The OCR large data set gives age-structure counts for the same 348 Local Authorities in 2001 and 2011. A student wants to investigate whether Local Authorities in Wales had an older age structure in 2011 than in 2001.
In this question you must show detailed reasoning.
State the population and the sampling units.
Describe the variables or summaries that should be compared.
Describe a suitable sampling method and explain one feature needed to make it valid.
State two limitations of the available data.