Lecture Outline 1. Function of Introduction 2. Length 3. Parts 4. Examples How to write the introduction

Results Methods Introduction Discussion Motivate the reader! In hopes they will read the entire paper THROUGH the discussion Introduction Function

Function Why did you do this study? How does it compare to what is currently accepted? How are you going to do the study? Short summary of what you found = your main point (not in every journal) Ref: V. McMillan Intro

Why did you do it? Are you testing a hypothesis? –Do people who have had hepatitis B virus have a higher incidence of hepatitis C virus compared with people who have not had a HBV infection? Are you improving a method? –Faster, cheaper, more sensitive Are you performing a descriptive study? –Characterizing the distribution of dengue viral infection by geographic region

Length Keep it BRIEF See your target journal for average length of introduction Try to limit the introduction to 3 or 5 paragraphs

Results Methods Introduction Discussion Let’s dissect the introduction into parts.

Flow of Introduction Ref: M. Zeiger General Specific

Flow of Introduction Known Unknown Question Approach Structure your paragraphs

First paragraph 1.Very broad and general 2. Orients reader to importance of topic

First sentence “Mycobacterium tuberculosis is the causative organism of tuberculosis (TB) and produces 8 million new cases of TB annually.” “Dengue fever and its more severe form, dengue hemorrhagic fever/dengue shock syndrome, are considered among the most important and widespread reemerging infectious diseases in developing countries.”

Relationship to other studies 1. Summarize previous knowledge 2. Prepare the scene for your work Reveal gaps and holes Raise a question

–Make sure you have done your literature review. –DO NOT summarize your entire field! –However DO reference studies that helped you come up with YOUR question. Cite relevant studies ONLY!

State your question What specific hypothesis are you testing? What exact process are you describing? What method are you trying to improve?

How did you do study? BRIEFLY say this in 1 or 2 sentences. Examples- “In this study, we characterized M. tuberculosis genotypes in Delhi using DNA fingerprinting and oligotyping.” - “We assessed the prevalence of Hepatitis A virus in storm drains by RT-PCR.”

Introduction Hypothesis Paper Model Known: YY is very important. Unknown: YY is not well characterized for disease X; Question: thus, in this current study, we have characterized YY in 203 patients with acute cases of disease X. Approach: To do this, we have measured YY by Z methods. Known Unknown Q A

“The immune response to dengue virus infection is poorly defined. Previously published animal models of dengue virus infection have not characterized the immunological responses very extensively (Author, 2005). To characterize the primary immune response in mice infected with dengue virus serotype 2 strain, we employed two complementary approaches: first we measured…” Introduction outline Hypothesis paper Known Unknown Q A

Known: The current approach is YY (REF). Unknown: YY is limited because of A, B, and C. Method:Thus, we have developed ZZ, which has the following advantages: D, E, and F. Approach: To do this, we altered YY by doing X. Known Unknown Q A Methods Paper Model # 2

“The existing strain-typing methods based on dengue viral genetic differences are constrained by technical requirements or cost considerations and cannot be easily applied to investigate a dengue epidemic where it is occurring. In this report, we characterized a novel method, one-step PCR, and evaluate its use as a simple and rapid alternative for strain typing in endemic settings.” Known Unknown Q A Introduction Summary Methods paper

Last paragraph Most important paragraph of the introduction Many readers will only read this paragraph of your introduction Include your main finding (in most journals ---but not always) Content similar to:  Abstract  Parts of discussion

Introductions should: - motivate the reader! - summarize literature. - be as brief as possible. - go from general to specific.