INTRODUCTION TO SCIENTIFIC PAPERS

INTRODUCTION TO
SCIENTIFIC PAPERS
Joe Pozdol, MLIS
Evans Whitaker, MD, MLIS
Norris Medical Library
University of Southern California
2003 Zonal Ave.
Los Angeles, CA 90089-9130
[email protected]
[email protected]
Before We Begin…
• Ask!
• PowerPoint at www.usc.edu/nml under
Key Resources for Students
• Interactive questions
• Handouts
• Article later
• Evaluation
• Unwanted handouts
Outline For Today
I. Parts of a paper
A. Abstract
B. Introduction/Background
C. Methods
D. Results
E. Discussion
F. References (Bibliography)
II. Study types
A. Primary
1. Observational
2. Experimental
B. Secondary
III. Group work
IV. Evaluations
PART I
SECTIONS OF A PUBLISHED
SCIENTIFIC PAPER
Part I Objectives
• Learn the basic structure of papers
• Develop an approach to reading papers
• Learn how to interpret an article citation
The Basic Parts
• Title
• Abstract
• Introduction
• Methods
• Results
• Discussion
• References
Read In This Order
• Title
• Abstract
• Introduction/
Discussion
• Methods/
Results
The discussion section occurs
before the author presents the
results of the study.
1. True
2. False
Which occurs first in a
scientific journal article?
1.
2.
3.
4.
5.
Abstract
Discussion
Introduction
Methods
Results
Abstract
•
•
•
•
Summarizes
Often only part read
Don’t act on abstracts alone
Structured abstracts are norm
– Background
– Methods
– Results
– Conclusions
Introduction
•
•
•
•
•
•
•
Context
What is known
Supporting literature (citations)
Gaps in literature
The research question
Newness
Relevance to field
Methods
• Steps taken to
– gather data
– analyze data
• Statistical methods
• Not a “cookbook”
• Replicable
Results
•
•
•
•
Report of data
Tables and graphs
Statistical results
No interpretation
Discussion
• Interpretation of results
• Answer to research question
• Goals met?
• Often includes
– relation to previous research
– limitations
– future directions
Which should allow other
researchers to replicate the study?
1.
2.
3.
4.
5.
Abstract
Discussion
Introduction
Methods
Results
Limitations of the study are
found in the…
1.
2.
3.
4.
5.
Abstract
Discussion
Introduction
Methods
Results
References
• List of sources cited in intro
• Usually other journal articles
• Previous studies in same field
• Citation styles differ depending on
– field of study (e.g. AMA vs. APA)
– journal
• EndNote and RefWorks
Understanding Journal Article
References
Weiss, PA. Does smoking marijuana contribute to the risk of developing
lung cancer? Clinical Journal of Oncology Nursing. 2008;12(3):517-519.
Journal
Volume Number
Issue Number
Researcher’s Article
Which cannot be determined
from a reference list citation?
1. Title of the journal
2. Title of the journal article
3. Number of pages in the
journal
4. Number of pages in the
journal article
5. None of the above
Whether marijuana use causes lung cancer
is still unknown and will likely be a subject of
research in the next 5 years.
1. True
2. False
PART II
TYPES OF SCIENTIFIC PAPERS
Part II Objectives
• Learn the common study types
• Be able to extract the research question
• Be able to identify an article’s study type
• Be able to determine the conclusions
Outline For This Section
• Focus on 4 study designs
o Case-control
o Cohort
o Randomized Control Trial
o Review
• Narrative
• Systematic
• Meta Analysis
“3 questions to get your bearings” *
1. What was the research
question?
2. What was the research design?
3. Was the research design
appropriate to the question?
Will try to find answers to 1 and 2 in
excerpts of 4 articles (A-D) provided
* - Greenhalgh, T. (2006). How to read a paper: the basis of evidence-based medicine.
