Monday, February 19, 2007

Survey design tips -- detailed yet readable

There's a fairly detailed, yet quite readable tutorial giving survey design tips here. A sample:

If you want only one answer from each person, ensure that the options are mutually exclusive. For example:

In which of the following do you live?
A house
An apartment
The suburbs

This question ignores the possibility of someone living in a house or an apartment in the suburbs.


And there's this:

Make sure you include all the relevant alternatives as answer choices. Leaving out a choice can give misleading results. For example, a number of recent polls that ask Americans if they support the death penalty "Yes" or "No" have found 70-75% of the respondents choosing �Yes.� Polls that offer the choice between the death penalty and life in prison without the possibility of parole show support for the death penalty at about 50-60%. Polls that offer the alternatives of the death penalty or life in prison without the possibility of parole, with the inmates working in prison to pay restitution to their victims’ families have found support for the death penalty closer to 30%.


(Via All This ChittahChattah)

Sunday, February 18, 2007

Convert string variables to numeric using SPSS syntax

I like to do everything in SPSS syntax so my entire analysis is replicable from data entry to statistical operations. After strapping on my hip waders and stepping ever so gingerly into the muck that is the SPSS "help" files, I finally figured out how to convert string variables to numeric when, as it is wont to do, SPSS imports some Excel fields as strings and some as numeric, with no obvious reason why.

The command is:

RECODE oldvar (CONVERT) INTO newvar .

Note that "newvar" has to be just that; you have to use a new variable name. Otherwise, you get this error:

>Error # 4686 in column 28. Text: hccc
>On the RECODE command, an attempt has been made to assign a numeric value
>to a string variable which is named after the keyword INTO.
>This command not executed.


If you're really fond of your original variable names, you could drop those variables and then do this:

RECODE newvar (ELSE=COPY) INTO oldvar.

Wednesday, February 14, 2007

Brief Big 5 scale, musical preferences scale

Some folks have a 10-item version of the Big 5 personality scale online that has been cross-validated, published, and translated into a number of languages. Impressive stuff. They're also the authors of STOMP, the Short Test of Music Preferences.

The instruments and a nice collection of supporting material are here.