The Joy of Stats
Statistics – the very word is guaranteed to bring a shudder of terror to the average undergraduate, and even full-grown lecturers have been known to quake in fear before its awesome power. Most psychology undergraduates don’t come from a hard-science or mathematics background, and statistics are probably the number one thing that they struggle with during their psychology courses. Personally, I got through my undergraduate stats exams with a mixture of vague understanding and rote memorisation, and it was only during my PhD that I actually started learning how to do things properly and, more importantly, actually understanding what I was doing, and why.
This is not the place to give any detailed information on the basics of statistics. That kind of material has been covered many, many times before by people infinitely more qualified than I. For that kind of stuff, a good place to start would be Andy Field’s book, available here. Andy explains things very clearly and is actually a very nice chap as well. What I’d like to do instead is do a quick run-down of popular stats software, and point out some resources which can help if you run into trouble.
SPSS – Probably the most popular choice for psychology departments, and therefore the most likely piece of software you’ll encounter as a psychology undergraduate. Currently on version 19, which has a nice graphical interface for most functions and also a very useful script interface. Can do pretty much everything you’re ever likely to need as an undergraduate. Traditionally it’s been weak on graphing/visualisation capabilities (the default graphs look a bit, well… rubbish) but they seem to be addressing this in the newest versions. It’s also somewhat buggy, prone to unexpected crashes, and a bit of a resource-hog.
SAS – The choice of serious professional statisticians. Does everything that SPSS does and also includes tools for more specialist procedures, often used in psychometrics (structural equation modelling, factor analysis, principal components analysis). Interface is much more script-dependent than SPSS, so not as friendly for the beginner. Does produce beautiful graphics though.
Matlab – Again, a professional choice. Has a large number of basic statistics functions (mean, mode, median, standard deviation etc.) built into the base package, and these can be further enhanced by use of the statistics toolbox. Pretty much entirely based on a scripted interface, albeit a reasonably easily human-readable one. Can produce very attractive charts and plots using only a single line of code. Matlab is much more than just a statistics package however, and I’ll be going into a lot more detail about what it can do in a future post I have planned.
Excel – Microsoft’s spreadsheet application, available as part of the MS Office suite of applications. Noteworthy not for its capabilities but for its ubiquity and relative ease-of-use. Only contains the most basic (descriptive) statistical functions. ‘Proper’ statisticians are generally pretty rude about Excel (see this page) but I find it very useful for basic tasks like totting up means and basic graphing. You should be extremely cautious about using it for anything more complex though. This page contains some good resources about how to use it well.
Others – There are literally hundreds of other bits of software floating around the internet which are either general-purpose analysis solutions, or specialised for particular statistical procedures. Clearly, I haven’t used most of them so can’t really comment, but I’m pretty confident in saying that if you have a stats problem, someone, somewhere has probably written something which contains a solution. Lists (probably only partial ones) are available here and here.
Graphing/Plotting – As mentioned above, SPSS’s built-in plotting functions are pretty heinous, so I tend to use Excel for rough, back-of-an-envelope stuff and SigmaPlot for publication-quality stuff. The SigmaPlot interface is a bit difficult to understand at first, but you soon get the hang of it. Again, there are loads of other alternatives out there if you search for them.
Some web resources on Stats:
Statistics Hell – Andy Field’s Website – loads of great resources here if you poke around a bit. Also an inexplicably large number of pictures of his cats.
Stat Trek – Lots of very good tutorials.
Stat-help – Free, online help with statistics questions from qualified consultants.
Hyperstat – A free online statistics textbook, with links to lots of other resources too.