But mass transit has many other effects besides the seatbelts. For example, cars leave whenever you want them to, while public transport leaves at fixed times. In a bus or train there will often be many strangers, while there will usually be none in a car. Places with good mass transit might be that way for other reasons, like population density, terrain, wealth, political climate, etc.
I doubt you will be able to get a meaningful result about the activity of children in relation to seatbeltiness while controlling for all of these factors.
Side issue: cars leave when the person driving is willing to leave, which isn’t the same thing as being the driver yourself or dealing with mass transit schedules.
I’ve heard for New York and would find it plausible for other places with good mass transit, that New Yorkers do more walking than people in places with little mass transit.
It might be possible to sort out at least some of the confounding factors—not every city has good mass transit, for example.
But mass transit has many other effects besides the seatbelts. For example, cars leave whenever you want them to, while public transport leaves at fixed times. In a bus or train there will often be many strangers, while there will usually be none in a car. Places with good mass transit might be that way for other reasons, like population density, terrain, wealth, political climate, etc.
I doubt you will be able to get a meaningful result about the activity of children in relation to seatbeltiness while controlling for all of these factors.
It would be complicated, and you might be right.
Side issue: cars leave when the person driving is willing to leave, which isn’t the same thing as being the driver yourself or dealing with mass transit schedules.
I’ve heard for New York and would find it plausible for other places with good mass transit, that New Yorkers do more walking than people in places with little mass transit.
It might be possible to sort out at least some of the confounding factors—not every city has good mass transit, for example.