johnfulwider.com | polisci


Factor Analysis Primer

Written by johnfulwider on March 8th, 2007
A colleague recommended this online primer on factor analysis, which uses international relations as its case study.
clipped from www.hawaii.edu
ANALYSIS

By way of orientation, the first section of this paper will present a brief conceptual review of factor analysis. In the second section the scientific context of the method will be discussed. The major uses of factor analysis will be listed and its relation to induction and deduction, description and inference, causation and explanation, and classification and theory will be considered. To aid understanding, the third section will outline the geometrical and algebraic factor models, and the fourth section will define the factor matrices and their elements–the vehicles for presenting factor results. Since comprehending factor rotation is important for interpreting the findings, the fifth and final section is devoted to clarifying its significance.

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Survey design tips — detailed yet readable

Written by johnfulwider on February 19th, 2007

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)

Convert string variables to numeric using SPSS syntax

Written by johnfulwider on February 18th, 2007

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.

Brief Big 5 scale, musical preferences scale

Written by johnfulwider on February 14th, 2007

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.

Quizlet - “The End of Flashcards” - and Comps Studying

Written by johnfulwider on January 29th, 2007

Flashcards

I’ve been looking for a place to share my ginormous stack of political science comprehensive exam flashcards (see above) with the world, and I just found it. Quizlet, a free service written by a high-schooler, lets you type in flashcards or import them from a spreadsheet. You can take some pretty snazzy quizzes online, share the flashcards with others, and print them out. Schnazzy.

I think what I’ll do when it comes time to study for Ph.D. comps (in about a year) is type in all my master’s comp flashcards, and in so doing study and do something nice for others at the same time. (At Nebraska, we have to take comps twice.)

(Via Lifehacker)

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