Scientific Writing

1. Scientific Writing MEST 201 Pr.Dr.RamezBedwani

2. Outcomes: • By the end of this lecture, the student will be able to Know definition, uses and types of statistics.

3. Material And Methods Patients And Methods

4. Material and Methods, Why? • Details that can help any researcher to follow the same steps. • Assure generalizability. • Assure avoidance of different types of bias.

5. Materials And MethodsGeneral Advice Title page Abstract Introduction Materials & Method Results Discussion Summary References Tables Figures Legends to Figures • New methods are described in details. • Previously published methods: Common:Enumeration+ref. - Uncommon: Short summary + ref.

6. Which tense to use in the Methods section • Use past tense throughout: • “We recruited 143 patients with moderate persistent asthma ….”

7. Material and Methods, What? 1. Research Design. 2. Setting. 3. Selection of Study Population. 4. Sample size calculation. 5. Data collection and Operational definition of variables. 6. Procedures. 7. Materials. 8. Statistical methods. 9. Ethics.

8. Material and Methods, What? 1-Research Design Research Design: plan chosen to answer the research Q.

9. Research Objective VS Research Design Estimation ------ Cross Sectional Study Association ----Case Control Study Cause Effect Relation -- Cohort Study Evaluation of Intervention- Clinical Trial

10. Research Design StatementExample Research Design : Cross sectional study Case Control Study Cohort Study Double Blind Randomized Clinical Trial

11. Material and Methods, What? 2- Setting Setting e.g. Out patient, Hospitalized patients, Cases in ICU Health units in rural areas, ……..

12. Setting Statement Example Study Setting: The study was conducted in a semi rural area located about 25 miles from the city Karachi, Pakistan” “ Maternal Charctersitics in relation to income in ………..” Eastern Mediterranean Health Journal, 13, 6, 2007

13. Material and Methods, What? 3-Study population • Sampling method • Inclusion and exclusion criteria • Method of allocation of groups

14. Population and Sampling • Population: what was the source of the population studied? • Dates of Data Collection: give the period over which data were collected.

15. Population and Sampling • Selection: How were individuals selected into the study? Inclusion criteria Exclusion criteria

16. Clinical and pharmacological variables as a risk factor fornifedipine-induced gingival overgrowth Eighteen patients taking nifedipine in regular doses for at least six months ( EXPOURE) participated in the study between 2003–2005. Prior approval was received from the Ethics Committee. Patients enrolled in this study were obtained from outpatients attending the Cardiology Department at the Faculty of Medicine,Hacettepe University ( SETTING). Australian Dental Journal 2007;52:(4):295-299

17. Clinical and pharmacological variables as a risk factor fornifedipine-induced gingival overgrowth Only patients who possessed at least 12 anterior teeth in both upper and lower arches participated in the study. Mean daily nifedipine dose was 30 mg in all patients. Exclusion criteria were: smoking, periodontal treatment undertaken less than six months prior to the baseline visit, concomitant systemic disorders known to affect the periodontal tissues, and use of phenytoin and cyclosporine. Patients with periodontitis (both treated and untreated) were also excluded from the study Australian Dental Journal 2007;52:(4):295-299

18. Material and Methods, What? 4.Sample size calculation. Sample Size is critical to precision of the estimate and power of the study.

19. Factors Affection Sample Size Calculation Confidence level (1- ) Power (1- ) SD Sample Accuracy

20. Sample Size StatementExample • Sample size required is 30 to achieve 80% power at 5% level of significance, provided that prevalence of the outcome is …% and maximum error in estimate equal to … %. • Reference: • The sample size was calculated using NCSS 2004 and PASS 2000 Program.

21. Sample Size StatementExample ….. to detect a mean difference of at least 10 mm Hg The minimum sample size required in each group is 52to achieve a study power of 80% and level of confidence 95%. • References: The sample size was calculated using Medcalc Program version 8.1NCSS 2004 and PASS 2000 Program.

22. 5. Data collection and Operational definition of variables Operational definition of outcome variables and independent variables.

