Download Types of Inferential Statistics

Research Design & Analysis 2: Class 16
Announcements: Faculty job interviews
Ex-Post-Facto designs (continued)
• Breast cancer relative risks
A comparison of Prospective & Retrospective
data
• Review for Midterm
Colloquium Series: Job Candidate
Margo Watt
St. Francis Xavier
Learning History Origins of
Anxiety Sensitivity
Monday, March 13, 2000, 3:30 p.m.
HSH 202
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Psyc2023 Class#16 (c) Peter McLeod
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Lifetime Risks of
Developing
Breast Cancer
(US study
published in
Science ‘93)
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Top 10 Women’s
Cancers
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Incidence of
Breast Cancer
by Stage
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Incident & Mortality Rate Trends
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penny
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Relative Risk
Ratios for Breast
Cancer
* * * relative risk >4
* * relative risk of 2- 4
* relative risk of 1.1-1.9
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Putting risk of Breast Cancer in
Perspective
One woman in 9 in whom breast cancer will
develop, has a 50% chance of receiving
the diagnosis after age 65 and a 60%
chance of surviving that cancer and dying
of other causes
Risk of breast cancer in any given decade
never exceeds 1 in 34 (at 30 is 1 in 250)
Based on editorial in NEJM
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Cyclic Moods?
How many believe their moods
vary with:
• Days of the week?
• Lunar cycle?
• Menstrual cycle?
How would you study this?
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Psyc2023 Class#16 (c) Peter McLeod
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Raging female hormones in the courts
Macleans, June 15, 1981
Treatment for PMS ordered as stabber
put on probation
Globe and Mail, Feb 10, 1987
Women’s violence blamed on period
Toronto Star, August 25th 1978
Woman’s syndrome brings leniency
Vancouver Sun, February 10th, 1987
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Politics of PMS
• 1929 term “premenstrual tension” Dr.
Robert Frank
• Since 1970’s Dr. Katherine Dalton supports progesterone therapy
• estimates of prevalence 6-95%
• 150 somatic and psychological symptoms
associated with PMS
• According to some, PMS is a social and
political construct
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Hormonal
Changes
Over
Menstrual
Cycle
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Premenstrual Dysphoric Disorder Criteria
A: At least five of the following, present during last
week of luteal phase, remit within days of follicular
phase onset and absent week postmenses
(1) markedly depressed mood, feelings of
hopelessness. or self deprecating thoughts
(2) marked anxiety, tension, feelings of being "keyed
up.' or "on edge"
(3) marked affective lability, (e.g.. feeling suddenly
sad or tearful or increased sensitivity to rejection)
(4) persistent and marked anger or irritability or
increased interpersonal conflicts
(5) decreased interest in usual activities (e.g., work,
school, friends, hobbies)
5/24/2017
from
DSM IV
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Premenstrual Dysphoric Disorder Criteria
Continued:
(6) subjective sense of difficulty in concentrating
(7) lethargy, easy fatigability or marked lack of
energy
(8)marked change in appetite, overeating, or specific
food cravings
(9) hypersomnia or insomnia
(10) a subjective sense of being overwhelmed or out
of control
(11) other physical symptoms, such as breast
tenderness or swelling, headaches, joint or muscle
pain, a sensation of "bloating," Weight gain
from DSM IV
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Premenstrual Dysphoric Disorder Criteria
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Comparing Retrospective and
Prospective Data
Mood Fluctuations:
Women versus men and menstrual
versus other cycles
Jessica McFarland, et. al.
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McFarland et.al.
Methodological problems with existing
literature:
• demand characteristics (expectations of
participants, bias, volunteers)
• Measured negative moods (truncated
range)
• Retrospective reports
• No control groups
• No assessment of “normal” range of moods
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McFarland et.al.
Data suggest menstrual cycle related mood
effects are not an issue, yet the belief is there
Why?
• The methodological flaws mentioned
• Women believe they have menstrual mood
fluctuations when they do not.
Two questions of interest:
• Do women have classic cyclic mood
fluctuation?
• Are women’s moods more labile than men’s
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McFarland et.al.
Methods:
Studies both prospectively and retrospectively
Participants blind to purpose
Recorded moods for 70n days (at least 2 cycles)
3 groups: 1) normally cycling women, 2) women
on O.C.s and 3) men
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Mood grid
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Mood Pleasantness
Women: NC
Women: OC
Men
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Arousal Levels:
women only
concurrent vs.
retrospective reports
Concurrent reports
Retrospective reports
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Mood Pleasantness:
women only:
concurrent vs.
retrospective reports
Concurrent reports
Retrospective reports
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Mood Pleasantness
Ratings by days of
the Week
Concurrent reports
Retrospective reports
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Data on Prevalence of PMS Symptoms
• In surveys, most women report being more
emotional premenstrually
• With prospective studies, most women do
not show any relationship between mood
and “time of month”
• Of those who report PMS symptoms, only
50% actually have these mood fluctuations
• Significant positive correlation between a
woman’s belief in PMS prevalence and the
extent of her retrospective bias.
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Midterm Review
• Factorial Experiments: Advantages
• Factorial designs: terminology
– #levels IV1 x #levels IV2 x etc.
• Interpreting data from factorial experiments
and experiments with three or more levels of
one (ANOVA outputs & from data)
• Ex-post-facto designs: prospective and
retrospective designs - advantages
disadvantages
• Problems & Partial solutions:
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Midterm Review
• DVs used in Ex-post-facto studies
• Time-series designs, small-n designs
– A-B studies (e.g., homicides after prize
fights, JFK’s assassination etc.)
– multiple baseline designs
– non-equivalent control group
– replication within- and between-subjects
• reliability and generalizability
• Assessing external and ecological validity
• Volunteers
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