1. Statistical Editor, Health & Social Care in the Community
26 March 2008
Statistical presentation in international scientific publications 2. A symptomatic review
Malcolm Campbell
Lecturer in Statistics, School of Nursing, Midwifery & Social Work, The University of Manchester
Statistical Editor, Health & Social Care in the Community
Statistical presentation - 2. A symptomatic review

2. 2. A symptomatic review Contents
26 March 2008
2. A symptomatic review Contents
2.1 Statistical reporting
2.2 General (but not definitive) advice
2.3 The structure of a paper
2.4 Statistical errors in submitted papers
2.5 What should we do?
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

3. 2.1 Statistical reporting Presenting statistics in scientific papers
26 March 2008
2.1 Statistical reporting Presenting statistics in scientific papers
A scientific research paper should contain sufficient information to allow readers to
assess the authors’ aims, material, methods, findings and interpretation
decide whether their conclusions are justified
apply the authors’ conclusions to their own practice
repeat the study in their own setting, if required
Quantitative research papers show (or hide?) information statistically
numbers, estimates, statistics, test results, p-values…
but the reader still needs to be able to do 1 to 4
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

4. Statistical presentation - 2. A symptomatic review
26 March 2008
Statistical reporting in research papers Lies, damned lies and submissions to journals
Papers submitted to healthcare journals have a generally poor standard of statistical reporting
many papers do not have the right structure
occasionally the study design is at fault
most authors choose the correct methods to analyse their data but fall down on the description of the methods and the presentation of the results
others present sequences of p-values without explanation, inviting the reader to “guess the test”
many brush non-significant p-values out of the way
tables of findings are often inconsistent, too complicated or depend on the text for their explanation
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

5. Statistical presentation - 2. A symptomatic review
26 March 2008
2.2 General (but not definitive) advice Conventions, recommendations and suggestions
These presentations give general advice on how to present statistical findings in papers
there are common conventions, style and sense
some recommendations on good practice
There are few absolute rules
different journals (and editors) have different styles
always read the journal’s “Instructions to Authors”
it may be necessary to bend the rules occasionally
accept that research in healthcare may not be perfect!
Important bottom line: readability
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

6. The Good, the Bad and the Ugly Examples of good, bad and ugly practice
26 March 2008
The Good, the Bad and the Ugly Examples of good, bad and ugly practice
We will look at examples of all three in published papers
“The Good” are ideals
“The Bad” may be slightly wrong
but “The Ugly” should have been corrected before printing
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

7. Statistical presentation - 2. A symptomatic review
26 March 2008
2.3 The structure of a paper Quantitative papers are usually laid out as follows
Title: What was the study about, in a line?
Authors: Who “performed” the study?
Abstract: What was the study about, in a paragraph?
Introduction: Why was the study carried out?
Methods: How was the study carried out?
Results: What did the study find?
Discussion: What do the findings mean?
Acknowledgements: Who should be thanked?
References: What essential references were used?
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

8. Statistical presentation - 2. A symptomatic review
26 March 2008
IMRaD for healthcare papers The standard structure for research papers (ICJME, 2005)
Many (but not all) healthcare journals adopt this structure for main text of research papers
Introduction, Methods, Results and Discussion
these sections may be broken down into subsections
It reflects the process of scientific investigation
why the study was done, how it was done, what was found, what it means
though not always the order in which things were done!
use IMRaD even when planning for a journal that uses other sections to get overall structure right
should be easy to make minor changes to the structure before submission
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

9. Statistical presentation - 2. A symptomatic review
26 March 2008
Structures in selected journals Sections used by healthcare journals (* = structured Abstract)
BMJ
HSCC
Midwifery
J Adv. Nursing
J Clinical Nursing
Nurse Educ Today
Abstract*
Abstract
Introduction
Introduction/
Background
Lit review
Methods
The study
Results
Findings
Discussion
Conclusions
Acknowledg
Refs (Vanc)
Refs (Harv)
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

10. Statistical presentation - 2. A symptomatic review
26 March 2008
Common faults with authors’ structure How not to lay out a quantitative paper (eg Hall et al, 1998)
The Introduction should not include any findings or conclusions
The Methods should not include any findings
information not known before the data were collected should ideally be in the Results
The Results should not repeat detailed findings already summarised in tables
The Discussion should not introduce findings not already in the Results
The References should not be in the style of another journal (ie not the BMJ!)
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

11. Methods or Results? What goes where (eg ICJME, 2007)
26 March 2008
Methods or Results? What goes where (eg ICJME, 2007)
International Committee of Medical Journal Editors (2007) at :
“The Methods section should include only information that was available at the time the plan or protocol for the study was written; all information obtained during the conduct of the study belongs in the Results section. ”
I would expect the Results to start with
number of participants, participation rate, details of characteristics of the participants…
Sometimes better for readability to include some “results” in the Methods
Not all papers or journals follow this!
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

