⁶The NIPA accounts treat as ‘durable’ those goods whose expected lifetime is 3 years or more, but at the annual (or quarterly) frequency many more goods (and even services) are arguably durable – for example, Blinder, Deaton, Hall, and Hubbard (1985) mention clothes and shoes, and Hai, Krueger, and Postlewaite (2020) argue that many services are durable at the annual frequency, which explains why people take vacations once a year.