In a message dated 9/1/98 11:49:42 AM, hanson@econ.berkeley.edu wrote:
>They are trying to use the timing of variables to infer causality;
>things that are measured earlier likely cause, and are not caused by,
>things that are measured later. So to disambiguate cause, they measure
>soc/psych both before and after internet use. Of course there's always
>the possiblity of unmeasured variables causing everything, such as
>unmeasured "during" soc/psych. But it seems to me they have done the
>reasonable thing with the data the have.
Even by that standard, then, they've overreached in deducing causation. Neither the family communication-usage nor depression-usage correlations changed significantly from pre to post, although loneliness probably did.
>Huh? They used log of internet hours, without truncation.
Oops, my bad.