9 The diagram below shows some "Cycle to work" data taken from the 2001 and 2011 UK censuses. The diagram shows the percentages, by age group, of male and female workers in England and Wales, excluding London, who cycled to work in 2001 and 2011.
\includegraphics[max width=\textwidth, alt={}, center]{cac31da4-f1ad-4c34-a47f-2bc68c2304f1-10_899_1537_524_283}
The following questions refer to the workers represented by the graphs in the diagram.
- A researcher is going to take a sample of men and a sample of women and ask them whether or not they cycle to work.
Why would it be more important to stratify the sample of men?
A research project followed a randomly chosen large sample of the group of male workers who were aged 30-34 in 2001.
- Does the diagram suggest that the proportion of this group who cycled to work has increased or decreased from 2001 to 2011?
Justify your answer. - Write down one assumption that you have to make about these workers in order to draw this conclusion.