Coding data Trudy Bekkering SR course 27 May 20151

What data should you collect? SR course 27 May comprehensive information about each study population and setting interventions and integrity of delivery Extract factors and variations that may have impact on results of study Extract information to decide whether results can be applied in their context. methods and potential sources of bias outcomes, results, authors’ conclusions citation, author contact details sources of funding, etc.

What data should you collect? SR course 27 May comprehensive information about each study population and setting interventions and integrity of delivery methods and potential sources of bias outcomes, results, authors’ conclusions citation, author contact details sources of funding, etc. information required for: references description of included studies risk of bias assessment analyses

SR course 27 May

Collecting outcome data SR course 27 May focus on those outcomes specified in your protocol be open to unexpected findings, e.g. adverse effects measures used definition (e.g. diagnostic criteria, threshold) timing unit of measurement for scales – upper and lower limits, direction of benefit, modifications, validation, minimally important difference numerical results may be in many formats - conversion may be required collect whatever is available no. participants for each outcome & time point

Data in many formats SR course 27 May OutcomeReported asTrials Volume transfused (mls)Mean and SEM Mean and SD Mean and something in brackets Median and something in brackets Two unlabelled numbers e.g. x(y) Bar chart showing mean per person per day Units transfusedMean and SEM Mean only Total in each group Volume adjusted for patient mass (mls/kg) Mean and SD1 Patients who had a transfusionNumber of patients3 Not measuredNot reported1

Data collection forms SR course 27 May organise all the information you need reminds you what to collect records what was not reported in the study records the decisions you make about each study source document for data entry into your review must be tailored to your review adapt from a good example paper or electronic – your choice

Hints and tips SR course 27 May plan what you need to collect – not too much or too little consider including: name of author completing the form Study ID (and Record ID if multiple reports of a study) plenty of space for notes (at beginning and throughout) source of each piece of information (e.g. page no.) tick boxes or coded options to save time ‘not reported’ and ‘unclear’ options format to match RevMan data entry provide instructions for all authors

What SR course 27 May Paper coding form

Excel coding form SR course 27 May

Minimising bias in data collection SR course 27 May two authors should independently collect data reduces error ensures agreement on subjective judgments and interpretations resolving disagreements can usually be resolved by discussion if not, refer to a third author pilot data collection process include each person assisting ensure criteria are consistently applied may need to revise form or instructions

Managing data SR course 27 May can enter data directly from form to RevMan may need to consider intermediate steps e.g. Excel spreadsheet group studies by comparison & outcomes measured calculations to convert into required statistics

Data needed for meta-analyses SR course 27 May Dichotomous data PainNo pain Intervention2080 Control4060

Data needed for meta-analyses SR course 27 May Continuous data NMeanSD Intervention Control

Available data for review SR course 27 May

Take home message SR course 27 May think carefully about the data you wish you collect design and pilot a data collection form should be done independently by two authors to minimise error and bias

References SR course 27 May Higgins JPT, Deeks JJ (editors). Chapter 7: Selecting studies and collecting data. In: Higgins JPT, Green S (editors), Cochrane Handbook for Systematic Reviews of Interventions Version (updated September 2008). The Cochrane Collaboration, Available from handbook.orgwww.cochrane- handbook.org Acknowledgements Compiled by Miranda Cumpston Based on materials by the Australasian Cochrane Centre Approved by the Cochrane Methods Board