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Professor Andy Field's Blog (14)

Bonferroni correcting lots of correlations

Someone posed me this question:

Some of my research, if not all of it (:-S) will use multiple correlations. I'm now only considering those correlations that are less than .001. However, having looked at bonferroni corrections today - testing 49 correlations require an alpha level of something lower than 0.001. So essentially meaning that correlations have to be significant at .000. Am I correct on this? The calculator that I am using from the…


Added by Professor Andy Field on April 25, 2012 at 9:31 — 4 Comments

SPSS is not dead

This blog was published recently showing that the use of R continues to grow in academia. One of the graphs (Figure 1) showed citations (using google scholar) of different statistical packages in academic papers (to which I have added annotations).…


Added by Professor Andy Field on April 14, 2012 at 9:47 — 5 Comments

One-Tailed Tests

I’ve been thinking about writing a blog on one-tailed tests for a while. The reason is that one of the changes I’m making in my re-write of DSUS4 is to alter the way I talk about one-tailed tests. You might wonder why I would want to alter something like that – surely if it was good enough for the third edition then it’s good enough for the fourth? Textbook writing is quite an interesting process because when I wrote the first edition, I was very much younger, and to some extent the content…


Added by Professor Andy Field on April 2, 2012 at 10:36 — 5 Comments

Rock makes you Racist ... Apparently

Like buses, you don’t get a blog for weeks and then two come at once. I saw today this headline: Does listening to rock make you racist? Seven minutes of Bruce Springsteen makes students favour white people over others in the daily mail online. They also included a helpful picture of Scott Weiland wearing a…


Added by Professor Andy Field on March 19, 2012 at 18:24 — 1 Comment

TwitterPanic, NHST, Wizards, and the cult of significance again

****Warning, some bad language used: don't read if you're offended by that sort of thing****

I haven’t done a blog in a while, so I figured I ought to. Having joined Twitter a while back, I now find myself suffering from TwitterPanic™, which is an anxiety disorder (I fully anticipate to be part of DSM-V) characterised by a profound fear that people will unfollow you unless you keep posting things to remind them of why it’s great to follow you. In the past few weeks I have posted a…


Added by Professor Andy Field on March 18, 2012 at 13:30 — 1 Comment

Factor Analysis for Likert/Ordinal/Non-normal Data

My friend Jeremy Miles sent me this article by Basto and Periera (2012) this morning with the subject line ‘this is kind of cool’. Last time I saw Jeremy, my wife and I gatecrashed his house in LA for 10 days to discuss writing the R book that’s about to come out. During that stay we talked about lots of things, none of which had anything to do with statistics, or R for that matter. It’s strange then…


Added by Professor Andy Field on January 31, 2012 at 21:42 — 3 Comments

Newspapers and 7 Core Statistical Concepts

There have been a few news stories recently about misunderstanding of statistics; especially confusing correlation with cause. For example, the Guardian ran this story/tutorial ( Hot on the heels of that useful reminder, came a story linking unemployment in the UK to immigration from outside of the EU ( By the time the Daily Mail had got their hands on the story the ‘link’ had…


Added by Professor Andy Field on January 12, 2012 at 11:17 — 2 Comments

Bias in End of Year Polls (and Happy New Year)

So, in rolls 2012 and out rolls another year. I like new year: it’s a time to fill yourself with optimism about the exciting things that you will do. Will this be the year that I write something more interesting than a statistics book, for example? It’s also a time of year to reflect upon all of the things that you thought you’d do last year but didn’t. That’s a bit depressing, but luckily 2011 was yesterday and today is a new year and a new set of hopes that have yet to fail to come to…


Added by Professor Andy Field on January 3, 2012 at 10:30 — No Comments

Discovering Statistics Using SPSS 4

This will be brief because, you know, it's nearly Christmas and for those of us that use this as an excuse to eat too many sweets and drink too much beer and wine, it's not a time for statistics. However, after Christmas will very much be a time for statistics in the Field household (my wife can't wait ....) because the other day I opened the bar of chocolate with the golden ticket to statistics hell and back contained within. Yes, that's right, it's time to write the fourth edition of the…


Added by Professor Andy Field on December 19, 2011 at 11:30 — No Comments

Should I buy This Book?

I’m thinking of buying this book:


On the face of it it seems like the kind of book I’ll enjoy. Admittedly I’d enjoy a nice biography about Metallica or some other heavy rock band more, but I need to maintain the façade of loving statistics. It seems to be an historical account of why we use significance testing and why…


Added by Professor Andy Field on November 2, 2011 at 10:15 — 6 Comments

The Joy of Confidence Intervals

In my last blog I mentioned that Null Hypothesis Significance Testing (NHST) was a bad idea (despite most of us having been taught it, use it and possibly teach it to future generations). I also said that confidence intervals are poorly understood. Coincidentally, a colleague of mine, knowing that I was of the ‘burn NHST at the stake’ brigade recommended…


Added by Professor Andy Field on October 17, 2011 at 13:30 — 7 Comments

Top 5 Statistical Fax Pas

In a recent article (Nieuwenhuis, et al., 2011, Nature Neuroscience, 14, 1105-1107), neuroscientists were shown to be statistically retarded … or something like that. Ben Goldacre wrote an article about this in the Guardian newspaper, which caused a bit of a kerfuffle amongst British psychologists because in the first published version he accidentally lumped psychologists in…


Added by Professor Andy Field on October 10, 2011 at 12:00 — 3 Comments

Meta-Analysis and SEM

Someone recently asked me about how to incorporate results from Structural Equation Models into a meta-analysis. The short answer is 'with great difficulty', although that's not terribly helpful.
One approach it to do the meta-analysis at the correlation level, which is good if the SEM studies report the zero-order correlations (which hopefully they do). That is, you use meta-analysis to estimate pooled values of correlations between variables. Imagine you had three variables:…

Added by Professor Andy Field on October 3, 2011 at 10:46 — No Comments

Reshaping data in R

One of the frustrating things about using R (although it can be a positive thing too) is that there are often 25 different ways to do the same, or almost the same thing. Therefore, you want to do something, you have a look around, and then you find something that looks like it does what you want, but it doesn’t. It almost does, but it doesn’t. A few dead ends later and you have hit on something that works. The relief is tangible.


As I use R more (I’m supposed to be writing a…


Added by Professor Andy Field on March 29, 2011 at 18:30 — No Comments

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