Figuring out Scotland's jobless queue
The Office for National Statistics says Scottish unemployment is down, Labour say it's up - so who is right?
The ONS does not provide monthly figures on overall unemployment.
Rather, the key measure of the jobless total is a rolling three month average.
The latest figures are an average for November, December and January; the figures released last month were an average for October, November and December, and so on.
Statisticians say this method tends to produce an accurate picture, which is seasonally-adjusted before publication.
By contrast, according to one ONS expert, monthly figures are "incredibly volatile ... they go up and down like a yo-yo".
And so the ONS says the most reliable way to tease out a trend is to compare the latest three month period with the previous non-overlapping three month period.
This month that means comparing the average for November, December and January with the average for August, September and October.
That is how the ONS arrives at a fall in Scottish unemployment of 16,000 over a three month period.
Labour, by contrast, have compared the latest three months (November, December, January) with the previous overlapping three months (October, November, December). In short they have taken out January and put in October.
The statisticians will tell you that this is less revealing.
Why? Well, two of the three months included in both sets of data are the same - and because the figures are averaged over three months you cannot tell which month is affecting the figures in which way.
In short, Labour's claim that "unemployment in Scotland has risen by 2,000 in the past month" is not an interpretation of the figures which the ONS would regard as sensible.
The following statements are true:
- The latest three month average for Scottish unemployment is 11,000 higher than it was in the same three month period one year ago.
- The three month average for November, December and January is 16,000 lower than it was in August, September and October.
- The three month average for November, December and January is 2,000 higher than it was in October, November and December.
- Using the statisticians' preferred method, there has been a fall in unemployment in Scotland every month for the past four months but the figure is still higher than it was a year ago.
The waters are likely to get even muddier as we approach the Scottish elections.