Taller de Redacción Científica

¿Cómo escribir los métodos?

Methods: 2-3 pages

Question: What did you do?

Purpose: Give enough detail for the study to be repeated.

Peat J et al

Methods What did you measured, what did

you do? In what order? Type of study (case series? rct?

descriptive? Methods paper?) Endpoints: primary and secondary Inclusion/exclusion criteria CONTROLS: selection Facilities available; facilities needed

Methods

Question: What did you do? Could a reader reproduce your study

based on the details you provide? Are the measurements described in a

logical order? Do you explain any sophisticated

analytic techniques and why you used them.

Methods Ethical approval Study design Participants: study population, how they were

selected, representative or not, samplying strategy.

Sample size calculations Questionnaires or other study instruments

(validated? Field tested? Standardized?) Interventions: How, when, by whom, where.

What was it done to control(s) (population/individuals).

Clinical assessments or evaluation methods Statistical methods

Methods Drugs: generic names, manufacturer,

concentrations/doses. Culture media: sources, concentrations,

types, incubation times and temperatures.

Study subjects: initial characteristics (age, gender, anthropometry, baseline charactestics) could be presented on a table in methods.

Methods

Read Journal instructions Allows reader to judge the quality

of the work Identifies weaknesses Allows repetition of the study State the study design Follow specific styles in clinical

trials, systematic reviews, etc.

Methods

I keep six honest serving-men(They taught me all I knew)Their names are WhatWhat and WhyWhy and

WhenWhenAnd HowHow and WhereWhere and WhoWho

“The Elephant’s Child” byRudyard Kipling (1865-1936)

Methods

WWWWWH Use sub-headings Define variables Patient inclusion Dates Randomisation Ethics/ consent Treatments Outcomes and endpoints Statistics and power: define variables, sample size and

assumptions, analytical procedures, statistical tests and selected p values for significant, normalization method, stratification, matching variables and methods, software used (version, source), etc.

Check list for Methods (1)

Study design mentioned? Who, what, where, why, how, when? Inclusion/exclusion criteria? (chrono)logical order? Measurements appropriate?

justified? detailed? referenced?

Check list for Methods (2)

Sample size justified? Transformations and stats

analyses clear? Any special features? New techniques validated

properly?

Check list for Methods (3)

Could the reader reproduce your study from the details provided?

Methods (4) Do not make the common error of mixing

some results into the methods section! If you are describing a new method,

describe it in detail. If you are using a previously published

method, you can use a reference, unless the reference is in a journal difficult to get. Then, describe the method and give the reference.

If a table or a figure may be effective in describing a method, use it and shorten the text.

Writing Tricks

Keep it simple Write for your readers not for your

mentors or sources or posterity Write first draft as though your

were explaining it to a layperson Add technical terms in second

draft.

Basic Rules of Writing Choose a suitable design and hold to it Use active voice Use the positive Omit needless words Use definite, specific, concrete language Make the paragraph the unit of

composition

Elements of Style. William Strunk, Jr

Active Voice

Active voice tells the reader who is doing what, thus, is easier to follow.

Passive

Passive:

“…ethical approval was obtained … charts were reviewed … subjects were analyzed … half were assigned … data was collected ….

Active

Active:

“ We searched … we identified … We then checked … we obtained ethical approval …”

Llewelyn CA p.417

Short vs Long

“Never use a long word where a short one will do.” – George Orwell

“the majority of” vs. “most” “prioritise” vs “rank” “utilize” vs “use” “in order to” vs “to” “in the event of” vs “if” or “when”

Short vs Long “for the reason that” vs “because” “due to the fact” vs “because” “on account of” vs “because” “owing to” vs “because” “on the basis that” vs “because”

Specific

“Any flu season will be accompanied by afflictions not due to influenza viruses.”

“Any flu season will be accompanied by respiratory infections not due to influenza viruses”.

Peat J

Put Statements in Positive Form

“…our findings were not dissimilar to …”

“…our findings were similar to …”

Paragraph

Use paragraph as unit of composition

One topic per paragraph

New topic, new paragraph

Topic sentence at the top

Topic Sentences: Page 429 Lipodystrophy (peripheral lipoatrophy,

central fat accumulation, and lipomatosis) affects at least 50% of HIV-1-infected adults receiving antiretroviral therapy…

Lipodystrophy is caused by some drugs within two of the four antiretroviral classes, namely …

The only proven intervention for HIV lipoatrophy is switching…” Carr A p.429

Short Sentences: 20-30 words

Test: Can you read them out loud without running out of breath?

Too long?

The effect of menopausal hormone-replacement therapy on breast cancer risk has been controversial for decades, controversy which will likely escalate as a result of the early termination of the randomized Hormone Replacement Therapy after Breast Cancer Diagnosis—Is It Safe? (HABITS) study, from Sweden.

Cut It Up

The effect of menopausal hormone-replacement therapy on breast cancer risk has been controversial for decades. The results of Hormone Replacement Therapy after Breast Cancer Diagnosis—Is It Safe? (HABITS) study are likely to escalate that controversy. This randomised trial from Sweden…

Short Sentences Can Do the Job

Mycobacterium tuberculosis has re-emerged as a major public-health threat.

Instead of being eradicated, drug-resistant strains have evolved and have been documented in every country surveyed.

Once a strain of M tuberculosis develops resistance to isoniazid and rifampicin, it is defined as multidrug-resistant tuberculosis (MDR-TB).

