Bringing the nation to its Census

I’m not for one minute claiming to be the second coming of Derren Brown, but if you’re reading this in the UK I’m willing to bet there’s a fair chance you – like myself and millions of others – were completing your census form yesterday. As a collective body of data it provides the richest possible insight into how the UK has changed over time, and also facilitates planning for the country’s future.

What’s the difference between a census and a sample?

A census is a procedure in which data about an entire population is acquired and recorded. It is different to the more typical type of market research you may have participated in before (e.g. polls for government elections, consumer surveys) in that it is intended to survey everyone in the country and not just a representative sample – typically as small as 1,000 people – which inherently contains a margin of error.

The completion rate for the UK census (it is mandatory by law) was 94% in 2001, which means that statistical analysis can produce a much more accurate view of the nation than a mere sample. (For instance, a survey of 1,000 people would include only one respondent for every 60,000 people in the UK.) It also allows analysts to drill down to a greater level of detail than a basic sample would. A survey of a thousand UK residents would provide some insight into the UK as a whole but not about, say, dentists in Berkshire. A census does.

In short, the census is an important survey of the nation which a normal research sample can never hope to replicate. In effect, it is to people what a dictionary is to words – a reflection of the state of the entire population, not a subset of it. So even though it is a massively complicated and expensive exercise which is conducted only once a decade, it is a hugely valuable resource. (Imagine how little use a dictionary which only contained every thousandth word selected at random would be!)

The history of the census

The first census is thought to have been conducted by the Babylonians as early as 4000BC, giving them an essential guide as to how much food they needed to find. Records were held on clay tiles (the British Museum has an example of this). A millennium later, the Egyptians used censuses to work out how much of a labour force they needed to build the pyramids, and for planning the division of land. The Romans conducted censuses every five years, calling upon every man and his family to return to his birthplace to be counted.

In England the first census was the Domesday Book of 1086, commissioned by William the Conqueror to survey land and assets, primarily for the purpose of determining taxation. The results took a year to hand-write on sheepskin parchment in two huge books. However, a regular national process was not started in the UK until after the passing of the 1800 Census Act, driven by concerns that Britain would soon have more people than it was able to feed. Britain’s first official census was launched on 10th March 1801. Since then, the census has been conducted every ten years (except for 1941, during World War II).

What’s different this year?

The 2011 census includes questions relevant to civil partnerships for the first time, reflecting recent changes in legislation recognising these. Other new questions involve asking migrants their date of arrival in the country and the length of their intended stay. Respondents are also being asked to disclose which passports they hold.

The introduction of new questions has stirred some controversy in the past. When in 2001 a question asking about respondents’ religion was introduced, a global movement led to 0.7% of people in England and Wales – and a whopping 2.6% in the town of Brighton – declaring themselves as ‘Jedi’, making it the fourth largest religion in the country.

The census and you (and I)

Census data provides an invaluable resource for historians to track societal changes. Decade by decade, the UK has changed due to war, industry, disease, migration and a myriad of other factors. So although the census has always contained a core of questions counting population and households, other questions change from census to census, reflecting our constantly transforming nation. So for instance the 1911 census included questions on marriage and fertility at a time when the birth rate had been declining for over 30 years. The 1921 edition focussed on commuter flows to understand the implications of people moving out to the suburbs. And the 1971 census looked into migration patterns, in an era in which immigration from Commonwealth countries doubled.

A lot can change in ten years. It certainly has in my own life since the last census in 2001. Heather and I have moved house twice, we have both changed jobs twice, and we now have two children. The census aggregates and reflects all those micro-changes on a macro scale.

Census data also carries a forward-looking significance. Local and county councils use it to make forecasts to plan local amenities such as schools, medical and fire services. Retailers determine new store locations. Utility companies make infrastructure plans for water pipes and fibre-optic communication networks. The data which you and I provide by ticking boxes in a booklet is used in more ways than one can imagine, and impacts us in ways which are barely visible but nonetheless significant.

An invasion of privacy?

One of the things which has definitely changed in our world over the past decade has been an increased public awareness of privacy issues around personal data, and it will be interesting to see if this leads to a reduction in the completion rate. Advances in electronic data analysis make it much easier to glean individual data from members of very small geographical or other demographic populations. And, of course, an increase in targeted theft – we have all read the stories about laptops or CDs being stolen/lost on trains, haven’t we? – renders personal data in electronic form more vulnerable than ever.

But the reality is the personal data we provide on our census forms is neither particularly revealing nor sensitive. Anyone reading my submission would know that I am of Chinese descent, married with two kids, have access to two cars, live in a detached house and work 31-48 hours a week. My postman knows that. (Oh, and I’m Catholic. But that has never stopped the Jehovah’s Witnesses from coming round.)

And, as amateur genealogists will know, a person’s actual submissions do not become available for public access for 100 years. I’m not going to be around to worry about that.

There is nothing in my census form to tell you about my household income (which my credit card provider knows), what brand of breakfast cereal I prefer (Tesco Clubcard), my employment history (LinkedIn), my favourite music, films and TV programmes (Facebook) and my secret double identity at weekends where I wear dresses and high heels and answer to the name Agnes (er …)

My point is simply that, although the UK census requires us to provide personal information, there is little about it which is actually sensitive. And many of us regularly volunteer far more private information about ourselves in many other ways without batting an eyelid. Ever talked about your recent promotion or your new car down the pub? There you go.

It’s easy to get worked up into an uninformed panic about a Big Brother society and refuse to fill in the form. In theory non-completion carries a £1,000 fine, although whether this would actually be enforced is unlikely. Over a million people did not complete the 2001 census, but only 38 were prosecuted.

But why would you refuse to do so? Accurate data which supports public and private sector planning can only be a good thing, and having complained all weekend about having to waste an evening filling it in, it took me 20 minutes to do it on behalf of my family of four last night. Given its wider benefits, it’s not really that big a burden, is it? And, in a small way, I have contributed to a comprehensive and accurate record of the UK’s social graph. Call me a geek, but I think that’s rather cool.

Link: UK census website