PSC 47410: Data Analysis Workshop
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What’s the purpose of this exercise?
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The workshop’s research questions:
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Who supports war in America?
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How consistent is support for conflict across different types of war?
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Should we be considering other, related questions? If this project were to be
expanded, what could else we look at… how different groups change their
support over time, support for other types of conflict, varying patterns in other
societies
Will you want to do your research paper on work that builds on this workshop?
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You research paper assignment will ask you to either do a more complex paper
on public opinion and war or to test the power of various causes of war to
explain the outbreak of a conflict not considered in our class readings
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How would a research paper using Pew data be different than this assignment
with respect to its literature review and what methods you would need to use?
PSC 4000-level Stats Workshop
Where Do You Get Survey Data?
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Why are we looking at survey data from the Pew Foundation? How do we
download a dataset from Pew?
http://people-press.org/category/datasets/?download=20034647
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Why do we have to read the methodology sheet first (it’s boring, but critical)?
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What do we do with the questionnaire?
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How does scientific method work?: In theory and in the real world
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Can we operationalize our dependent variable(s)? Are there some
questions that we can use to identify who supports war?
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Do we have the independent variable(s) we need? Are there any questions
that identify characteristics (e.g., gender) that we expect to be correlated
with whether a person supports war?
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What specific hypotheses can we explore with our survey? What specific
relationships do we expect to find between our independent and
dependent variables?
PSC 4000-level
Stats Workshop
What Do You Need to Turn In?
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Your assignment has two components:
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The first asks you to complete several data assignments
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The second is an 1000-word analytical essay
The assignments related to SPSS ask you to:
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Recode and label both new variables and their response categories
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You will be asked to create dummy (1-0 value) variables. For example, you can use a
question asking about religion to create a new variable called “Catholic,” where all
Catholic respondents are coded 1 and all other respondents are coded zero
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Calculate descriptive statistics
 Mean (the average value of the response categories)
 Median (the middle value for all of your observations)
 Mode (the most common response if there’s no natural order to variable’s
response categories)
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Generate a bar graph
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Do a little bivariate data analysis using SPSS’s cross-tab routine
PSC 4000-level
Stats Workshop
Getting Started with SPSS
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Open your dataset with SPSS
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Open a new syntax file
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What are the four SPSS screens you will be working with?
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Data editor: Data view
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Data editor: Variable view
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The syntax file (Why is it WAY better than just pointing and
clicking all of the time? Why is this the ONLY file that you will
want to save in most cases? )
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The output file
PSC 4000-level
Stats Workshop
Recoding Data in SPSS
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Why do we need to recode?
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Need to drop refusals (but we want to be careful to think about what “don’t know
means… e.g. if someone doesn’t know that she’s a born-again Christian, she’s not one)
Variables may not measure constructs correctly, so we need to create different
categories that make sense
We’ll want to create dummy (0-1) variables
How do we recode?
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Use the point and click menus at the top of the data editor
Use the “Recode Into Different Variable” option
Select variable you want to recode
Tell SPSS how you want to recode the variable
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Name and label the new variable
Define values
Do not hit OK; instead, you want to paste command into syntax
Highlight the appropriate syntax and click the run (arrow) button
PSC 4000-level
Stats Workshop
Recoding Data: Step by Step Illustration
PSC 4000-level
Stats Workshop
Recoding Data: Step by Step Illustration
PSC 4000-level
Stats Workshop
Recoding Data: Step by Step Illustration
PSC 4000-level
Stats Workshop
Recoding Data: Step by Step Illustration
PSC 4000-level
Stats Workshop
Recoding Data: Step by Step Illustration
PSC 4000-level
Stats Workshop
Recoding Data: Step by Step Illustration
PSC 4000-level
Stats Workshop
Labeling Values in SPSS
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Why do we need to label the values used for different response
categories (e.g., 1=male, 0=woman)?
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You may not remember how you recoded values
Labels will transfer into tables and graphs
How do we label values for our variable categories?
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Use “Define Variable Properties” option
Select variable(s) with values you want to label
Tell SPSS how you want to label the values
Paste command into syntax
Highlight syntax and click run
Once you’ve got the syntax down, you may want to work much
more quickly with other variables by copying and pasting that
syntax and making appropriate substitutions
PSC 4000-level
Stats Workshop
Creating Value Labels for Response Categories:
Step by Step Illustration
PSC 4000-level
Stats Workshop
Creating Value Labels for Response Categories:
Step by Step Illustration
PSC 4000-level
Stats Workshop
Creating Value Labels for Response Categories:
Step by Step Illustration
PSC 4000-level
Stats Workshop
Creating Value Labels for Response Categories:
Step by Step Illustration
PSC 4000-level
Stats Workshop
Creating Value Labels for Response Categories:
Step by Step Illustration
PSC 4000-level
Stats Workshop
Descriptive Statistics in SPSS
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What descriptive statistics may interest us?
