Rules of engagement

My Books (General Questions)

Statistics

SPSS

R

Responses

Can I contact you?  There are normally three reasons why people want to contact me (in order of frequency). I’ll deal with each in turn.

  1. Ask me a statistics question – you can contact me under under three conditions:
    • You try to help yourself first by checking these FAQs, blog, book errata (see menus), books, posting the question on ResearchGate (to which I contribute), checking other useful resources (especially for R) such as QuickR, and StackOverflow. I prefer to answer questions on these public forums, rather than email, so answers are available to everyone.
    • You don’t take offence if I don’t have time to answer. I respond to hundreds of questions each year so if you don’t get a response it’s just the logistics of my life and not because I’m a heartless arsehole who doesn’t care about your statistical plight. It’s really not nice to call me a ‘pig cunt’ just because I decided to use the little spare time I have sleeping, being with my family, having some fun rather than answering an unsolicited question from a complete stranger.
    • If I do respond, and it’s helpful, you consider showing your appreciation by donating to the NSPCC (a UK charity that acts to protect children and prevent child cruelty) via my NSPCC fundraising page.
  2. Feedback about one of my books – yes, please get in touch.
  3. You’re interested in my research – yes, please get in touch.
  4. You think that my office is constructed from piles of my own books that I distribute to random people for free – I will enjoy the obligatory brief paragraph of sucking up, for sure, but I won’t be sending you a free book because, you know, I give my limited author copies to people I actually know.

Will I analyze your data or enter into consultancy about data analysis? The short answer is no. I’m fairly busy with my own research, answering emails, generally trying to help everyone in the universe. I probably could charge people lots of money for analysing their data for them, but I’m happier just answering what questions I have time for for free or in return for charity donations. I don’t have time to answer long questions, but I do answer some short ones when I have time. Don’t be offended though if you don’t get a reply. Twitter is good for very short questions  or my official facebook page. If you want a detailed discussion about statistics then try Adam Hafdahl or any other proper consultant.

Will I help with assignments or masters/PhD work? It is completely inappropriate to ask me to help with assignments for which you get marked. First, it’s deceitful to take credit for work when you have been advised by a third party without the markers knowledge. Secondly, I don’t want to be sued if my advice is perceived to contribute to a poor mark. For masters and PhD work your first port of call should be your supervisor: it’s their job to help you, not mine. If they feel out of their depth then they are welcome to contact me. However, I will not get embroiled in ‘My supervisor says x, but what do you think?’ type of discussions because your supervisor knows the nuances of your research area whereas I do not, and I do not want to give bad advice.

Where can I find the companion website/data/book resources? The companion websites for my main textbooks are linked in the footer of this webpage. These sites are run by my publisher and contain all of the resources associated with each book (with some handouts mirrored here too).

Where can I find the companion website/data/resources for the previous editions of [insert name of my book]? The way new editions work is that generally I keep the examples and datafiles from previous editions but add some new ones. Therefore, if you download the datafiles for the fourth edition, they will contain pretty much everything you need for the third edition etc. So, please try not to panic if you can’t locate the datafiles for earlier editions of the book, just download the datafiles from the website for the latest edition and they should contain everything you need. This applies to task answers and other resources, the latest versions will contain the same tasks and answers as previous editions (although they might be in slightly different orders across editions).

Will I write a book on X? Having spent 8 years developing my latest book An Adventure in Statistics, and I’m due updates for the SPSS and R books it’s fair to say that I’m unlikely to be writing any other new books for a while.

Is there an [insert name of language] version of your book/can I translate your book into [insert name of language]? The second edition of the SPSS book was translated into Portuguese, but that book is quite out of date now. As far as I know all other books in all versions are available only in English. The way translations work is that they have to be negotiated with my Publisher, SAGE (I don’t have any direct influence over these things because they own the publication rights). Usually what happens is that a publisher in another country decides they want to publish a translation, and then they arrange that with SAGE. If you personally wanted to do a translation then I think the best thing is either to find a publisher in your country and propose the idea to them, and they in turn discuss with SAGE, or you could contact SAGE directly and see what they suggest. I think the correct person to contact is Katherine Ryan in the rights team.

