INTRODUCTION TO SCIENTIFIC PAPERS

Joe Pozdol, MLISEvans Whitaker, MD, MLIS

Norris Medical LibraryUniversity of Southern California

2003 Zonal Ave.Los Angeles, CA 90089-9130

pozdol@usc.edu ewhitake@usc.edu

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 ISECTIONS 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. Abstract

2. Discussion

3. Introduction

4. Methods

5. 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. Abstract

2. Discussion

3. Introduction

4. Methods

5. Results

Limitations of the study are found in the…

1. Abstract

2. Discussion

3. Introduction

4. Methods

5. 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 IITYPES 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 designsoCase-controloCohortoRandomized Control TrialoReview

• 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 LiteratureoObservational

• Case-Control• Cohort

oExperimental• Randomized Control Trial

•Secondary LiteratureoNarrative (Subject/Journalistic) ReviewsoSystematic ReviewoMeta Analysis

Case-ControlPatients with a disease or exposure

--compared to--Similar group without disease or exposure

•Best uses o Rare conditions o Diseases or conditions that may take a long

time to develop

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?*

25% 25%25%25%

* -see page 8791. To reduce socioeconomic differences

2. To examine whether the cancer was related to infectious disease exposures

3. To decide if chemical disinfectants used to clean wards caused cancer

4. All of the above

Cohort

• Two groups compared over time

• One group with “exposure”, the other without the “exposure”

• Best used:owhen exposures can’t be controlledowhen outcomes occur infrequentlyowhen 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%25%25%

1. 1954

2. 1966

3. 1978

4. 1991

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 questiono The last paragraph of the introduction - research designo Study flow chart - pg. 196

25,000 UM students were recruited by emailHow many UM students ended up in the

intervention group?

1. 24,007

2. 2,407

3. 257

4. 107

5. 7

What percent of RealU participants had 30 days of no smoking at week 30?

0% 0% 0%0%0%0%

1. 100%

2. 80%

3. 60%

4. 40%

5. 20%

6. none

30

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). Cost-effectiveness 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?

$500-$1000 $300-$500 $200-$300 $100-$200

0% 0%0%0%

1. $500-$1000

2. $300-$500

3. $200-$300

4. $100-$200

30

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

Article TypeWhat kind of question is it

good for?Strengths Weaknesses

Identifying Characteristics

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

* - 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?

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 – pozdol@usc.edu– Evans Whitaker – ewhitake@usc.edu

• 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 evidence-based 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 obesity-relatedhealth 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.