One of the perks of this blog is repetition. There are areas afield of the core focus (which itself moves) but there’s a lot of repetition. This is good. Jason Zweig once said that his Wall Street Journal articles were just the same principles in different forms.
There are other intervals. Sleep and exercise seem to be daily intervals. Eating might be longer or shorter. A business’s innovation interval depends on the industry. What’s the interval might be an interesting question.
There are vaccine intervals. Pfizer and Moderna tested three and four weeks and were (largely) administered in that time space too. But not always.
“In Quebec, in early 2021, the world was short on vaccines. To spread the doses in Quebec they decided to spread the interval to sixteen weeks. The researchers looked at the immune responses after the second doses and found a lot of similarities to people with hybrid immunity: high levels of antibodies, and neutralizing diverse coronavirus variants.” – Ewen Callaway, Nature podcast, October 2021
In Quebec at least the longer interval worked better.
Part of what makes cac such an interesting business angle is that there are a lot of ways to reduce the number and a low cac changes a lot of the economics. Intervals are like that too. The cost to experiment in intervals is low but the effect might be large.
DuoLingo experimented a lot with their reminders and what ultimately worked was one of their early interval tests, remind people about a day later. That will happen with experiments, but knowing about intervals as an option expands our field of experiments.