C material y método


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C material y método

  1. 1. Taller de Redacción Científica ¿Cómo escribir los métodos?
  2. 2. Methods: 2-3 pages <ul><li>Question: What did you do? </li></ul><ul><li>Purpose: Give enough detail for the study to be repeated. </li></ul><ul><ul><li>Peat J et al </li></ul></ul>
  3. 3. Methods <ul><li>What did you measured, what did you do? In what order? </li></ul><ul><li>Type of study (case series? rct? descriptive? Methods paper?) </li></ul><ul><li>Endpoints: primary and secondary </li></ul><ul><li>Inclusion/exclusion criteria </li></ul><ul><li>CONTROLS: selection </li></ul><ul><li>Facilities available; facilities needed </li></ul>
  4. 4. Methods <ul><li>Question: What did you do? </li></ul><ul><ul><li>Could a reader reproduce your study based on the details you provide? </li></ul></ul><ul><ul><li>Are the measurements described in a logical order? </li></ul></ul><ul><ul><li>Do you explain any sophisticated analytic techniques and why you used them. </li></ul></ul>
  5. 5. Methods <ul><li>Ethical approval </li></ul><ul><li>Study design </li></ul><ul><li>Participants: study population, how they were selected, representative or not, samplying strategy. </li></ul><ul><li>Sample size calculations </li></ul><ul><li>Questionnaires or other study instruments (validated? Field tested? Standardized?) </li></ul><ul><li>Interventions: How, when, by whom, where. What was it done to control(s) (population/individuals). </li></ul><ul><li>Clinical assessments or evaluation methods </li></ul><ul><li>Statistical methods </li></ul>
  6. 6. Methods <ul><li>Drugs: generic names, manufacturer, concentrations/doses. </li></ul><ul><li>Culture media: sources, concentrations, types, incubation times and temperatures. </li></ul><ul><li>Study subjects: initial characteristics (age, gender, anthropometry, baseline charactestics) could be presented on a table in methods. </li></ul>
  7. 7. Methods <ul><li>Read Journal instructions </li></ul><ul><li>Allows reader to judge the quality of the work </li></ul><ul><li>Identifies weaknesses </li></ul><ul><li>Allows repetition of the study </li></ul><ul><li>State the study design </li></ul><ul><li>Follow specific styles in clinical trials, systematic reviews, etc. </li></ul>
  8. 8. Methods <ul><li>I keep six honest serving-men </li></ul><ul><li>(They taught me all I knew) </li></ul><ul><li>Their names are What and Why and When </li></ul><ul><li>And How and Where and Who </li></ul>“ The Elephant ’ s Child ” by Rudyard Kipling (1865-1936)
  9. 9. Methods <ul><li>WWWWWH </li></ul><ul><li>Use sub-headings </li></ul><ul><li>Define variables </li></ul><ul><li>Patient inclusion </li></ul><ul><li>Dates </li></ul><ul><li>Randomisation </li></ul><ul><li>Ethics/ consent </li></ul><ul><li>Treatments </li></ul><ul><li>Outcomes and endpoints </li></ul><ul><li>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. </li></ul>
  10. 10. Check list for Methods (1) <ul><li>Study design mentioned? </li></ul><ul><li>Who, what, where, why, how, when? </li></ul><ul><li>Inclusion/exclusion criteria? </li></ul><ul><li>(chrono)logical order? </li></ul><ul><li>Measurements appropriate? justified? detailed? referenced? </li></ul>
  11. 11. Check list for Methods (2) <ul><li>Sample size justified? </li></ul><ul><li>Transformations and stats analyses clear? </li></ul><ul><li>Any special features? </li></ul><ul><li>New techniques validated properly? </li></ul>
  12. 12. Check list for Methods (3) <ul><li>Could the reader reproduce your study from the details provided? </li></ul>
  13. 13. Methods (4) <ul><li>Do not make the common error of mixing some results into the methods section! </li></ul><ul><li>If you are describing a new method, describe it in detail. </li></ul><ul><li>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. </li></ul><ul><li>If a table or a figure may be effective in describing a method, use it and shorten the text. </li></ul>