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Frequencies
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Mean (the average), Medians (the middle observation), and Mode (rarely
used)
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How do we compute descriptive statistics?
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Use “Descriptive Statistics” option
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Select “Frequencies”
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Select variable(s) that you want to analyze
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Select “Statistics”
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Select the statistics you want to view
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Option 1 (if you will need the results later): click the paste command to
create syntax; highlight the syntax and click run
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Option 2 (if you are using the results right now): click OK and the syntax
won’t be pasted into your syntax file, but the output will be created
PSC 4000-level
Stats Workshop
Descriptive Statistics: Step by Step Illustration
PSC 4000-level
Stats Workshop
Descriptive Statistics
PSC 4000-level
Stats Workshop
Descriptive Statistics: Step by Step Illustration
PSC 4000-level
Stats Workshop
Descriptive Statistics: Step by Step Illustration
PSC 4000-level
Stats Workshop
Descriptive Statistics: Step by Step Illustration
PSC 4000-level
Stats Workshop
Descriptive Statistics: Step by Step Illustration
PSC 4000-level
Stats Workshop
Descriptive Statistics: Step by Step Illustration
PSC 4000-level
Stats Workshop
Graphing in SPSS
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What kinds of graphs might we create?
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Bar
Line
Histogram
How do we compute descriptive statistics?
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Use “Descriptive Statistics” option
Select “Frequencies”
Select variable(s) that you want to analyze
Select “Charts”
Select the charts you want to view; check the “percentage” option in
most cases so that your charts will be more readable
Paste command into syntax
Highlight syntax and click run
PSC 4000-level
Stats Workshop
Creating Graphs
PSC 4000-level
Stats Workshop
Creating Graphs
PSC 4000-level
Stats Workshop
Creating Graphs
PSC 4000-level
Stats Workshop
Creating Graphs
PSC 4000-level
Stats Workshop
Creating Graphs
PSC 4000-level
Stats Workshop
Creating Graphs
PSC 4000-level
Stats Workshop
Creating Graphs
PSC 4000-level
Stats Workshop
Bivariate Analysis in SPSS
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What types of bivariate analysis might we conduct?
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Correlation
Crosstabs (this is your best option for tables that will make sense
to a general audience)
Significance tests
How do we conduct bivariate analysis?
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Use options in the “Analyze” menu
Select variable(s) that you want analyze
Tell SPSS how you want to analyze the values
Paste command into syntax
Highlight syntax and click run
PSC 4000-level
Stats Workshop
Calculating Correlation
PSC 4000-level
Stats Workshop
Calculating Correlation
PSC 4000-level
Stats Workshop
Calculating Correlation
PSC 4000-level
Stats Workshop
Calculating Correlation
PSC 4000-level
Stats Workshop
Calculating Correlation
PSC 4000-level
Stats Workshop
Guidelines for Correlation
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Less than .1: Very weak relationship
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.1 to .2: Weak relationship
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.2 to .3: Moderate relationship
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Above .4: Strong relationship
PSC 4000-level
Stats Workshop
Review: Variable Types
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Categorical
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Ordinal
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Represent categories or names (e.g. gender, religion)
Rank ordered indicators (e.g. agree, strongly agree)
Interval
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Ordered values where all unit increases are roughly
equivalent (e.g. age)
PSC 4000-level
Stats Workshop
Calculating Significance
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Crosstabs will allow you to see relationships between two
variables in more detail
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Put dependent variable in the rows
Put independent variable in the columns
Can also test association:
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Categorical/categorical: Lambda, Cramer’s V
Categorical/ordinal: Cramer’s V
Ordinal/ordinal: Gamma, Tau-B (same number of categories)
Categorical/Interval: Eta
Ordinal/Interval: Spearman’s Rho
Interval/Interval: Pearson’s R
PSC 4000-level
Stats Workshop
Crosstabs and Tests of Significance
PSC 4000-level
Stats Workshop
Crosstabs and Tests of Significance
PSC 4000-level
Stats Workshop
Crosstabs and Tests of Significance
PSC 4000-level
Stats Workshop
Crosstabs and Tests of Significance
PSC 4000-level
Stats Workshop
Crosstabs and Tests of Significance
PSC 4000-level
Stats Workshop
Crosstabs and Tests of Significance
PSC 4000-level
Stats Workshop
Crosstabs and Tests of Significance
PSC 4000-level
Stats Workshop
Crosstabs and Tests of Significance
PSC 4000-level
Stats Workshop