12. The Bad Lack of structure confusing
26 March 2008
The Bad Lack of structure confusing
Papanikolaou et al (2003)
Pressure ulcer risk assessment: application of logistic analysis, J Advanced Nursing 44(2),
title misleading – they meant logistic regression
does not follow IMRaD structure
characteristics of participants in Methods section
analysis of variables used for logistic regression with percentage breakdown per group also in Methods section
Results starts with the main analysis, logistic regression
[also no sample size calculation (only 25 patients with pressure ulcers v 473 without)
inconsistent percentages and p-values of “0.00”]
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

13. Statistical presentation - 2. A symptomatic review
26 March 2008
2.4 Statistical errors in submitted papers 100 consecutive non-RCT peer reviews+ (Altman, 1998)
Yes
Unclear No
Objective clear? 83 6 11
Appropriate study design? 72 25 3
Source of subjects? * 10
Sample size calculation? * 63
Satisfactory response rate? * 49 23 2
Methods described adequately? 47 53
Statistical analyses appropriate? 41 37 22
Statistical presentation satisfactory? 14 86
Confidence intervals given? 51
(CIs given inappropriately)
(+8)
Conclusions justified? 40
Paper statistically acceptable? 4 96
If not, could it become acceptable? 89 1
* not always applicable
+ for BMJ
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

14. Statistical presentation - 2. A symptomatic review
2.5 What should we do? Never fear - help is at hand! – Three sources of advice
ICMJE uniform requirements for manuscripts
International Committee of Medical Journal Editors (2007) at
eg use double spacing, pages should be numbered, start each section/table/figure on a new page
Journal’s instructions to authors
please read them!
Published reporting guidelines for different study designs
eg CONSORT, STARD, TREND, STROBE…
26 March 2008
Statistical presentation - 2. A symptomatic review

15. Guidelines for statistical reporting Standardised reporting guidelines
There are published guidelines for reporting certain types of study designs
cover the type of information to be reported and in what order/sections of the paper
but not the finer details of numerical reporting
refer to journals’ guidelines to authors
and more later!
Go to the EQUATOR Network for more details
a new initiative, Enhancing the QUAlity and Transparency Of health Research Network
26 March 2008
Statistical presentation - 2. A symptomatic review

16. Statistical presentation - 2. A symptomatic review
26 March 2008
The CONSORT statement (2001) Checklist/flow diagram for reporting randomised trials
CONsolidated Standards Of Reporting Trials
for reporting (parallel) randomised controlled trials
the statement – eg Moher et al (2001)
explanation and elaboration – eg Altman et al (2001)
download both documents and templates of checklist and flow diagram
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

17. Statistical presentation - 2. A symptomatic review
26 March 2008
The STARD statement (2003) Guidelines for studies of diagnostic accuracy
STAndards for Reporting of Diagnostic Accuracy
for studies comparing outcomes from new diagnostic test against reference standard
the statement – Bossuyt et al (2003a)
CONSORT adapted for studies of diagnostic accuracy
explanation and elaboration – Bossuyt et al (2003b)
download both documents and templates of checklist and flow diagram
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

18. Statistical presentation - 2. A symptomatic review
26 March 2008
The TREND statement (2004) Checklist for reporting non-randomised trials
Transparent Reporting of Evaluations with Non-randomized Designs
for reporting comparative trials without randomisation
the statement – Des Jarlais et al (2004)
CONSORT + theoretical basis of intervention, tests of baseline equivalence and corresponding adjustments of main analyses
download the statement
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

19. Statistical presentation - 2. A symptomatic review
26 March 2008
The STROBE statement (2007) Checklist/flow diagram for reporting observational studies
STrengthening the Reporting of OBservational studies in Epidemiology
reporting of cohort studies, case-control studies and cross-sectional studies (surveys)
the statement – eg von Elm et al (2007)
CONSORT + sources of potential bias + outcomes related to type of design + potential confounders and corresponding adjustments of main analyses
explanation and elaboration – eg Vandenbroucke et al (2007)
download both documents and templates of checklist and flow diagram
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review

20. Other guidelines For other kinds of studies
26 March 2008
Other guidelines For other kinds of studies
Extensions to CONSORT for other kinds of randomised trials
cluster RCTs – Campbell et al (2004) [no relation!]
non-inferiority/equivalence trials – Piaggio et al (2006)
herbal medicinal interventions – Gagnier et al (2006)
(coming) non-pharmaceutical interventions
download all documents
26 March 2008
Statistical presentation - 2. A symptomatic review
Statistical presentation - 2. A symptomatic review