why the sell-off?, page-47

As well as geology/economics/finance/management, I also did a postgrad dip in diseases at London School of Tropical Medicine which included a unit on biostats, hence a limited knowledge of the procedures. The following is from:

http://home.vicnet.net.au/~mecfs/general/dbpct.html

Randomised, double blind, placebo-controlled trials

A "randomised" study is one in which usually two possible drugs are given to the participants - one is the active drug which is believed to hold some promise as an effective treatment, the other is a "placebo" - a drug which has no expected treatment value and which looks, tastes, feels as close as possible to identical to the active drug.

The randomisation is a code (usually generated by computer) which allocates each individual by chance to receive either the active drug or the placebo. This aspect of the trial designed tends to make up for any variation in the nature of the illness affecting the patients enrolled (such as differences in severity or duration of symptoms), and therefore allows successful statistical evaluation of any difference response rate between the two groups.

The "double-blind" is the procedure in the study design which makes every attempt to ensure that neither the patient nor the researchers are aware which drug (active or placebo) each subject is receiving.

The "blind" is very important in this type of research as it ensures that neither the patients nor the researcher can have any direct effect on the outcome of the treatment due to factors such as the effect of believing that one is receiving the active drug which in itself may produce some benefit.

Similarly, the researchers may inadvertently or otherwise affect the outcome it he is aware of which treatment a patient is receiving.

Every patient is monitored in an identical fashion.

At the completion of the trial, that is when every patient has completed the treatment course and completed the follow-up, a code is broken which details which patients have received the active and which patients the placebo treatment. An analysis is then made of the data which has already been collected for each patient, as to whether a larger number of patients receiving the active drug than the placebo showed a response to the treatment.

Patients who enrol at the beginning of a large trial may have to wait a long period until all the following patients have completed the trial and the code is broken to find out which treatment they have been given.

This type of trial design is the only accepted way of establishing a new treatment into medical practice.

Hope this helps

G