  14. 14. Writing Tricks <ul><li>Keep it simple </li></ul><ul><li>Write for your readers not for your mentors or sources or posterity </li></ul><ul><li>Write first draft as though your were explaining it to a layperson </li></ul><ul><li>Add technical terms in second draft. </li></ul>
  15. 15. Basic Rules of Writing <ul><ul><li>Choose a suitable design and hold to it </li></ul></ul><ul><ul><li>Use active voice </li></ul></ul><ul><ul><li>Use the positive </li></ul></ul><ul><ul><li>Omit needless words </li></ul></ul><ul><ul><li>Use definite, specific, concrete language </li></ul></ul><ul><ul><li>Make the paragraph the unit of composition </li></ul></ul><ul><ul><ul><li>Elements of Style. William Strunk, Jr </li></ul></ul></ul>
  16. 16. Active Voice <ul><li>Active voice tells the reader who is doing what, thus, is easier to follow. </li></ul>
  17. 17. Passive <ul><ul><li>Passive: </li></ul></ul><ul><ul><ul><li>“… ethical approval was obtained … charts were reviewed … subjects were analyzed … half were assigned … data was collected …. </li></ul></ul></ul>
  18. 18. Active <ul><li>Active: </li></ul><ul><ul><li>“ We searched … we identified … We then checked … we obtained ethical approval …” </li></ul></ul><ul><ul><li>Llewelyn CA p.417 </li></ul></ul>
  19. 19. Short vs Long <ul><li>“ Never use a long word where a short one will do.” – George Orwell </li></ul><ul><ul><li>“ the majority of” vs. “most” </li></ul></ul><ul><ul><li>“ prioritise” vs “rank” </li></ul></ul><ul><ul><li>“ utilize” vs “use” </li></ul></ul><ul><ul><li>“ in order to” vs “to” </li></ul></ul><ul><ul><li>“ in the event of” vs “if” or “when” </li></ul></ul>
  20. 20. Short vs Long <ul><ul><li>“ for the reason that” vs “because” </li></ul></ul><ul><ul><li>“ due to the fact” vs “because” </li></ul></ul><ul><ul><li>“ on account of” vs “because” </li></ul></ul><ul><ul><li>“ owing to” vs “because” </li></ul></ul><ul><ul><li>“ on the basis that” vs “because” </li></ul></ul>
  21. 21. Specific <ul><li>“ Any flu season will be accompanied by afflictions not due to influenza viruses.” </li></ul><ul><li>“ Any flu season will be accompanied by respiratory infections not due to influenza viruses”. </li></ul><ul><li>Peat J </li></ul>
  22. 22. Put Statements in Positive Form <ul><li>“… our findings were not dissimilar to …” </li></ul><ul><li>“… our findings were similar to …” </li></ul>
  23. 23. Paragraph <ul><li>Use paragraph as unit of composition </li></ul><ul><ul><li>One topic per paragraph </li></ul></ul><ul><ul><li>New topic, new paragraph </li></ul></ul><ul><ul><li>Topic sentence at the top </li></ul></ul>
  24. 24. Topic Sentences: Page 429 <ul><li>Lipodystrophy (peripheral lipoatrophy, central fat accumulation, and lipomatosis) affects at least 50% of HIV-1-infected adults receiving antiretroviral therapy… </li></ul><ul><li>Lipodystrophy is caused by some drugs within two of the four antiretroviral classes, namely … </li></ul><ul><li>The only proven intervention for HIV lipoatrophy is switching…” Carr A p.429 </li></ul>
  25. 25. Short Sentences: 20-30 words <ul><li>Test: Can you read them out loud without running out of breath? </li></ul>
  26. 26. Too long? <ul><li>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. </li></ul>
  27. 27. Cut It Up <ul><li>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… </li></ul>
  28. 28. Short Sentences Can Do the Job <ul><li>Mycobacterium tuberculosis has re-emerged as a major public-health threat. </li></ul><ul><li>Instead of being eradicated, drug-resistant strains have evolved and have been documented in every country surveyed. </li></ul><ul><li>Once a strain of M tuberculosis develops resistance to isoniazid and rifampicin, it is defined as multidrug-resistant tuberculosis (MDR-TB). </li></ul><ul><li>Mukherjee et al p.474 </li></ul>
