Full disclosure in research studies is sometimes considered problematic due to "Howthorne Effect".

Actulaly, as far as i know ,  a kinds of techniques can be used in some of research studies such as :

1). Covert data collection or Concealment.

2)  Deception either by withholding or giving false information.

Using such techniques depend of the type of the study , intevention used etc. However, these are still argumantetive and controversal. Some still agree that these can not be morally justified as it will not yield to "Truley Informed Consent".

Others who agree with these techniques say that it is OK to use them but if the study hold Minimial risk ( that are faced by the daily activity or normal procedure or tests) , don't invade privacy and promise to inform all the respondants at the end of the trial about all the information that was withhold or hiddens.

The only thing that is agreed on worldwide that Covert data collection, concealment or deception should be used, if advisalble by the ethical regulatory body, as the least resort.

many thanks Hedaya for the comprehensive answer 

thank you Mohammad for the contribution .. this is might be applied on the patients' adherence for example! so they might adhere more with the oral drug while they're enrolled into a clinical trial just because they know they are observed by the researcher!

Thank you Abdulqadir for your complement.

Mohammed , do you mean by the "Best Clinical Care"-->  the level of evidence?!! Hierarchy of evidence ?!! i did not understand ....

i am doing a hand hygiene study, on the same floor/hospital unit, first the control group, then the intervention group to a void contamination between groups, Also i am not doing direct observation, rather the alchol dispenser automatically count and submit each time the patient uses the dispenser. Direct observation of hand hygiene would cause the hawtharne effect. Hope this help.

I have a question to Mr. saed ... How will you minimize contamination of the results during the "Cross Over" period!? Some researchers would discard the infection rates during the first month of cross over , others might think of pausing the data collection during this period as well.

Mr. Mohammad, clinical trials are considered at the top level of evidence , assumed to be the most strongest that's why practice can be changed based on these levels.

Many steps have been taken to avoid other individuals use of the automated dispensers, 1) a red label on the dispenser saying, study material for patient use only with large font print, 2) staff has been educated about the study and not using the dispensers, 3) the dispensers are at the over bed table in the patient zone, 4) patients are advised about the study and that it is for their use only and not family members, 5) we still ask patient at exit survey, if any other individuals have used it or not and who?. The study is a pilot study, we are still learning from it. we discussed that possibility and implemented many other techniques to avoid that, still it is a limitation.

Here the turn over is extremely high on the unit, patients leave the floor in 2 days or less, We paused for 2 weeks between the control and the intervention group. One of the criteria for enrollment is not to have been a part of the control group, esp. for readmission.We only encountered 2 patients so far.

Great questions and comments, Feels like I am being quizzed. :(

Hahaha Mr Said ... Well this is the beauty of this website ...sharing the experience :)) 

Tnx for your comprehensive reply .... 

thank you everyone for the valuable contributions 

o how can you avoid the Hawthorne Effect?

As you’ve no doubt gathered by now, the problem with the Hawthorne Effect is that the gains are only short-term, so the obvious solution is to ensure that you’re monitoring performance frequently to ensure that any changes have legs.  This is relatively easy to do if you’re driving the change project as a salaried member of staff.  If you’re a consultant however it becomes a bit trickier.

If you follow these tips however you should be ok.

Tip 1 – Make sure you take a long-term approach.  You’re measuring how changes to process impact productivity, so the obvious step is to extend the timeline of the project to request that changes are maintained over a longer period of time.  Make sure that remuneration is framed in those terms.

Tip 2 – Be discreet in your observations.  It is reasonably well known that our behaviours are not always normal when we are being observed.  Some employees might want to try their best to make themselves appear good, whilst others will slacken off to create a low benchmark level.

Tip 3 – Communicate clearly the WIIFM.  Whilst it is still probable that behaviour might change, the process will be much more realistic if you communicate clearly from the beginning why you are doing this, and more importantly What’s In It For Me.  If employees think you are trying to be more efficient in order to lay off staff then it seems unlikely you’ll get a true reflection of how people work.  The same is true if people think you will just be asking them to work harder for no extra money.  If you can communicate how this will benefit them however it will show through in your results.

These three tips should help you to overcome the Hawthorne Effect and ensure that your process improvement efforts are both accurate and effective.

(Ref:Adi Gaskell : http://www.peterborner.com/2012/03/07/how-to-overcome-the-hawthorne-effect/)

very helpful tips John .. many thanks

Interesting question.  Most times, in randomized trials, the control group is the insurance that the Hawthorne effect is equivalent in both groups - assuming the intervention and control group are treated the same in every way possible.   Blinding, when feasible, the study subject and the study staff helps.  However, even when the Hawthorne effect is present, in well done trials it should occur equally in the intervention and control group.