Mukherjee et al p.474

Revision

Writing is rewriting Put the manuscript away for a day

or more and come back to it fresh When you reread it, read it out

loud.

Revision: Organisation

Review and revise the large elements

Do you have all the elements? Are they all in the right order? Consult your checklists

Revision: Paragraphs

Does each major topic have its own paragraph?

Is there a clear topic sentence at the top of each paragraph?

Can a long paragraph be broken up into logical subtopics?

Is the sequence of the sentences within the paragraphs logical?

Topic Sentence: At the top

Two reports in today’s Lancet advance knowledge of the transmission and distribution of prions, the infectious agent causing transmissible spongiform encephalopathies.

More…

“Prions are devoid of informational nucleic acids and are thought to consist of an “infectious” protein (PrPSc) that can convert the normal host protein (PrPc) into a likeness of itself.”

And a bit more …

“Although not highly contagious, Creutzfeld-Jakob disease (CJD) has long been known to be transmissible.”

And so on …

“Variant CJD (vCJD) is probably caused by infection of human beings by …”

Revision: Sentences

Read your prose out loud. Can you finish each sentence on

one breath? Are your sentences simple and

direct? Look carefully at long sentences Look at sentence length variety

Is it more than one sentence?

“When you become hopelessly mired in a sentence, it is best to start fresh, do not try to fight your way through against the terrible odds of syntax.”

William Strunk, Jr

Spoon feed

Do not flood your reader with information faster than he or she can absorb it.

Kill Your Babies

If there is a sentence that you are particularly proud of, that seems to you to be particularly well crafted, that really “sings” – delete it.

Good Prose

“Prose is bad when people stop to look at it.”

T E Lawrence

Who-do Keep subject and verb close together

“Critics of the placing of any extra barrier between regulatory approval and prescribing argue that it is rationing by stealth.”

Critics argue that placing additional barriers between regulatory approval and prescribing is rationing by stealth.

Who-do Four further studies—which could be

difficult or even unethical in primary-care services that were being swamped by demands for zanamivir for suspected ‘flu’ —are now underway.

Four further studies are now underway. Studies that would be difficult or even unethical in primary-care services that were being swamped by demands for zanamivir for suspected “flu”.

Nominalizations

Nominalization: Making a verb into a noun

We conducted an investigation… We investigated…

We conducted a review of … We reviewed …

Use Signposts

Signposts help keep your readers on track

“First … second … third …” “On the other hand…” “By contrast, …” “In some cases, however …” “Therefore…” “ In summary,…”

Keep related words together “New York’s first commercial human-sperm

bank opened Friday with semen samples from 18 men frozen in a stainless steel tank.”

“New York’s first commercial human-sperm bank opened Friday when semen samples were taken from 18 men. The samples were then frozen and stored in a stainless steel tank.”

Strunk W

Related items together Keep positives together and negatives together

“Subjects with myocardial infarction were less likely to be married, older, drank less alcohol, were better educated, and were more likely to smoke.

“Subjects with myocardial infarction were older, better educated, and more likely to smoke and drink. They were less likely to be married or to drink alcohol.”

Browner

Comparisons Keep comparisons together – Browner

“There were more cases of esophageal cancer in our follow-up study of patients with Barrett’s esophagus than there were cases of gastric cancer”

“In our follow-up study of patients with Barrett’s esophagus, there were more cases of esophageal cancer than there were cases of gastric cancer.

Respectively Respectively means: “You figure it out.”

“The rates in the four groups (young men and women, older men and women) were 10%, 13%, 8%, and 21%, respectively”

“The rates were 10% in young men, 13% in young women, 8% in older men, and 21% in older women.”

Needless Words

A majority of most a number of several at this point in time now despite the fact that although has the capability of can in order to to with regard to about

Some Games to Play

Write without using the verb to be. Edit something you wrote –

reducing your word length by half. Better?

When you read something that strikes you as well written, analyze it. Topic sentences? Signposts? Sentence structure?

“Short, meaty, and clear”

“Think of yourself as a reader for a moment. What kind of papers do you like to read? Short, meaty, and clear most likely. Well, then, write short, meaty, and clear papers yourself.

” Mimi Zeiger.

What editors look for

Short, clear, precise title Good abstract Good design and methods Clear conclusions Brevity Follow instructions

What reviewers look for

Good design and methods Simple tables and figures Logical organisation Brevity Balance Appropriate statistics Their papers

What was written…what it means?

It has long been known… A definite trend is evident…

Of great theoretical importance…

While it has not been possible to provide definite answers…

Three groups were chosen for detailed study…

Typical results are shown… It is believed that… It is generally believed that… A careful analysis of available

data… Thanks are due to John B for

assistance with the experiments and to Jose G for valuable discussion

I didn’t look up the reference There was no statistical

significance

Interesting to me An unsuccessful experiment,

but I hope to get it published The other results were less

clear

The best result is I think My colleague thinks so too I lost some data John B did the work; Jose G

explained what it meant

Useful Books Scientific Writing: Easy when you know

how. Peat J et al. London. BMJ Books. 2002

Writing and Publishing in Medicine, 3rd Ed. Edward J Huth. Baltimore Maryland. Williams & Wilkins. 1999.

Publishing and Presenting Clinical Research. Warren S Browner. Baltimore Maryland. 1999. Williams & Wilkins.

Essentials of Writing Biomedical Research Papers. Mimi Zeiger. New York. McGraw-Hill. 2nd Edition, 2000.