What is Scientific bias?

Scientific bias is a systematic error.  It gives an association that is not true.

In nutrition there are 5 main types of bias which can be found within studies:

Measurement bias - Poorly measured or improperly measured tests. Such as machines not been correctly calibrated for example.

Interviewer Bias - The outcome of the results is shaped by the belief of the interviewer.  For example, should the interviewer feel there would be a benefit from the test, they will impress upon the subject their own bias.

Selection bias - Proper randomisation of subjects is not achieved.

Social acceptability bias - Survey respondents will answer questions in a manner which will be viewed favourably by others.  Some people change their habits to encourage a better view of themselves.  If there was an exercise questionnaire,  subjects may be inclined to increase their exercise for better opinions of themselves.

Recall bias - Inaccurate recollections by study participants.  It is not always easy to remember.  IF subjects were asked to write down what the had eaten earlier in the day, they might well not remember.

Bias Mind map.