Wisdom of the Cloud

Many summers ago when I started out in the Craft, I could log onto the trusty DEC-20 literally anywhere in the world, and use SPSS or BMDP to analyse data. Nowadays, I have to have IBM SPSS or Stata installed on the right laptop or computer, and bring it with me, wherever I may roam, and wonder dreamily  if I could just access my licensed stats packages from anywhere, like a library, a beach, a forest, a coffee shop.

One option would to subscribe to a stats package in the Cloud! Iin terms of main line stats packages, https://www.apponfly.com/en/ has R (free plus 8 euro’s ($A12.08) per month for platform, NCSS 10 at 18/27.19 per month + platform, IBM SPSS 23 Base 99/149.54 ditto and Standard (adds logistic regression, hierarchical linear modelling, survival analysis etc) for 199/300.59 per month + platform.

Another option, particularly if you’re more into six sigma / quality control type analyses, is Engineroom from http://www.moresteam.com at $US275 ($A378.55) per year.

Obviously,  compare the prices against actually buying the software , but to be able to log in from anywhere, on different computers, and analyse data,  sigh, it’s almost like the summer of ’85!

Snappy Stepwise Regression

Stepwise regression, the technique that attempts to select a smaller subset of variables from a larger set by at each step choosing the ‘best’ or dropping the ‘worst’ was developed back in the late 1950’s by applied statisticians in the petroleum and automotive industries. With an ancestry like this, there’s no wonder that it is often regarded as the statistical version of the early 60’s Chev Corvair, at best only ‘driveable’ by expert careful users, or in Ralph Nader’s immortal words and title of his 1966 book  ‘Unsafe at Any Speed’.

Well maybe. But if used with cross-validation and good sense, it’s an old-tech standby to later model ‘lasso’ and ‘elastic net’ techniques. However, there’s an easy way for a bit of a softshoe shuffle of the old stepwise routine. See how well (preferably on a fresh set of data) forward entry with just one or, maybe two, or at most three variables do, compared with larger models. (SAS and SPSS allow the number of steps to be specified).

Of if you’d like to do some slightly fancier steps it in twotone spats, try a best subset regression (available in SAS, and SPSS through automatic linear, and Minitab and R etc), of all one variable combinations, two variables, three variables.

The inspiration for this is partly from Gerd Gigerenzer’s ‘take the best’ heuristic, taking the best cue or clue often beats more complex techniques including multiple regression etc. ‘Take the best’ is described in Prof Gigerenzer’s great new general book Risk Savvy: How to Make Good Decisions (Penguin, 2014) http://www.penguin.co.uk/nf/Book/BookDisplay/0,,9781846144745,00.html as well as his earlier academic books such as Simple Heuristics That Make Us Smart (Oxford University Press, 1999)

See if a good little model can do as well as a good (or bad) big ‘un!.


Further Future Reading

Draper NR, Smith H (1966) Applied regression analysis (and later editions). Wiley: New York.

John and Betty’s Journey into Statistics Packages*

In past days of our lives, those who wanted to learn a stats package, would attend courses, and bail up/bake cakes for statisticians, but would mainly raise the drawbridge, lock the computer lab door and settle down with the VT100 terminal or Apple II or IBM PC and a copy of the brown or update blue SPSS Manual, or whatever.

Nowadays, folks tend to look things up on the web, something of a mixed blessing, and so maybe software consultants will now say LIUOTFW (‘Look It Up On The Flipping Web’) rather than the late, great RYFM (‘Read Your Flipping Manual’).

And yes, there are some great websites, and great online documentation supplied by the software venders, but there are also some great books, available in electronic and print form. A list of three of the many wonderful texts available for each package (IBM SPSS, SAS, Stata, R and Minitab) can be downloaded from the Downloadables section on this site.

IBM SPSS (in particular), R (ever growing), and to a slightly lesser extent SAS, seem to have the best range of primers and introductory texts.
IMHO though, Stata could do with a new colourful, fun primer (not necessarily a Dummies Guide, although there’s Roberto Pedace’s Econometrics for Dummies (Wiley, New York, 2013) which features Stata), perhaps one by Andy Field, who has already done superb books on SPSS, R and SAS.

While up on the soapbox, I reckon Minitab could do with a new primer for Psychologists / Social Scientists, much like that early ripsnorter by Ray Watson, Pip Pattison and Sue Finch, Beginning Statistics for Psychology (Prentice Hall, Sydney, 1993).

Anyway, in memories of days gone by, brew a pot of coffee or tea, unplug email, turn off the phone and the mobile/cell, and settle in for an initial night’s journey, on a set or two of real and interesting data, with a good stats package book, or two!

*(The title of this post riffs off the improbably boring and stereotyped 1950’s early readers still used in Victorian primary (grade) schools in the 1960’s
http://nla.gov.au/nla.aus-vn4738114 (think Dick and Jane, or Alice and Jerry), as well as the far more entertaining and recent John and Betty’s Journey into Complex Numbers by Matt Bower http://www.slideshare.net/aus_autarch/john-and-betty )

Electric Stats: PSPP and SPSS

Most people use computer stats packages if they want to perform statistical or data analysis. One of the most popular packages, particularly in psychology and physiotherapy, is SPSS, now known as IBM SPSS. Although there is room for growth in some areas such as ‘robust regression’ (regression for handling data that may not follow the usual assumptions), IBM SPSS has many jazzy features / options such as decision trees and neural nets and Monte Carlo simulation, as well as all the old faves like ANOVA, t-tests and chi-square.

I love SPSS and have been using it since 1981, back when SPSS analyses had to be submitted to run after 11 pm (23:00) so as not to hog the ‘mainframe’ computer resources. Alas, as with Minitab, SAS and Stata and others, SPSS can be expensive if you’re not a student or academic. An open source alternative that is free as in sarsparilla and free as in speech, is GNU PSPP, which has nothing whatsoever to do with IBM or the former SPSS Inc.

PSPP has a syntax or command line / program interface for old school users such as myself, *and* a snazzy GUI or Graphic User Interface. Currently, it doesn’t have all the features that 1981 SPSS had (e.g. ‘two-way ANOVA’), let alone the more recent features, although it does have logistic regression for binary outcomes such as depressed / non depressed. PSPP is easy to use (easier than open source R and perhaps even R Commander, although nowhere near as powerful).

PSPP can handle most basic analyses, and is great for starters and those using a computer at a worksite etc where SPSS is not installed, but need to run basic analyses or test syntax. The PSPP team is to be congratulated!

http://www.gnu.org/software/pspp/   free, open-source PSPP

http://www-01.ibm.com/software/analytics/spss/  IBM SPSS

(students and academics can obtain less expensive versions of IBM SPSS from http://onthehub.com)