Within-subjects design: all the participants are exposed to several conditions.
* This presentation only focuses on between-subject design.
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Data considerations
SPSS.
Байду номын сангаасelect Analyze
General Linear Model
Univariate
Move Q81
Move Q3r
Click Post Hoc
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Post Hoc Comparisons
This analyses assess mean differences between all combinations of pairs of groups (6 comparions)
By Hui Bian Office for Faculty Excellence
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One-way ANOVA with SPSS Two-way Factorial ANOVA with SPSS How to interpret SPSS outputs How to report results
The target population is high school students Multiple health behaviors include drinking, smoking,
exercise, eating habits, etc.
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ANOVA means Analysis of Variance ANOVA: compare means of two or more levels of the
Independent variable (factor variable) is categorical. Dependent variable should be quantitative (interval
level of measurement).
Assumptions
Independent: each group is an independent random sample from a normal population.
independent variable
One independent variable One dependent variable The basic test uses F distribution Comparing means is a special case of a regression
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Example:
Research design: between-subjects design Research question: Is there a difference in sedentary
behavior across four grade levels?
One independent variable: Grade with 4 levels: 9th, 10th, 11th, and 12th grade (Q3r).
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Options
In the Display box: check •Descriptive statistics •Estimate of effect size •Homogeneity test
Click Continue Then click OK
Normality: analysis of variance is robust to departures from normality, although the data should be symmetric.
Homogeneity: the groups should come from populations with equal variances.
One dependent variable: sedentary behavior (Q81: How many hours watch TV)
Higher score of Q81 = More hours on watching TV.
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Running a one-way between-subjects ANOVA with
If the F ratios for the independent variable is significant To determine which groups differ from which It is a follow-up analysis Check Tukey checkbox Click Continue
Independent variable 3
Error
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Research design
Between-subjects design*: different individuals are assigned to different groups (level of independent variable).
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We use 2009 Youth Risk Behavior Surveillance System (YRBSS, CDC) as an example.
YRBSS monitors priority health-risk behaviors and the prevalence of obesity and asthma among youth and young adults.
analysis
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The partitioning of the total sum of squares of deviations
Total sum of Squares of deviations of DV
Independent variable 1
Independent variable 2