Nicola Sturgeon has stressed the 'stay at home' message remains in place in Scotland after Boris Johnson eased coronavirus lockdown measures.The First Minister said the "all-important" R number is still too high for lockdown to drastically change at the moment.She revealed Scotland's R number is estimated to be between 0.7 and 1, with the rate of transmission believed to be higher than in other parts of the UK.So what is the R number, how does it work and why is it higher in Scotland?The R number is at the heart of Ms Sturgeon's decision not to take Scotland out of lockdown.On Thursday, the First Minister extended lockdown for another three weeks due to the number "hovering around one" instead of below it.The R number is short for the