The phrase "activity by which" is correct and usable in written English.
It can be used to describe a specific action or process that leads to a particular outcome or result.
Example: "The activity by which we measure success is based on customer satisfaction and retention rates."
Alternatives: "process through which" or "method by which".
Soon enough, dating became an activity by which women tried to transcend class.
This led to an intense flurry of activity, by which I mean four people asked me about it.
Backscatter is a remote sensing activity by which electromagnetic energy is reflected back towards its source by terrain or particles.
Like listening to NPR's Morning Edition, the preparation and eating of breakfast belongs to that class of ritual activity by which we turn our sleeping soft selves into our outer selves.
Cause related marketing is a commercial activity by which businesses and charities or causes form a partnership with each other to market an image, product or service for mutual benefit.
Husserl and Meinong contended that the basic categories of objects mirror the various kinds of mental activity by which they are grasped.
Volitions have been defined as "special mental events or activities by which an agent consciously and actively exercises his agency to voluntarily direct his thoughts and actions" [ 9].
Multiple activities by which citizens earn their bread may, with equal propriety, be denominated an exercise of religion as may preaching or selling religious tracts.
If you think about it, Prep-Do-Review is the fundamental cycle of activities by which effective bosses manage — through a perpetual loop of prep-do-review-prep-do-review.
That's why we do things like regulate who drives cars, put warning signs for pregnant women on wine, demand licenses on dogs, check people for box cutters before they board airplanes — all common-sense activities by which we attempt to regulate the risks of our pleasures.
Emerging data suggest that Tanshinone IIA possesses significant anti-inflammatory activities, by which it ameliorates injury in various organ systems, such as the brain, lung and heart23,24,25,26,27,28,29. Notably, two randomized clinical trials are being undertaken to validate its effect on ischemic heart disease30,31.