Malden, MA: Blackwell
Study Designs
•Primary Literature
oObservational
• Case-Control
• Cohort
oExperimental
• Randomized Control Trial
•Secondary Literature
oNarrative
(Subject/Journalistic)
Reviews
oSystematic Review
oMeta Analysis
Case-Control
Patients with a disease or exposure
--compared to-Similar group without disease or exposure
• Best uses
o Rare conditions
o Diseases or conditions
time to develop
that may take a long
Background: DES
• Used in the United States from 1947 until 1971
• Boston area doctors noted an unusual cancer
• Study compared the group with the cancer to
similar people without the cancer
• The major difference between the cases and the
controls was DES exposure
Example: DES and Cancer
• Herbst, A.L., Ulfelder, H., & Poskanzer,D.C.
(1971). Adenocarcinoma of the vagina:
association of maternal stilbestrol therapy
with tumor appearance in young women.
NEJM, 284(16), 478-481.
• Look at article:
– Last sentence in Introductory area = research question
– First paragraph in methods = research design
Why did the authors match cases
and controls by the type of
service mothers received?*
To
de
ov
e
al
A
ll
o
ft
he
m
ic
ci
de
if
ch
e
w
he
am
in
e
ex
To
ab
...
..
rt
th
e
co
...
ci
oe
so
e
4.
du
c
3.
25% 25% 25% 25%
re
2.
* -see page 879
To reduce socioeconomic
differences
To examine whether the
cancer was related to
infectious disease exposures
To decide if chemical
disinfectants used to clean
wards caused cancer
All of the above
To
1.
Cohort
• Two groups compared over time
• One group with “exposure”,
the other without the “exposure”
• Best used:
o when exposures can’t be controlled
o when outcomes occur infrequently
o when RCT is not ethical
Example: Smoking vs. Non-Smoking
British Physicians
• Doll, R., Peto, R., Boreham, J., & Sutherland, I.
(2004). Mortality in Relation to Smoking: 50
years' observations on male British doctors.
BMJ, doi:10.1136/bmj.38142.554479.AE
• 50 years (and counting) Cohort Study of British
doctors
• Most recent of a series of reports
• Compared health outcomes of smokers vs.
health outcomes of non-smokers
• Research question =
• Research design =
When was there enough evidence from this
study to show the link between smoking and
lung cancer?
25%
25%
19
91
25%
19
78
25%
19
66
1954
1966
1978
1991
19
54
1.
2.
3.
4.
Randomized Control Trial
• A treatment group is compared to a
control group
• Group members are assigned randomly
• Best uses:
– Drug therapies
– Medical treatments
Example: Smoking cessation
intervention
• An, L.C., Klatt, C., Perry, C.L., Lein, E.B., Hennrikus,
D.J., et al. (2008). The RealU online cessation
intervention for college smokers: a randomized
control trial. Preventive Medicine, 47(2)194-199.
• Look at the article:
o The last paragraph of the introduction - research question
o The last paragraph of the introduction - research design
o Study flow chart - pg. 196
25,000 UM students were recruited by email
How many UM students ended up in the
intervention group?
1.
2.
3.
4.
5.
24,007
2,407
257
107
7
What percent of RealU participants had
30 days of no smoking at week 30?
30
ne
0%
no
%
0%
20
%
0%
40
60
80
0%
%
0%
%
0%
0%
100%
80%
60%
40%
20%
none
10
1.
2.
3.
4.
5.
6.
Narrative (Journalistic/Subject)
Reviews
• The “traditional” or “classic” review
• “Review” limit in Ovid/PubMed includes:
– Narrative reviews
– Systematic reviews
• Authors choose articles included
• Author bias is a concern – research
verifies this effect
Systematic Review
• Reproducible methods to find and select
articles are included
• Should include both inclusion and exclusion
criteria
• Why? Decrease author bias
Example: Is HPV Vaccine
Cost-Effective?
• Techakehakij, W., Feldman, R.D. (2008). Costeffectiveness of HPV vaccination compared to
Pap smear screening on a national scale: a
literature review. Vaccine,
doi:10.1016/j.vaccine.2008.09.036
• Look at article:
– Pg. 2, Section 3.1, first paragraph = research question
– Pg. 3, Section 4.1, first to third paragraphs =
research design
It is recommended that HPV vaccine be
given as a 3 shot series. How much do
3 doses of vaccine cost?
1.
2.
3.
4.
