Letter to Editor
re: Winter weather generates Scottish wind-power boost – http://goo.gl/xQE4TI
I write to you in a personal capacity as a retired statistician who is utterly fed up with the way statistics are used in debates about energy in Scotland to misinform and mislead.
WWF has started a new policy of putting out a monthly press release about how many households are having electricity supplied by wind. But, despite being told of their error, they continue to put out statistics based on an incorrect definition of a household.
Households can have two meters for a variety of reasons, most commonly for off-peak storage heaters. WWF’s figures, which the article quotes, are derived from a theoretical model which assumes average annual UK household electricity consumption to be 3,790 kWh. Official statistics for 2013 show a Great Britain household average of 4,065 kWh and a Scotland average of 4,435 kWh.
The model overstates the number of households supplied by 17%.
But it gets worse.
The model assumes equal electricity consumption in each month. In December, domestic consumption is over 20% higher than a notional average month.
The combined effect of these errors is to overstate the number of households theoretically supplied by wind-generated electricity in December by nearly 40%. The model assumes the average household uses around 320 kWh in December but the reality is over 440 kWh.
If WWF intends to make a serious contribution to the discussion of energy policy in Scotland, it could start by not providing misleading statistics. By presenting figures for households, which account for less than half of electricity consumption, and by understating per household consumption it presents a rosier picture that fits with its world view but isn’t real.
Dr. David Gordon
(full address supplied)