PSYC 6130
Lecture 17: Multiple Comparisons
Lecture 17 Summary
Why do multiple comparisons
The problem with multiple comparisons
Familywise and per-comparison alpha
Exploratory data analysis
Fishers pr
Even More Alternatives to the
Two Independent Samples t
Summary of Available Procedures
(up to now)
Equal variances, normal distributions:
Two independent samples t
Even better would be the Welch t
Testing for Mean Differences
Under Nonnormality
Normality Assumption
In computing Students t, we need to assume
that the populations from which our groups were
sampled are normal in form
When the di
Final exam notes
Partitioning the
Variability
In a one-way design we
partitioned the variability
into: SStotal = SSbetween + SSwithin
1
2
3
In a two-way design: SStotal =
SS + SS + SS+ SSwithin
4
Wher
Midterm exam notes
Partitioning the Variability
In a one-way design we partitioned the
variability into: SStotal = SSbetween + SSwithin
1
2
3
In a two-way design: SStotal = SS + SS +
SS+ SSwithin
4
Wh
PSYC 6130 - UNIVARIATE ANALYSIS
Lab Exercise #12
1) A researcher is interested in attitudes towards socialized medicine before and after a
pro-socialized medicine talk. Specifically, the researcher wo
Simple Correlation &
Regression
Review of Correlation and
Regression
A large proportion of psychological research
explores relationships among variables, as
opposed to exploring mean differences in
v
Simple Linear Regression
Linear Regression
Predicting Y from X
Recall that the equation for a straight line is:
Y = a + bX
We can also write the prediction equation as:
Y = a + bX
Where:
Y is th
Univariate Statistics
A Review of Preliminary Concepts
Population/Sample
Population: the entire set of events (e.g.,
university students) to which you are
interested
Sample: a subset of the populati
Standard Assumptions
When we think of traditional parametric tests for
independent groups designs, the following
assumptions are required:
Normal distributions in each of the populations
Equal vari
PSYC 6130 - UNIVARIATE ANALYSIS
ASSIGNMENT #1
Due Date: October 22, 2013 (11:59 pm)
[Submit by hardcopy or email to both Phil and Rob]
Use R Markdown for questions 2 and 3 and submit the html file. An
PSYC 6130 - Univariate Analysis
Class Assignment #4
Question 1:
Dr. Smith believes that she can reduce statistics anxiety in a Department of Psychology
Introductory Statistics course by spending time
Comparisons/Contrasts of
Group Means
Introduction
Ho: 1= 2 = . = k can be tested using a oneway ANOVA and tests the null hypothesis of no
difference between ANY means
However:
Researchers are usual
Factorial Designs
Introduction to Two-Way
Independent Groups Models
Part 2
Should we Always Analyze
Interactions in Factorial Models
The issue of not including interaction terms in
models arises when
Factorial Designs
Introduction to Two-Way
Independent Groups Models
Introduction
Dr. Black would like to determine if the sex of
a subject, or the size of the community in which
the subject was raise
Multiple Regression
Multiple Regression
Multiple regression extends linear regression to allow for
2 or more independent variables.
There is still only one dependent (criterion) variable.
We can th
Linear Correlation
Perfect Correlation
2 variables x and y are perfectly correlated if they are
related by an affine transform
y = ax + b
The correlation is positive if a>0 and negative if a<0.
By
Probability, Bayes Theorem
and the Monty Hall Problem
Probability Distributions
A random variable is a variable whose value is uncertain.
For example, the height of a randomly selected person in this
PSYC 6130
One-Way Independent ANOVA
Generalizing t-Tests
t-Tests allow us to test hypotheses about differences
between two groups or conditions (e.g., treatment and
control).
What do we do if we wis
Two-Way (Independent) ANOVA
Two-Way ANOVA
Two-Way means groups are defined by 2 independent
variables.
These IVs are typically called factors.
An experiment in which any combination of values for
t
Introduction to Hypothesis Testing
The One-Sample z Test
The One-Sample z Test
Conditions of Applicability:
One group of subjects
Comparing to population with known mean and variance.
Note: this i
Beyond Null Hypothesis Testing
Supplementary Statistical Techniques
Limitations of NHT
Criticisms of NHT date from the 1930s.
Null hypothesis is rarely true.
The real question is not about the exis
(One-Way) Repeated Measures ANOVA
One-Way Repeated Measures ANOVA
Generalization of repeated-measures t-test to
independent variable with more than 2 levels.
Each subject has a score for each level
t-Tests
Interval Estimation and the t Distribution
Large Sample z-Test
Sometimes we have reason to test hypotheses involving specific
values for the mean.
Example 1. Claim: On average, people sleep l
STUDY GUIDE FOR THE COURSE
Partitioning the
Variability
In a one-way design we
partitioned the variability
into: SStotal = SSbetween + SSwithin
1
2
3
In a two-way design: SStotal =
SS + SS + SS+ SSwit
An extension of ANOVA in which the effects
of the IV on the DV are assessed after the DV
has been adjusted for by the DVs
relationship with one or more covariates
A covariate is a variable that is re
PSYC 6130 - UNIVARIATE ANALYSIS
Lab Exercise #15
Two researchers, one from Canada, and one from the US, were interested in exploring the
relationship between level of repentance and level of forgivene
PSYC 6130 - Univariate Analysis
Class Assignment #3
Question 1
Dr. Dermott is interested in determining how the sex and grade of elementary school children
relate to confidence in math ability and rea