Whenever this issue comes up I feel the need to relay a story about a meeting with a databroker in 1998 who was tracking menstrual cycles using purchasing records of a wide variety of consumer goods. They will track you to optimize their manipulative, targeted advertising whether you have an invasive app or not.

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annzabelle 6 hours ago | parent | next [-]

I've heard rumors, maybe that far back, of women getting mail ads for baby clothes a couple weeks before having a positive pregnancy test.

	▲	vasco 6 hours ago \| parent [-]
		You are misremembering, what it you're referring to is the Target pregnancy prediction score which was advertised a lot in the early 2010s as the way "big data" was going to change the world because they figured pregnant women bought similar things https://www.forbes.com/sites/kashmirhill/2012/02/16/how-targ...

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m463 5 hours ago | parent | prev [-]

I wonder about not only baby or feminine supplies, but also snack coupons and dating apps

	▲	kevin_thibedeau 5 hours ago \| parent [-]
		Any behavioral pattern with a 28 day correlation will pop out. Once you get a rough estimate, you can aggregate subjects with dates shifted into alignment to find more subtle correlations.