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Beer, Puke, & Rubber Ducks
To do list
What is logistic regression?
Why would I use this?
Student affairs example
Sneak peak at next time
Number of people who have math or
stats related scar tissue?
Number of people who have opened
SPSS in the past 3 months?
Online folks, take the poll via twitter
Kirsten R. Brown, Ph.D.
UWL-SAA Teaching Presentation
What is logistic
A statistical method for analyzing
data where you have one or more
independent variables that you want
to use to determine an outcome
(dependent variable). The outcome
We can predict stuff!!! (And this is fun)
The stuff we want to predict is
dichotomous. There are only 2 possible
The dependent variable is also mutually
exclusive, everyone fits into 1 of those 2
outcomes (you can’t be both).
We are interested in the odds of a particular
Research question: What factors predict the likelihood that a
student will vomit in the residence hall elevator?
Dependent variable: Vomit ; Yes = 1 /No =0
Independent or control variables:
How much did the student drink?
Did the student eat dinner?
Is the student Male or Female?
What is the student’s body weight?
Has the student vomited in the elevator before?
What is the student’s GPA?
How old is the student?
Did the student combine alcohol with other drugs?
What floor does the student live on?
1. Say hello & get to know your data
2. Clean your data
3. Make variables/ re-code variables (if needed)
4. Check assumptions of logistic regression
Sample size , Multicollinerarity , Outliers
5. Run preliminary tests
Bi-variable correlations between each IDV & DV
6. Go play
Select variables based on- previous research, theory,
logic, and occasionally data mining
Build some models (this is where quant is just as
“messy” as qual!)
7. Think about your findings
Do they make sense?
Do they fit with / extend the literature?
What are the odds that:
with a 3.2 GPA
who lives on the 4th floor
and consumed 10 beers and 2 shots of vodka
ate a small dinner at 5 pm
has not vomited in the elevator before
and did not use other drugs
What factors best predict if an
institution will offer Autism
Spectrum Disorder (ASD)
Independent & Control Variables
# of students with ASD
# of disability resource staff
Diagram the Problem
Residence hall accommodations
Peer mentoring programs
Type of institution
But we only have 30 minutes and
we are not in a computer lab… so
This is the
point in class
The website has 2 videos that
show you how to run a logistic
regression in SPSS
Your handout has screen shots of
SPSS output with how to do a
SPSS How to Run a Logistic Regression
A look ahead
at next week
Why: Understanding the logic, helps you
understand what you are reading before
Because: We often get lost in the little
picture (e.g., SPSS output) and forget
about the big picture.
Kirsten R. Brown, Ph.D.
* Cartoons are by Larson, Gary (n.d.). The Far Side. http://www.thefarside.com/