In a message dated 9/1/98 9:42:46 AM, hanson@econ.berkeley.edu wrote:
>Curt Adams writes:
>>>http://homenet.andrew.cmu.edu/progress/research.html
>>>
>>>I find it thoughtful, careful, and persuasive. Contrary
>>>to speculation on this list, the study gives clear
>>>indications of direction of causality. Furthermore,
>>>the study fits with my experience.
>>
>>I can't find any good indications of direction of causality. Indeed, the
>>path analysis in Figure 1 explicitly assumes that internet usage
>>affects followup psychological status and not the other way around.
>
>Huh? Isn't there an arrow from the the lower left social/psych box
>straight to the internet use box?
That's from the pre-trial psychological conditions. Changes in psychological state after the screening test don't affect internet use, by their model.
>Re-examining Table 3, I find reasons for caution. Their format is odd,
>relative to economics standards, as they don't include standard errors.
>And the coefficient values of soc/psych influence on internet use are
>about the same size as internet use influence on soc/psych. So I'd want
>them to verify that the scaling of the parameters implies that in fact
>the estimated influence one way is much bigger than the other way. Given
>that they do that, I'd be comfortable again with their results.
The study's nowhere near large enough to conclude that for depression. With loneliness, the difference should be significant because the association between usage and pre-study is negative, while the post study association is positive.
The details of the study were better than the summary implied. I'd like to see the results without the internet usage hours truncated. If there is a causal relationship, extremely heavy users should be very messed up. One hypothesis would be internet addiction, a la gambling/alcohol/etc addiction. In this case, light and moderate users should be fine and the heavy users will be the ones with the problems. Destructive addictive behaviors often have tangled causal relationships - depression make you drink, drinking makes you depressed, etc.
FWIW, I find the internet unsatisfying as a social medium. I speak much faster than I type and I much prefer the phone.