When am I updating x [insert name of one of my books]? My current schedule is:

  • Discovering Statistics Using IBM SPSS Statistics. I’m writing Edition 5 this year with a view to publish in November 2017 (fingers crossed).
  • Discovering Statistics Using R: I’m really keen to do this but have to get the SPSS book done first. Realistically I think that means it won’t see the light of day until 2019 if I’m not a withered husk by then.
  • Discovering Statistics Using SAS: no update planned at present, and I think there is unlikely to be one ever.
  • How to design and Report Experiments: Also keen to do this but I’m not sure when it will happen unless someone can invent more hours in the day.

Is there an ebook version of x [insert name of one of my books]?  Yes! Here’s a list that may, or may not, be definitive:

An adventure in statistics: Amazon Kindle, Perusall (whatever the hell that is!)
Discovering statistics using IBM SPSS Statistics: Amazon Kindle, VitalSource, Google Play, eBooks.com, Kobo, Perusall
Discovering statistics using R: Amazon Kindle, VitalSource, Google Play, eBooks.com, Kobo.
Discovering statistics using SAS: Amazon Kindle, VitalSource, Google Play, eBooks.com, Kobo.
How to Design and Report Experiments: Amazon Kindle, VitalSource, Google Play, eBooks.com, Kobo.

Is there a nonparametric equivalent of x? Apart from the obvious nonparametric tests there are now a huge family of tests known as robust tests. These tests typically rely on bootstrapping, trimmed means or both to produce results that are not dependent on the shape of your data/population/sampling distribution. SPSS has a bootstrapping module, but it’s pretty limited. If you want to do Robust methods, the best reference source is Rand Wilcox’s book. As part of this book he provides files to run robust ANOVA, ANOVA, MANOVA and multiple regression as well as a whole host of other procedures. If there is a robust method, it is in Rand’s book, and he has written a macro procedure to run it! You can also download these macros from his website. His Macros work in the freeware package R. We have practical examples of how to use Wilcox’s tests in R in our book Discovering Statistics Using R.

What is the ‘corrected model’ in SPSS ANOVA output? The corrected model represents the overall effect of all main effects and interactions in the model.In other words it is the amount of variability in the outcome that can be explained simultaneously by all main effects and interactions. This is not the same as the corrected total, which also includes the error in the model. Usually, this effect is not particularly interesting for interpreting the results because hypotheses are typically tested by any interaction terms, or in the absence of interaction terms the main effects.

Why does my sphericity test look weird? Sphericity applies only when you have three or more repeated measures conditions (with only two conditions sphericity must hold true … if you read the explanation of what sphercitiy is in one of my books you’ll see why, because it relates to the variances of DIFFERENCES between conditions being equal, and with only 2 conditions there is only one set of differences). Anyway, if you have only two conditions SPSS will produce lots of blanks in the table for Mauchley’s test (but note the epsilon values are 1, which tells you that the data have perfect sphericity), these blanks might seem confusing, but they’re just there because it can’t test for sphericity with only two conditions. It probably just shouldn’t produce a table at all, but if it did that you’d wonder where the table had gone.

I can’t find something in the SPSS menus? If you can’t find something it probably means your license doesn’t include the module you need. SPSS has four versions: base, standard, professional and premium. You can see a comparison of versions here.

My R Code doesn’t work. There are some typos that might affect things, and packages change dynamically so the code will become out of data. There is a list of errata here, so check their first. Also try googling the error and if you find a solution I’d be grateful if you’d tell me so I can update my list.

The DSUR package doesn’t exist/work. Jeremy Miles (my co-author) is working on the package. He was supposed to finish it quite a while ago but hasn’t (and probably never will). It’s reasonable to assume at this point that a package won’t be developed until I write the second edition of the book. You can access all of the functions by downloading the script file for the chapter, locating the function you want, highlighting it and executing it. The function will then be available to you for the rest of your R session.