  29. 29. Revision <ul><li>Writing is rewriting </li></ul><ul><li>Put the manuscript away for a day or more and come back to it fresh </li></ul><ul><li>When you reread it, read it out loud. </li></ul>
  30. 30. Revision: Organisation <ul><li>Review and revise the large elements </li></ul><ul><li>Do you have all the elements? </li></ul><ul><li>Are they all in the right order? </li></ul><ul><li>Consult your checklists </li></ul>
  31. 31. Revision: Paragraphs <ul><li>Does each major topic have its own paragraph? </li></ul><ul><li>Is there a clear topic sentence at the top of each paragraph? </li></ul><ul><li>Can a long paragraph be broken up into logical subtopics? </li></ul><ul><li>Is the sequence of the sentences within the paragraphs logical? </li></ul>
  32. 32. Topic Sentence: At the top <ul><li>Two reports in today’s Lancet advance knowledge of the transmission and distribution of prions, the infectious agent causing transmissible spongiform encephalopathies. </li></ul>
  33. 33. More… <ul><li>“ 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.” </li></ul>
  34. 34. And a bit more … <ul><li>“ Although not highly contagious, Creutzfeld-Jakob disease (CJD) has long been known to be transmissible.” </li></ul>
  35. 35. And so on … <ul><li>“ Variant CJD (vCJD) is probably caused by infection of human beings by …” </li></ul>
  36. 36. Revision: Sentences <ul><li>Read your prose out loud. </li></ul><ul><li>Can you finish each sentence on one breath? </li></ul><ul><li>Are your sentences simple and direct? </li></ul><ul><li>Look carefully at long sentences </li></ul><ul><li>Look at sentence length variety </li></ul>
  37. 37. Is it more than one sentence? <ul><li>“ 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.” </li></ul><ul><li>William Strunk, Jr </li></ul>
  38. 38. Spoon feed <ul><li>Do not flood your reader with information faster than he or she can absorb it. </li></ul>
  39. 39. Kill Your Babies <ul><li>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. </li></ul>
  40. 40. Good Prose <ul><li>“ Prose is bad when people stop to look at it.” </li></ul><ul><li>T E Lawrence </li></ul>
  41. 41. Who-do <ul><li>Keep subject and verb close together </li></ul><ul><ul><li>“ Critics of the placing of any extra barrier between regulatory approval and prescribing argue that it is rationing by stealth.” </li></ul></ul><ul><ul><li>Critics argue that placing additional barriers between regulatory approval and prescribing is rationing by stealth. </li></ul></ul>
  42. 42. Who-do <ul><li>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. </li></ul><ul><li>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”. </li></ul>
  43. 43. Nominalizations <ul><li>Nominalization: Making a verb into a noun </li></ul><ul><ul><li>We conducted an investigation … </li></ul></ul><ul><ul><li>We investigated … </li></ul></ul><ul><ul><li>We conducted a review of … </li></ul></ul><ul><ul><li>We reviewed … </li></ul></ul>
  44. 44. Use Signposts <ul><li>Signposts help keep your readers on track </li></ul><ul><ul><li>“ First … second … third …” </li></ul></ul><ul><ul><li>“ On the other hand…” </li></ul></ul><ul><ul><li>“ By contrast, …” </li></ul></ul><ul><ul><li>“ In some cases, however …” </li></ul></ul><ul><ul><li>“ Therefore…” </li></ul></ul><ul><ul><li>“ In summary,…” </li></ul></ul>
  45. 45. Keep related words together <ul><li>“ New York’s first commercial human-sperm bank opened Friday with semen samples from 18 men frozen in a stainless steel tank.” </li></ul><ul><li>“ 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.” </li></ul><ul><li>Strunk W </li></ul>
