Selecting information to display

Most organisations have access to large amounts of information about any topic.

Any report must be very selective about the information that is displayed. It should concisely summarise the important features of the data. The decision about what is the important information in data is subjective but is critically important.

The report should summarise the most important features of the data.

Signal and noise

The distinction between the 'important' information in data and the rest is similar to the distinction between signal and noise in electronics and telecommunications. Engineers distinguish between the signal that is being communicated between two locations and the noise that is added by the communications channel. The noise degrades the signal and, in the worst cases, can make the signal difficult to detect.

Signal   =   information you want
Noise   =   'random' modification to the signal

As in electronics, an important goal of data presentation is to extract the 'signal' from a data set and clearly display it without the 'noise' of the less important detail in the data.

Example of signal and noise

The word 'CAST' can be seen below. This is the signal in the picture.

Drag the slider to the right to add random noise to the picture. Even when the slider is in the middle, it is becoming hard to distinguish the signal in the picture.

Adding noise makes it harder to detect the signal in the picture.


Prune out unnecessary detail

Many reports are filled with bar charts, pie charts, histograms, scatterplots and a variety of other plots, just because the researcher produced them when exploring the data! It is sometimes useful to ask yourself 'What single display of the data conveys the information most relevant to the message I wish to convey?' If there is more than one thing to convey, then more charts may be needed, but at least this priority approach prevents you from spending too much time on less important details, and at the same time encourages you to decide what really is important. Graphics, tables and text should only be included if they add new and interesting information about the data.

Before producing a report or other publication, it is important to first identify the most important information that you want to convey.