Best way to represent data What is the best way to represent the following data graphically? Can I use a histogram
Year    Output per Person       Capital Employed
2010    16.3 units/annum        £40,000 p.p
2011    15.1 units/annum        £38,000 p.p
2012    14.4 units /annum       £35,000 p.p
2013    11.7 units per annum    £33,000 p.p
2014    10.8 units per annum    £30,000 p.p

 A: I see two main alternatives, the scatterplot (see Stephan's post, or a slightly different version below which is sometimes worth trying with time series), and superimposed time series (see the second plot below), though there are a number of other possibilities. 
However, beware of interpreting the appearance of correlation as meaningful. Specifically, since both your quantities are both "per person, per annum", you have a classical situation where you expect spurious correlation in the original sense of the term.


A: Probably best to do a simple scatterplot. Using R:
foo <- data.frame(year=2010:2014,output=c(16.3,15.1,14.4,11.7,10.8),
  capital=c(40,38,35,33,30)*1000)
with(foo,plot(capital,output,xlab="Capital Employed",ylab="Output per Person",pch=19))


Or also plot the years:
with(foo,plot(capital,output,xlab="Capital Employed",ylab="Output per Person",pch=NA))
with(foo,text(capital,output,year))


However, note that both capital and output decline over time. So either output is driven by capital... or both are independently driven by some time-dependent trend (or something in between). Be careful when interpreting correlations, especially over time.
