Lecture 1, PL2131, Mike Cheung 2011-12 1
1. GETTING STARTED: INTRODUCTION
It is easy to lie with statistics, but easier to lie without them. - Frederick Mosteller
Assigned readings: Chapter 1 and Chapter 5 (pp. 139-149) of Christensen, Johnson, and Turner
Chapter 1:
Displaying the
Order in a Group of
Numbers
Textbooks
Statistics for Psychology: International Edition, 6e
Research Methods, Design, and Analysis, Global
Edition, 12e
American Psychological Association (APA)
Publication Manual, 6e
1
Purchase Sta
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Chapter 2: Central
Tendency and
Variability
Notations in Statistic
Precision vs. intelligibility
n
X
i 1
i
X 1 X 2 X 3 X 4 . X n
vs
vs.
X
Rule of summation
( X Y ) X Y
( X C ) X nC
CX C X
1
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Measures of Central Tendency
Mean
Mode
Chapter 8:
t test for
Independent
Means
t Test for Independent Means
Comparing two samples
e.g., experimental and control group
Scores are independent of each other
1
populations
M1 M 2
M1 M 2
distributions
of means
M1 M 2
distribution of
differences betw
Chapter 6:
Making Sense of
Statistical
Significance:
Decision Errors,
Effect Size
&
Statistical Power
Decision Errors
Type I error
Reject the null hypothesis when in fact it is true
alpha ()
o
o
Probability of making a Type I error
It is the conventional
Chapter
5:
h
Hypothesis Tests
with Means of
Samples
The Distribution of Means
Sampling distribution
a distribution of a statistics with repeated sampling
Distribution of means
Distribution of the means of each of a very large number
of samples of the same
Chapter
4:
h
Introduction to
Hypothesis
Testing
Inferential Statistics
Involve making inferences about populations based
on information from samples (as compared to
d
descriptive
statistics, which
h h merely
l summarize
known information)
Especially impor
Chapter
7:
h
Introduction to
t Tests
Z test Example (chapter 5)
Evaluate the effectiveness of a new stressstressreduction program. Its known that NUS students
h
have
a stress level
l
l off 85
8 with
h a SD
S off 15, and
d the
h
stress levels are normally
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WELCOME TO PL2131
OUTLINE
Accessing PsycInfo
Formulating hypotheses
Research designs: Experimental and Nonexperimental
i
l
1
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PSYCINFO
Simply type lib.nus.edu.sg, click on Databases tab,
select PsycInfo.
Practices
Buss, D. M. (1995)
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WELCOME TO PL2131
OUTLINE
Control techniques
Constructing experimental designs
APA Format
1
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CONTROL TECHNIQUES
1. _
EV are jjustt controlled,
t ll d which
hi h means th
thatt
there could still be a overall effect of
EV on DV.
2. _
E
INFORMATION SHEETS
Guidance for Institutional Review Boards and Clinical Investigators
1998 Update
Appendix F
The Belmont Report
Ethical Principles and Guidelines for
the Protection of Human Subjects of Research
The National Commission for the Protection
Chapter 3:
Some Key
Ingredients for
Inferential
Statistics
Z Scores
Review: what is standard deviation?
Z score:
Formula?
Meaning?
(X M )
Formula: Z SD
Meaning: number of standard deviations a score is above
or below the mean
Wh t ffor?
What
From a Z scor
Lecture 3, PL2131, Mike Cheung 2011-12 1
3. SCIENTIFIC METHODS II: EXPERIMENTAL DESIGN
Experimental designs serve not only to relate variables to their effects, but also to rule
out alternative explanations in which the variables are said to be confounded
Lecture 2, PL2131, Mike Cheung 2011-12 1
2. SCIENTIFIC METHODS I: NON-EXPERIMENTAL DESIGN
Because controlled observation involves special procedures, uncontrolled observation, in
which the observers exerts no control over the situation and merely takes no
Lecture 4, PL2131, Mike Cheung 2011-12 1
4. DESCRIPTIVE AND INFERENTIAL STATISTICS
The process of drawing conclusions about a population on the basis of samples drawn
randomly from the population is statistical inference (Corsini & Auerbach, 1998, p.857).
Lecture 6, PL2131, Mike Cheung 2011-12 1
6. EFFECT SIZE AND STATISTICAL POWER
The statistical power of a significance test is the long-term probability, given the
population effect size, , and N of rejecting H0 (Cohen, 1992, p. 156).
Assigned reading: Cha
Lecture 5, PL2131, Mike Cheung 2011-12 1
5. HYPOTHESIS TESTING
Hypothesis testing is a procedure for deciding whether the outcome of a study (results for
a sample) support a particular theory or practical innovation (which is thought to apply to
a populat
Lecture 7, PL2131, Mike Cheung 2011-12 1
7. SAMPLING DISTRIBUTION OF MEANS
The distribution of means is the correct comparison distribution when there is more than
one person in a sample (Aron, Aron, & Coups, 2009, p.138).
Assigned reading: Chapter 5 of A
Lecture 12, PL2131, Mike Cheung 2011-12 1
12. RESEARCH ETHICS AND REPORT WRITING
Your study may have answered a very significant research question, but the results are of
no value unless they are made public (Christensen, Johnson, and Turner, 2010, p. 464
Lecture 9, PL2131, Mike Cheung 2011-12 1
9. INDEPENDENT SAMPLE T TEST
An independent sample t test is a hypothesis-testing procedure in which there are two
separate groups of people tested and in which the population variance is not known
(Aron, Aron, & C
1.
How many males are there who are working between 3 to 5 hours
and has income equal or less than 250?
Answer: 4 males
2.
Which group has a higher mean SWLS? Those with 0 working hours
or those with more than 0 working hours?
Answer: Those not working ha
Lecture 11, PL2131, Mike Cheung 2011-12 1
11. CHI-SQUARE TESTS
Chi-square tests are hypothesis-testing procedures used when the variables of interest
are nominal variables (Aron, Aron, & Coupos, 2009, p. 536).
Assigned reading: Chapter 13 of Aron, Aron, a
Lecture 8, PL2131, Mike Cheung 2011-12 1
8. ONE SAMPLE AND DEPENDENT SAMPLE T-TEST
A t test for a single sample is a hypothesis-testing procedure in which a sample mean is
being compared to a known population mean and the population variance is unknown
(A
Lecture 10, PL2131, Mike Cheung 2011-12 1
10. CORRELATION AND SIMPLE REGRESSION
A correlation describes the relationship between two [interval] variables (Aron, Aron,
& Coupos, 2009, p. 433).
Assigned readings: Chapters 11 and 12, and pp. 618-620 of Aron,
Semester 2, 2015-2016
PL2131 Research and Statistical Methods I
The Last Lecture
The Last Lecture
LIM Wee Hun Stephen, Ph.D.
Department of Psychology
National University of Singapore
Lecture Overview
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