (“nullus” meaning “not any” in Latin), and statisticians always make this a priori assumption. If, after the statistical test, they find no difference between treatments, they assume the NULL HYPOTHESIS. If, on the contrary they find a difference, they REJECT the null hypothesis, and therefore accept the ALTERNATIVE HYPOTHESIS. That is how it works. 

Now, pay attention: If you are comparing A against PLACEBO, there is only ONE possible alternative hypothesis (The null hypothesis is A is equal to placebo, i.e. there is no difference between them):
A is better than placebo
(…but you would not even consider the possibility that placebo is better than A, because that would mean that A, instead of a treatment, is a risk factor).


But if you are comparing drug A against drug B, then we have TWO possible alternative hypotheses:
A is better than B
B is better than B

In the first case (A against placebo) we call it a SINGLE-TAILED distribution. In the second (A against B) we call it DOUBLE-TAILED a distribution.

And, to answer a message from a male reader of the blog (in case some others share the same doubt): no, double tailed distributions will not enhance your sexual life. You have a terrible misconception. 

Thanks for reading

CTSPEDIA

This is a link kindly suggested by Prof. Frank Harrel (University of Vanderbilt, USA).
CTSPEDIA is a collection of tools, educational materials and others. It deals with clinical, statistical and translational knowledge, and it is a good homepage for your internet browser too (I mean it), because it has so many useful things just a click away. CTSPEDIA is funded by an award from the NIH. Hope you enjoy it.

http://www.ctspedia.org/do/view/CTSpedia

How to learn literature searching strategies

If you feel you need an introduction to the secrets of Pubmed this is a link you will like:

http://guides.library.ucsf.edu/introtopubmed

It is a tutorial by the UCSF library. If you want to go deeper, they also have a wide array of tools to learn literature searching strategies:

http://www.library.ucsf.edu/help/tutorials

Free-to-use animations for academic teaching

http://www.wellcome.ac.uk/Education-resources/Teaching-and-education/Animations/index.htm

This is a resource from the Wellcome trust. Animations are available for DNA, Parasitic Diseases (protozoans and worms), Bacterial Diseases and Viral Diseases.

A tutorial for SPSS // Tutorial para SPSS

This link:

http://calcnet.mth.cmich.edu/org/spss/toc.htm

is a tutorial for SPSS from the Central Michigan University


This is another one from Harvard:
http://hmdc.harvard.edu/projects/SPSS_Tutorial/spsstut.shtml



Links in Spanish:

A PDF guide to SPSS 19, from Universidad de León (Spain)
http://www.unileon.es/ficheros/servicios/informatica/spss/spanish/IBM-SPSS_guia_breve.pdf

A very quick guide to SPSS 17 (just two pages long) from Universidad de Granada (Spain)
http://webcim.ugr.es/descargas/Manual_spss/breve_manual_SPSS.pdf


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Este link

http://calcnet.mth.cmich.edu/org/spss/toc.htm

es un tutorial para SPSS de la Central Michigan University


Este otro es de la Universidad de Harvard:
http://hmdc.harvard.edu/projects/SPSS_Tutorial/spsstut.shtml


Enlaces en Español:

Una guía en PDF para SPSS 19, de la Universidad de León (España)
http://www.unileon.es/ficheros/servicios/informatica/spss/spanish/IBM-SPSS_guia_breve.pdf

Una guía muy rápida (sólo dos páginas) para SPSS 17 de la Universidad de Granada (España)
http://webcim.ugr.es/descargas/Manual_spss/breve_manual_SPSS.pdf

COMMITTEE ON PUBLICATION ETHICS

http://publicationethics.org/

Information on most aspects of publication ethics. It includes guidelines, flowchart, e-learning and code of conduct.

Using PRISMA for systematic review reporting

http://www.youtube.com/watch?v=TVFYenon1Jo

A Youtube link to a tutorial of about one hour about the use of the EQUATOR network tool called PRISMA for reporting systematic reviews. By Prof. Moher from the University of Ottawa.

NOBODY IS PERFECT

Nobody is perfect

Or, in other words, we all make errors. Let’s see the types we can make:

Suppose you are testing the effectiveness of drug A compared to drug B. There are two real possibilities: either there is a difference between them or not.
After you perform the test, there are two possibilities: either you FIND a difference, or not.
You could put that in a 2x2 table:

                                   Real difference    No real difference
Computer says YES      Well done!         Type I error
Computer says NO      Type II error      Well done!

There are two ways you can go wrong. If you affirm there is a difference between A and B, and there is not, you have a type I or alpha error. If you are not able to find a real difference between A and B, you have a type II or beta error.

