GDP is a bad gauge of material well-being. Time for a fresh appro would you du be: a le Val monarch sha or a modern office-worker? The cu s of servants. He vio king has ears, the finest silks and eats m the richest foods. But he is also a fle martyr to foothache. He is prone HCu to fatal infections. It takes him a g week by carriage to travel between palaces. And he is tired of p listening to the samejesters. Life as a 21st-century office drone fi looks more appealing once you think about modern dentistry, c antibiotics, air travel, smartphones and YouTube. The question is more than just a parlour game. It shows how tricky it is to compare living standards over time. Yet such comparisons are not just routinely made, but rely heavily on a single metric: gross domestic product (GDP). This one number has become shorthand for material well-being, even though it is a deeply flawed gauge of prosperity,and getting worse allthe time (see pages 21-2 That be levels of anxiety in the rich world about everything from stagnant in comes to disappointing productivity growth Faulty speedometer designed to do Defenders of GDP say that the statistic is not what is now asked of it. A creature ofthe os slump and the exigencies of in 940s, its original purpose wasto mea sure the economy's capacity to then GDP has become a lodestar for policies to set taxes, fix unemployment