Introduction

Data gathered from surveys, censuses or records are usually voluminous — so bulky, scattered and disorganised that they cannot be understood as they stand. Before such raw figures can be interpreted, compared or put to any further statistical treatment, they must first be arranged into a compact, orderly and presentable form. This is exactly what presentation of data achieves: it converts a large, unwieldy mass of collected numbers into something a reader can absorb readily and comprehend at a glance. Good presentation lets the data "speak" — it makes the facts hidden inside the numbers visible and meaningful.

There are broadly three forms in which data can be presented:

• Textual (or descriptive) presentation — the figures are described within the running text of a passage.
• Tabular presentation — the figures are set out systematically in rows and columns.
• Diagrammatic presentation — the figures are shown through diagrams, charts and graphs.

Textual presentation describes the data inside ordinary sentences. It is most suitable when the quantity of data is small. Its advantage is that the writer can weave the figures into an argument and emphasise particular points while narrating them. Its serious drawback, however, is that the reader has to go through the entire text to grasp the numbers, and comparison becomes tedious when many values are involved.

Tabular presentation arranges data in rows (read horizontally) and columns (read vertically). A table with three rows and three columns, for example, is a $3 \times 3$ table giving $3 \times 3 = 9$ items of information in nine boxes called cells, each cell relating one attribute to a number. The great strength of tabulation is that it organises data systematically for further statistical treatment and decision-making. The classification used in a table is of four kinds — qualitative (by attributes such as sex or location), quantitative (by measurable characteristics such as age or income, grouped into classes), temporal (by time — years, months, etc.), and spatial (by place — village, district, state, country).

Diagrammatic presentation is the third method and gives the quickest understanding of the situation compared with textual or tabular forms. It translates the highly abstract ideas contained in numbers into a concrete, easily comprehensible picture. Diagrams may be less accurate than tables, but they are far more effective for conveying and comparing the data at a glance.

Studying this chapter should enable you to present data using tables, to represent data using appropriate diagrams, and — importantly — to make an informed choice of the right form of presentation (textual, tabular or diagrammatic) and the right type of diagram for a given set of data, so that the presentation becomes meaningful, comprehensive and purposeful.