23. Main variables • Outcome variables: • Dependent variables • In observational studies: what you are trying to predict • In Clinical trials: endpoints: Primary Secondary

24. Main variables Exposure Variables Main exposures of interest Confounders/Effect modifiers

25. Main Variables Operational definition of variables Transformation of variables Creation of categorical variables Why? Number of levels? Predefined levels or quantiles?

26. Measurements Who made the measurements? What qualification did they have for the job? What training was undertaken? Were they and/or the patients masked (blinded)?

27. Measurements • Conditions of measurement • Sitting, standing,… after 10 minutes rest, … • Instrumentation • Including model, source and supplier of instruments • Precision of measurements • Source of consumables

28. Data Collection and definition of Variables e.g. BMJ. 2006 March 4; 332(7540): 521–525. • Chronic stress at work and the metabolic syndrome: prospective study Data on the components of the metabolic syndrome were collected during the clinical examination, using the definition of the National Cholesterol Education Program by the presence of three or more risk factors( Ref). We used obesity (defined as body mass index > 30) as an indicator of risk for the syndrome.

29. Data Collection and definition of Variables e.g. BMJ. 2006 March 4; 332(7540): 521–525. Chronic stress at work and the metabolic syndrome: prospective study Data collection and definition of Variables : Data on the components of the metabolic syndrome were collected during the clinical examination, using the definition of the National Cholesterol Education Program by the presence of three or more risk factors( Ref). We used obesity (defined as body mass index > 30) as an indicator of risk for the syndrome.

30. Clinical and pharmacological variables as a risk factor fornifedipine-induced gingival overgrowth definition of Variables Gingival overgrowth was assessed in both vertical and horizontal dimensions at each papilla on the buccal and lingual aspects. A total of 20 dental papilla (10 maxillary papilla and 10 mandibular papilla) were evaluated in each patient in the anterior region. The height of the gingival tissue was measured from the cemento-enamel junction (CEJ) to the free gingival margin according to Miller and Damm’s index (0, 1, 2, 3 scores).16 Australian Dental Journal 2007;52:(4):295-299

31. 5. Data collection and Operational definition of variables: Measurement . Measurement (validity, reliability, precision)

32. 5. Data collection and Operational definition of variables • 8. Material e.g. Identify precisely all drugs and chemicals used including: generic names, doses and routes of administration.

33. 6. Procedures • Describe: • Surgical technique. • - Radiological technique. • -

34. Material • If drug (preparation, dose, timing…etc).

35. 8- Statistical methods. • Describe in details

36. Assumptions for Statistical Analyses Independence, normal distribution, multiple measurements, …….

37. Statistical analysis Mann Whitney U-test test was used to compare data in responders and non-responders. For correlations between GCF–plasma drug concentrations, clinical parameters and demographic parameters, Spearman’s correlation rank was used. Fischer’s exact test was also used to determine the difference between males and females.

38. Statistical methods StatementExample Statistical Analysis We used logistic regression analysis to assess the odds ratios of the metabolic syndrome for the different explanatory variables • BMJ. 2006 March 4; 332(7540): 521–525. • Chronic stress at work and the metabolic syndrome: prospective study

39. A few words about math… Equations are often necessary to describe in the methods Peripheral equations should be avoided or moved to an Appendix – Define all terms in your equations.

40. Statistical Analysis • What comparisons were made? • In trials was the comparison by “intention to treat” or “per protocol”? • Using what technique? • What software was used and (where relevant) which programs? • (What p-values were taken to be significant)

41. Statistical Analysis • Justify any sub-group analyses: • Were they in the original protocol? • Why were they done? • Were they post-hoc, because you didn’t find what you originally expected?

42. 9- Ethics Title page Abstract Introduction Materials & Method Results Discussion Summary References Tables Figures Legends to Figures Ethical permission must be acknowledged in the methods section.

43. Evaluation of the Materials and Methods Title page Abstract Introduction Materials & Method Results Discussion Summary References Tables Figures Legends to Figures The reviewer asks the following questions : 1- Is the study population detailed adequately ? 2- Are the methods described well enough to reproduce the experiment ? 3- Is the study design clear ? 4- Are statistical methods included ?

44. Assignment