The concept of publication bias is based on an assumption that researchers tend to report a study if the result is 'positive' and tend to leave it unreported if the result is 'negative.' Performance bias means systematic differences in the care provided, apart from the intervention being evaluated. Selection bias means that there are systematic differences in the compared groups at the baseline. Attrition bias means high or divergent drop-out proportions. Detection bias means systematic differences in outcome assessment. Posted 8/06 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.