# Lecture Two USING EXISTING DATA. Summarising numbers, presenting results.

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Lecture Two USING EXISTING DATA. Summarising numbers, presenting results

Summarising and presenting data in number In presenting data your own personality and the particular nuances of your data should also come through.

Presenting data in numbers In Plain Figures the authors give two reasons for presenting data: 1. So we and others can draw on the data for future reference 2. To demonstrate a point or support an argument

Reference Data 'reference data' more or less the raw data As they are collected and stored. Little has been done to them. Appear simply as collected. Lots of detail. Difficult to use. Too much information.

How to Use a Reference Table Never use a reference table as it is you can't just reproduce it into text you must derive a new table, showing what you want to show in the way you want to show it. You must always give a full reference back to the source (including table number).

Demonstration tables Can use either tables or charts for demonstration. Which you chose depends very much on what you want to say … but you must always use words as well. Numbers never speak for themselves.

Numbers never speak for themselves Tables - for conveying numerical values Charts - for conveying relationships Words - for conveying information

If you are producing a report from the data. 'The summary should be a clear concise statement of how the data contribute to the subject of the report, consisting of no more than three or four separate points each clearly supported by the accompanying table or chart' and 'the final choice of whether to use a chart or a table is made after writing the verbal summary' (Chapman, 1986, Plain Figures, p17) Always use words and if the summary mentions specific numbers: use a table if the summary is pointing to broad comparisons: consider a chart, for example a bar chart, a pie chart or a histogram in which you can see a clear visual comparison between variables.

Which numbers? absolute numbers - size indices - trends over time rates per number at risk - relative risk percentages - composition

Table 1.1 Abortions by marital status, England and Wales, 1971 to 1997

Table 1.2 Abortions by marital status, England and Wales, 1971 to 1997

Table 1.3 Abortions by marital status, England and Wales, 1971 to 1997

Table 1.4 Abortions by marital status, England and Wales, 1971 to 1997

Guidelines for Using Tables Round numbers Compare in columns and not rows Order rows and columns Give row/column totals or averages Use clear and consistent layout Give full details of sources Do not include too much Clear summary in text

When to use charts For communicating non-specific comparisons To make report/presentation more attractive To appeal to a wider audience To show trends over time

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