You can put it in other words:
If you reject a null hypothesis but you should have accepted it, you fall into a type I or alpha error. If you accept a null hypothesis but you should have rejected it, that’s a type II or beta error.

There is a mnemotechnic for it; Beta stands for Blind. (Beta error means you are blind to see a real difference between the two drugs).


Thanks for reading!

Free software form CDC. And more...

The Center for Disease Control and Prevention (CDC) offers a well known free statistical program, called Epiinfo. You can access it here:

http://wwwn.cdc.gov/epiinfo/

More resources:

Openepi is a free software program developed by the Rollins School of Public Health from Emory University in Atlanta, GA.

http://www.openepi.com/OE2.3/Menu/OpenEpiMenu.htm

Epidata. Free software by JM Lauritsen et al., from Denmark.

http://www.epidata.dk/

Netepi
http://sourceforge.net/projects/netepi/





Software for Systematic reviews and meta-analysis:

Revman is the software from the Cochrane Collaboration to feed in data and produce a systematic review:
http://ims.cochrane.org/revman


Epimeta, from the CDC
http://ftp.cdc.gov/pub/Software/epimeta/


MIX
http://www.mix-for-meta-analysis.info/

Software for Clinical Trials:

https://community.openclinica.com/

Healthknowledge and more...

Try these: 

http://www.healthknowledge.org.uk/e-learning/statistical-methods
A fully furnished, higly reliable and useful website. Free online course on statistical methods for Health Care workers. Tutorial on Evidence Based Medicine.

http://www.cebm.net/
Centre for Evidence Based Medicine of the University of Oxford.

http://www.gradeworkinggroup.org/
GRADE wepage. GRADE is a system to rank evidence and recommendations for a given heath problem. It is used by most major medical journal and evidence based medicine organisation.

http://www.epibiostat.ucsf.edu/biostat/sampsize.html
The website of the Division of Biostatistics of the University of California, San Francisco

http://www.ucm.es/info/matbio/piembb/enlaces/Free%20Statistical%20Software.htm
A site from the Universidad Complutende de Madrid, with software links.


http://www.stat.ufl.edu/vlib/statistics.html
This is a vast list of links to many statistical resources, from academic and government departments to software or stat journals. Published by the University of Florida.

What is an epidemiologist?

A clear definition of what an epidemiologist is from a lecture at Columbia University! 2 minutes long.

http://www.youtube.com/watch?v=jCK2mflwESM




By the way, the link to Mailman School of Public Health at Columbia University:

http://www.mailman.columbia.edu/academic-departments/epidemiology

Books: free links

Free links to Epidemiology and Statistics books:

http://publichealth.massey.ac.nz/publications/introepi.pdf

Neil Pearce´s “A Short introduction to Epidemiology”

http://faculty.vassar.edu/lowry/webtext.html

By Richard Lowry, from Vassar College

http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=12156

“Street-fight Mathematics”,

by Sanjoy Mahajan, from MIT

http://www.math.ku.dk/~sjo/papers/HaldBook.pdf

“A History of Parametric Statistical Inference from Bernouilli to Fisher, 1713 – 1935”. By Anders Hald

Graphics and data display

Here goes a link to the latest version of a pdf book on statistical data display, from Rafe Donahue (Vanderbilt University Medical Center).
with tips and advise for those who want to show their study results in a clear elegant manner.
http://biostat.mc.vanderbilt.edu/twiki/pub/Main/RafeDonahue/fscipdpfcbg_currentversion.pdf


Also check this link to Tufte's book:
http://www.amazon.com/Visual-Display-Quantitative-Information/dp/0961392142

International statements

These are international statements for the reporting of different types of studies.

Diagnostic studies:
http://www.stard-statement.org/

Systematic reviews:
http://www.prisma-statement.org/

Observational studies:
http://www.strobe-statement.org/

Clinical trials:
http://www.consort-statement.org/

We need more biostatistical training. And are aware of it

This paper from the Mayo Clínic Proceedings shows that mosto doctors feel they should improve their biostatistical training. They also find that Statistics is an important and useful tool for their careers.

