Working with evidence, Year 9

That he was being called on personally

提示Wherever you stand, the finger seems to follow you.

为什么Naming the technique is the first step with any piece of propaganda. Here it is direct address: the eyes, the finger and the word 'YOU' turn a general appeal into a private demand. The need for such posters is evidence too: until 1916 Britain's army relied on volunteers.

Guilt (or shame)

提示Picture his face, years later, if he has no answer for her.

为什么The poster says nothing about the enemy or the cause. It works on a man's fear of being judged by his own children. Naming the emotion a source plays on tells you how its makers thought their audience could be moved.

The country running short of food

提示Ask what German submarines were doing to the grain ships.

为什么Nobody prints a poster about a problem that does not exist. Read this way, propaganda is a window into its makers' fears: the campaign shows that U-boat sinkings were biting, months before rationing was brought in.

The audience each was written for

提示The same writer says different things depending on who is reading.

为什么Propaganda for people at home usually tries to keep spirits up; propaganda for the enemy tries to make them give up. The same event can be described in opposite ways in each. Audience is part of provenance, along with who made a source, when and why.

Censorship

提示It is the cutting-out that goes hand in hand with propaganda's putting-in.

为什么Propaganda adds a message; this removes whatever might contradict it. A historian reading wartime newspapers therefore asks what was left out, and looks for sources never meant for publication.

Casualties include the wounded and missing, not only the dead

提示Look up exactly what the heading of the column counts.

为什么The first question to ask of any number is what, precisely, was counted. A casualty is any soldier put out of action, and most of them survived. Misreading the label can make a careful figure say something its compilers never claimed.

4

提示Divide the later figure by the earlier one.

为什么'It grew by 60,000' and 'it quadrupled' are both true, but the second lets you compare this town with others of any size. Turning raw figures into a rate or a multiple is often what makes a table usable as evidence.

A few high salaries can pull the average up

提示Imagine nine people paid £1 and one paid £91, then work out the mean.

为什么An average hides the spread. If the managers' pay doubled while the weavers' pay stood still, the mean would rise and nearly everyone in the mill would be no better off. A true statistic can still give a false impression, so ask who is included.

Whether something else could explain the fall

提示Two events happening together is not proof that one produced the other.

为什么Cleaner drinking water, better housing or simply the end of an epidemic could each produce the same line on the graph. A supportable conclusion says only what the figures can bear: 'deaths fell after the sewers opened' is safe; 'because of' needs more evidence.

inflation

提示The same word describes pumping air into a tyre.

为什么A loaf cost far fewer pennies in 1850 than today, but wages were far lower too, so a price means little without knowing what people earned. Historians often ask how many hours an ordinary labourer had to work to buy a loaf, which lets them compare one century with another without being fooled by the changing value of money.