$500-$1000
$300-$500
$200-$300
$100-$200
30
0%
$500-$1000
0%
$300-$500
0%
$200-$300
0%
$100-$200
Meta Analysis
• Similar to Systematic Review except…
• Numeric data from separate studies
combined in meta analysis
• Uses statistical/mathematical methods to
combine numerical data from studies
• Combining data increases the confidence
we have in the conclusions reached by a
meta analysis
GROUP WORK
Group Work
• Groups of 3
• Everyone in group gets same article (#1, 2, 3, OR 4)
• Spend 10 min. working together on questions
• Class discussion
ADDITIONAL SLIDES
What kind of
question is it
good for?
Strengths
Weaknesses
Case-Control
(Herbst, 1971)
(Peled, 2008)
-Rare disorders or
conditions
-Slow developing
disorders
-Causation*
-Short time frame to
examine
correlations
between disorder
and other factors
-Susceptible to bias
-Limited validity
-Cross sectional
Cohort**
(Doll, et al, 2004)
(Metcalf, 2008)
- Prognosis
-Causation*
- Feasible when
studying conditions
or exposures over
which the
investigator has no
control
-Susceptible to bias
-Limited validity
-May require large
groups, long
durations, great
cost
-Longitudinal
-Usually
prospective
-Can be
retrospective (less
cost)
Randomized Control
Trial (RCT)
(An et al, 2008)
(Gordon, 1997)
-Drug treatment
-Medical
interventions
-Strong level of
evidence
-Low susceptibility
to bias
-Feasibility (e.g.
Ethical limitations)
-Generalizability**
-Randomization
method Experimental and
control groups
Systematic Review
(Techakehakij,2008)
(Gallicchio, 2008)
-Drug treatment
-Medical
interventions
-Low susceptibility
to bias
-Strongest level of
evidence
-Many topics have
no systematic
review
-Methods section
has explicit
information about
information
sources, how
articles were
chosen or excluded
Article Type
* - used loosely here; not distinguishing between correlation and causation
(in medicine etiology is used for the cause of a disease or condition)
** - can results of an RCT be applied to groups that do not match the study group?
Identifying
Characteristics
Thanks for your attention
• We will post these slides on the
Student Portal on the Norris Medical
Library website
• Contact us with questions
– Joe Pozdol – [email protected]
– Evans Whitaker – [email protected]
• Please complete evaluations!
References
•
•
•
•
•
•
An, L.C., Klatt, C., Perry, C.L., Lein, E.B., Hennrikus, D.J., et al.
(2008). The RealU online cessation intervention for college
smokers: a randomized control trial. Preventive Medicine,
47(2)194-199.
Doll, R., Peto, R., Boreham, J., & Sutherland, I. (2004). Mortality in
Relation to Smoking: 50 years' observations on male British
doctors. BMJ, doi:10.1136/bmj.38142.554479.AE
Gallicchio, L., Boyd, K., Matanoski, G., et al. (2008). Carotenoids
and the risk of developing lung cancer: A systematic review.
Am.J.Clin. Nutrit., 88, 372-383.
Gordon, C.M., Carey, M.P., & Carey, K.B. (1997). Effects of a
drinking event on behavioral skills and condom attitudes in
men: Implications for HIV risk from a controlled experiment.
Health Psychology, 16(5), 490-495.
Greenhalgh, T. (2006). How to read a paper: the basis of evidencebased medicine. Malden, MA: Blackwell.
Guyatt, G., Rennie, D. (eds.). (2001). User’s guides to the medical
literature: essentials of evidence-based clinical practice.
Chicago: AMA Press.
References
• Herbst, A.L., Ulfelder, H., & Poskanzer,D.C. (1971).
Adenocarcinoma of the vagina: association of maternal
stilbestrol therapy with tumor appearance in young women.
NEJM, 284(16), 478-481.
• Metcalf, B.S., Voss, L.D., Hosking, J., & Wilkin, J.T. (2008). Physical
activity at the government-recommended level and obesityrelatedhealth outcomes: a longitudinal study (Early Bird 37).
Archives of Diseases of Childhood (Early Bird 37). 93,722-777.
• Peled, R. Carmil, D., Siboni-Samocha, O., & Shoham-Vardi, I.
(2008). Breast cancer, psychological distress and life events
among young women. BMC Cancer, 8, 245-250.