  46. 46. Related items together <ul><li>Keep positives together and negatives together </li></ul><ul><ul><li>“ Subjects with myocardial infarction were less likely to be married, older, drank less alcohol, were better educated, and were more likely to smoke. </li></ul></ul><ul><ul><li>“ 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.” </li></ul></ul><ul><li>Browner </li></ul>
  47. 47. Comparisons <ul><li>Keep comparisons together – Browner </li></ul><ul><ul><li>“ 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 ” </li></ul></ul><ul><ul><li>“ 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 . </li></ul></ul>
  48. 48. Respectively <ul><li>Respectively means: “You figure it out.” </li></ul><ul><ul><li>“ The rates in the four groups (young men and women, older men and women) were 10%, 13%, 8%, and 21%, respectively” </li></ul></ul><ul><ul><li>“ The rates were 10% in young men, 13% in young women, 8% in older men, and 21% in older women.” </li></ul></ul>
  49. 49. Needless Words <ul><li>A majority of most </li></ul><ul><li>a number of several </li></ul><ul><li>at this point in time now </li></ul><ul><li>despite the fact that although </li></ul><ul><li>has the capability of can </li></ul><ul><li>in order to to </li></ul><ul><li>with regard to about </li></ul>
  50. 50. Some Games to Play <ul><li>Write without using the verb to be. </li></ul><ul><li>Edit something you wrote – reducing your word length by half. Better? </li></ul><ul><li>When you read something that strikes you as well written, analyze it. Topic sentences? Signposts? Sentence structure? </li></ul>
  51. 51. “ Short, meaty, and clear” <ul><li>“ 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. </li></ul><ul><li>” Mimi Zeiger. </li></ul>
  52. 52. What editors look for <ul><li>Short, clear, precise title </li></ul><ul><li>Good abstract </li></ul><ul><li>Good design and methods </li></ul><ul><li>Clear conclusions </li></ul><ul><li>Brevity </li></ul><ul><li>Follow instructions </li></ul>
  53. 53. What reviewers look for <ul><li>Good design and methods </li></ul><ul><li>Simple tables and figures </li></ul><ul><li>Logical organisation </li></ul><ul><li>Brevity </li></ul><ul><li>Balance </li></ul><ul><li>Appropriate statistics </li></ul><ul><li>Their papers </li></ul>
  54. 54. What was written…what it means? <ul><li>It has long been known… </li></ul><ul><li>A definite trend is evident… </li></ul><ul><li>Of great theoretical importance… </li></ul><ul><li>While it has not been possible to provide definite answers… </li></ul><ul><li>Three groups were chosen for detailed study… </li></ul><ul><li>Typical results are shown… </li></ul><ul><li>It is believed that… </li></ul><ul><li>It is generally believed that… </li></ul><ul><li>A careful analysis of available data… </li></ul><ul><li>Thanks are due to John B for assistance with the experiments and to Jose G for valuable discussion </li></ul><ul><li>I didn’t look up the reference </li></ul><ul><li>There was no statistical significance </li></ul><ul><li>Interesting to me </li></ul><ul><li>An unsuccessful experiment, but I hope to get it published </li></ul><ul><li>The other results were less clear </li></ul><ul><li>The best result is </li></ul><ul><li>I think </li></ul><ul><li>My colleague thinks so too </li></ul><ul><li>I lost some data </li></ul><ul><li>John B did the work; Jose G explained what it meant </li></ul>
  55. 55. Useful Books <ul><li>Scientific Writing: Easy when you know how. Peat J et al. London. BMJ Books. 2002 </li></ul><ul><li>Writing and Publishing in Medicine, 3 rd Ed. Edward J Huth. Baltimore Maryland. Williams & Wilkins. 1999. </li></ul><ul><li>Publishing and Presenting Clinical Research. Warren S Browner. Baltimore Maryland. 1999. Williams & Wilkins. </li></ul><ul><li>Essentials of Writing Biomedical Research Papers. Mimi Zeiger. New York. McGraw-Hill. 2nd Edition, 2000. </li></ul>