A simple reason for skepticism about the iPhones/fertility link

Here is the background to the debate.  Here is more from Noah.  Here is a thread from researcher Caitlin Myers.  And here is some basic information:

In 2008, 1.9% is the share of the mobile-subscribing population with an iPhone wireless subscription.  As a percent of all adults that is 1.6%.

In 2009, it is 4.3%.  3.6% of all adults.

In 2010, 6.8%.  5.5% of all adults.

Plus conception to birth takes nine months (give or take!), noting that actual family planning may make this lag far longer.  In 2008 fertility rates already were falling pretty sharply.  The whole “maybe the iPhone messes up your dating processes” factor also requires some time to operate, especially since iPhones as a network of many many users, and whatever negative effects on socializing you think that might have, was still to lie in the future.  And what you could access on the iPhone then was far more limited than today.

So when the authors talk about diffusion explaining 33–52% of the decline in the general fertility rate among American women 15–44, I still do not get how that is supposed to operate.

The explanations I am hearing seem to be parasitic on world intuitions from 2026, not the time period under consideration.