since the 1980's, the obesity rate increased in the united states. during the same time period, computer usage also increased. are these two trends an example of causation, correlation, or both?
A lot of factors could have gone into this. The world has become a lot more accepting of the Obese from the 1980-Now. Right now, being "Fat" is ok in some situations.
There really is no difference between typing something and physically writing something, its the same amount of excersise for both.
The Obesity rate could have been triggered by a lot of things, but my best guess was the rise of conviency and efficiency. There is less work that needs to be put into tasks. Whether thats a good thing or a bad thing is completely up to you. You would have to survey those with Obesity to be able to determine whether those who have obesity are that way due to computer use.