Worldwide, there were more than 1.56 billion people who used Facebook daily in March 2019.
There were “only” half as many daily active users in 2014, but typical adults in the U. already spent 40 minutes daily on Facebook, much of that using News Feed.
Is it ethical to randomly assign some people in an outbreak area to a control group that doesn’t receive the vaccine?
In this case, health workers used a procedure called ring vaccination, in which first appearance of the disease in a village led to vaccination of all direct contacts of the initially afflicted individual, then to all contacts of this group.
For control groups, posts were randomly removed from News Feed streams.
The researchers then assessed whether these treatments were associated with changes in use of positive and negative words in subsequent posts sent by the subjects of the experiment.The new drug might be effective, but there might be little or no measurable difference in outcome because the subjects treated with the new drug were in worse condition to start with.Besides randomization of treatments to subjects and comparison to a control group, clinical trials are usually also “double blinded”, meaning that both volunteer subjects and researchers don’t know the treatment that each subject received until after the results are recorded and analyzed.My main examples in Chapter 4 of TCTB were two randomized, controlled trials of the effects of smoking marijuana on pain in human subjects.The methodology of these experiments was typical of a wide variety of clinical trials in medicine, from tests of new drugs to comparisons of different surgical procedures and much more.In Chapter 4 of Tools for Critical Thinking in Biology (TCTB), I described experiments as the gold standard for research, in keeping with common practice.The dictionary definition of experiment is quite general, e.g., “a scientific procedure undertaken to make a discovery, test a hypothesis, or demonstrate a known fact.” I used a much more specific definition in explaining why experiments are the gold standard for research – experiments as randomized, controlled trials.If there were such bias, we couldn’t confidently attribute any difference in outcome to the difference in treatments that the subjects received because the treatments would be confounded with the source of bias.For an example of unconscious bias, suppose researchers assigned the first 25 volunteers to the new drug and the next 25 to the standard psoriasis treatment.But experiments may not be feasible for some questions; for example, questions about processes that occur at large spatial or temporal scales.Why do more species of birds live in the tropics than at higher latitudes?