carnap wrote: ↑Wed Mar 14, 2018 10:32 am
This would be like suggesting that in a drug study you don't need a placebo group because you can just test people before they take the drug. But that doesn't work, you need to compare how the disease or condition progresses with and without the drug.
There's a good argument to be made that drug studies should not use placebo groups if enough other studies have been done with placebo groups and the progression of the disease is well known. But this is mostly because it's unethical to leave people without treatment... also, people have a tendency to pool their pills outside the study so everybody gets at least some active ingredient. Now studies are more often done comparing treatments for well studied diseases.
But for veganism there are no serious ethical issues of leaving these students in the control without treatment, and the number of people out of these groups who would have converted or reduced otherwise isn't known, and we can't extrapolate from anything else because we don't have good data on that, so in this case I think carnap is right.
A control group is important. Hell, even without the lecture a control group would be valuable to compare to the efficacy of other interventions on similar populations without controls because we'd have some idea of how many would have gone vegan otherwise.
The lecture a vs lecture b would have some value, but only comparative value. If you're certainly going to give a lecture, it'll tell you which kind... but maybe a lecture isn't the best outreach approach period. We'd be able to determine that with controls which would let us compare lectures, leaflets, videos, etc.
For example, with controls:
Study on lectures: A, B, and control
Study on leaflets: A, B, and control
Study on internet videos, A, B, and control
Only nine groups.
And if the population studied was very similar, a mere seven groups would work (one control among all of them).
Now we can compare leaflets, lectures, and internet videos without more studies.
Otherwise, we would need:
Study on lectures: A vs B
Study on leaflets: A vs B
Study on lectures vs. leaflets: A vs B
Study on lectures vs. internet videos: A vs B
Study on leaflets vs. internet videos: A vs B
This requires ten groups. Just one control on that population could have saved a lot of research.
And the requirement for more study groups grows exponentially as you evaluate more strategies.
Controls seem like a waste of time, but they're very valuable.