http://www.mayoclinicproceedings.com/content/82/8/939.full

P for novices // P para novatos

p...
What is p value (also called significance)? How does it work? Curiously enough, many collegues at the hospital clearly know how to interpret a p value (i.e, they can tell you if a study is significant or not), but have trouble trying to explain the exact meaning of, say, a p = 0. 01.
In practice most of us would answer: if p is lower than 0.05, the result of the study is significant. If higher, non significant. Simple. But what does it mean?
So let´s go for it. Imagine we are comparing two treatments A and B. And imagine there is no real difference between A and B, in terms of their efficacy. We call p the probability that,  when you perform a statistical test (whichever you need, we will try to roughly cover that in a future post), you FIND a difference by chance.
In other words, when you perform your test you have a chance that it does not show reality, but on the contrary get a false result. And, as there is no difference between A and B, that false result means that you SEE a difference.
And p value has nothing to do with the difference of the effect found (A being 10%, 30% or 70% more effective than B). You may find a tiny difference between the effectiveness of the two drugs, with a very significant p value. Or a huge difference with a clearly non significant p.
In fact p is like a friend. You can trust or not your friend (that is the p value) on what he tells you (that is the difference between A and B that you find; 2%, 25%, or whatever).
Why 0.05? Well that is a value everyone has agreed upon. It does not come from a formula or anything. When we try our test, if p= 0.05, it means that we want to be wrong once every 20 times at most.


Was this post useful to you? Would you like to talk about any specific subject? Please share your comments!

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p...
¿Qué es la p (también llamada significación estadística)? ¿Cómo funciona? Cusiosamente, muchos colegas del hospital saben interpretar un valor de p (por ejemplo, pueden decir si un estudio es significativo o no) pero tienen problemas para definir el significado exacto de una p de 0,01 (por ejemplo).
En la práctica, diríamos que una p menor de 0,05 es significativa, y mayor, no significativa, pero ¿que quiere decir esto?
Vamos allá. Imaginemos que tenemos dos tratamientos A y B, y que no hay diferencias en cuanto a su eficacia (son igualmente eficaces). Llamamos p a la probabilidad de encontrar una diferencia entre A y B simplemente por azar (recordemos que no hay diferencias entre A y B).
El valor de la p no tiene nada que ver con la diferencia entre tratamientos (entre A y B puede haber una diferencia de eficacia del 10 , del 30 o del 70%). Por ejemplo, se puede encontrar una diferencia muy pequeña entre A y B con una p enrormemente significativa, o una gran diferencia con una p claramente no significativa.
En realidad p es como un amigo. Lo que nos dice nuestro amigo es la diferencia entre A y B. La probabilidad de que se equivoque es la p.
¿Por qué 0,05? Por puro acuerdo. No viene de de ninguna fórmula. Cuando p= 0,05 significa que en nuestro test estadístico nos vamos a equivocar 1 de cada 20 veces.

Free (and not so free) online resources

This is a review of online biostatistics links and resources. Some of them are free; some others are not, although they are worth the money.

http://ocw.jhsph.edu/courses/introbiostats/

An Opencourseware free course offered by the Johns Hopkins School of Public Health. They also offer two courses on Methods in Biostatistics:

http://ocw.jhsph.edu/courses/MethodsInBiostatisticsI/

and fundamentals of epidemiology:

http://ocw.jhsph.edu/courses/FundEpi/

http://ocw.mit.edu/courses/mathematics/18-05-introduction-to-probability-and-statistics-spring-2005/

The OpenCourseWare (OCW) is an initiative started by the prestigious Massachusetts Institute of Technology. It is a free collection of courses previously lectured at the MIT. A great idea followed by other universities. MIT OCW offers a broad array of courses on many disciplines, and they have this course titled “Introduction to probability and Statistics”. Free of charge.

http://ocw.tufts.edu/Course/1/Coursehome

Another OCW resource, this time from Tufts University. Highly recommendable.

http://isites.harvard.edu/icb/icb.do?keyword=k83983

An online course from Harvard, titled Elements of Clinical Investigation. Charge ranges from $1,025 (non-credit) to $1950 (if you are aiming for graduate credit).

http://isites.harvard.edu/icb/icb.do?keyword=k84313

An introductory course on Statistics from Harvard. Same price as above.

http://extension.berkeley.edu/catalog/course26.html

A 785$ course offered by the University of California Berkeley. You can enroll anytime, and have 6 months to finish it.

http://bibalex.org/supercourse/courses/biostatistics1.htm

A bilingual course (in English and Spanish) by Dr. Nicolas Padilla Raygoza, a Mexican pediatrician and epidemiologist. Free.

http://oli.web.cmu.edu/openlearning/forstudents/freecourses/statistics

Two free online courses from the Carnegie Mellon University. One is on Probability and Statistics and the other on Statistical Reasoning. You need to log in to take them, but at no charge.

New Year Address

This new blog seeks to share information about medical statistics, evidence based medicine and research methodology. Everyone is welcome to share and comment. All constructive criticism is encouraged!

On one hand anyone can upload (and find) resources, tools, publications of a certain "academic" flavour.
On the other hand this intends to be a forum to publicly comment any health subject where a methodology issue should be improved.

And as the first post of the year, I would like to share the outstanding blog by Ben Goldacre, BAD SCIENCE:

http://www.badscience.net/




Cheers