What is a Sampling Distribution?

The sampling distribution is one of the most important concepts in inferential statistics, and often times the most glossed over concept in elementary statistics for social science courses. This article will introduce the basic ideas of a sampling distribution of the sample mean, as well as a few common ways we use the sampling distribution in statistics. When we conduct a study in psychology, this almost always includes taking a sample and measuring some aspect…

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An Illustrative Guide to Statistical Power, Alpha, Beta, and Critical Values

From my interactions with undergraduate students, it seems that even though these definitions are easy to recite, they are difficult to be integrated into a comprehensive whole. I hope here to show how to conceptually integrate them into a cohesive picture. Everything begins with reality: the “Reality Continuum” I call this green line “Reality Continuum” (rather grand, no?) because you will take your ideas, and do a reality check against it via data analysis (within the traditional statistical framework–it is definitely NOT…

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Mediating and Moderating Variables Explained

What is the difference between a mediator and a moderator? One of my former academic advisors used to always say “be a walking laboratory”. I think it’s a very poetic way of describing a core feature of psychological research—to come up with theories or explanations for various phenomena we observe. Sometimes there isn’t a clear-cut relation between a dependent and independent variable. In those cases, a mediating variable or a moderating variable can provide a…

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The Significance of Impression Formation: Reinterpreting Early Social Psychology Findings Using Modern Stats

Solomon Asch may be best known in social psychology for his 1951 Conformity Studies in which he brought participants into a room with seven confederates—actors pretending to be other participants—and had them recount the length of a line.  Before demonstrating that normative pressure can lead people to lie, Asch was one of the foremost researchers on impression formation.  He was interested in how we judge others and their personality based off small bits of information. 

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Python for the Social Sciences: Toolkit Essentials

  Why Py? Why should psychologists, or social scientists more generally, care about programming? The fact is anyone who uses softwares for data analysis relies on programming and many wonderful tools exist to give researchers improved control over their data for more efficient workflow. Although learning programming may seem an insurmountable task, with the right tools a few simple lines of code can accomplish wonderful things. I hope this blog will present, in a very…

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Odds Are: On the difference between odds, probability, and risk ratio.

Odds, Probability, Chance, Risks: Interchangeable? Not so much. What does it mean to say “smokers are X times more likely to get lung cancer than non-smokers?” What about when the weather channel says, “there is a 10% chance of rain?” The odds of 1 to 10 of winning? These words are often used in casual conversations as somewhat interchangeable, and can be rather confusing. I remember being very excited to learn about them for the first…

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Interview Tips for Students Applying to PhD Programs in Psychology

Preparing for interviews for a PhD program in psychology can be very stressful as well as very exciting. This is likely the first time that you will be interacting face to face with multiple professors and graduate students from the program you are applying for, and it is important to make a good impression. It can be difficult to find the ideal balance between self-praise and humility; you want to sell yourself as a dedicated…

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How will Big Data shape psychology research?

I’m sure all of you have heard of the Big Data movement going on right now. From the Harvard Business Review to David Brooks in the NY Times, everyone seems to be talking about the power of big data to provide “insights” into the inner workings of the world. Of course as a scientist, recognizing the power of data is not news to me. But I was interested in an article in the Psychological Science Observer that talks about how…

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Biased results — field of psych takes the heat

The pressure to publish positive findings (instead of null results) is present across scientific discipline, but several researchers have argued that the field of Psychology is the most biased offender.  An article posted last week in Nature.com discussed these biases – and presents two potential solutions one of which was suggested by UCLA researcher Dr. Matt Lieberman.  Click here to read the full article and suggested solutions.

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Revisit: fMRI and the “lit up” brain

I wrote a post a few months ago about some common misconceptions about functional magnetic resonance imaging (fMRI), and one of my main points was that the term  ‘lights up”, which is often used when describing the areas of the brain that respond to a task, is misleading. Here is what I said on the subject: First, fMRI does not detect electrical changes in the brain, as ‘lights up’ would imply.  Neurons in the brain communicate…

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Quick Tips for Becoming Poll-Literate

If you’re a political junkie like me, or just a casual election-follower, you’ve probably read a few polls that made your jaw drop.  Here are some things a skeptical poll consumer should look for before letting their jaw fully drop.   Selection Bias One of the first questions you should ask yourself when you read a poll is “What kinds of people did they ask?”  What we want in a poll is to get an…

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“…the difference between significant and not significant is not itself necessarily significant.”

The quote above comes from a perspective published in Nature Neuroscience this past summer by Nieuwenhuis and colleagues. They detail a surprisingly common mistake in the statistical analyses carried out by some studies published in prominent journals. It might be easier to first illustrate the mistake with an example. Let’s say I give a control group and a treatment group a task. To measure performance, I record how quickly each subject completes it. The control…

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I WANT MY FAME TV: VALUES ON TV FOR CHILDREN 1967-2007

It’s an age-old refrain — adults claim that kids today are completely different from when they were growing up, usually for the worse. And that claim often extends to the TV shows that kids are exposed to – more sex, less depth, endless shows about celebrities and reality TV show stars. But hasn’t Hollywood always glamorized being rich and famous? The pursuit of fame is embedded in the fabric of our society, in America –…

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How not to conduct research: Online ethics edition

Note: Everything in the following article and the provided links (at least at the time of posting) is work-safe, though some links may contain explicit language.  However,  please exercise caution in clicking other links found on the web pages referenced here! A quick Google search for recent Boston University grads Ogi Ogas and Sai Gaddam reveals buzz about their book, “A Billion Wicked Thoughts,” out today.  Ogas and Gaddam analyzed traffic to erotic web sites…

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