Biases

Placebo effect

This is a psychological phenomenon where a patient experiences an improvement in symptoms due to the belief that they are receiving treatment. This can inadvertently distort results of clinical trials where a 'placebo group' believes they are receiving the treatment under study.

Hawthorne effect

This refers to the alteration of people's behaviour when they are aware they are being observed. This awareness can cause individuals to work harder, skewing the results of studies, particularly those involving human performance.

Measurement bias

Occurs when data or information is not accurately recorded in a research study. This can stem from errors in data collection, inconsistent measurement tools, or subjective interpretation of data, leading to skewed and unreliable results.

Publication bias

This is the tendency for researchers and editors to handle the reporting of experimental results that are positive (i.e., showing a significant finding) differently from results that are negative (i.e., supporting the null hypothesis) or inconclusive, leading to a misleading bias in the overall published literature.

Observer/experimenter bias

Is when the person conducting the research allows their expectations or beliefs to influence the results of the experiment. This can lead to distorted data, as the researcher may subconsciously favour results that confirm their own preconceptions or hypotheses.

Reporting bias

Is a type of bias where researchers selectively report or omit information based on the outcome of the research or personal beliefs, which can distort the findings and undermine the integrity of the study.

Sampling bias

Is when the selection of participants for a research study isn't representative of the whole population. The skewed sample could lead to a misrepresentation of the data and flawed conclusions.

Recall bias

This occurs when the participants in a research study may not remember previous events or experiences accurately or they may subconsciously alter their memories. This can lead to skewed data and ultimately impact the credibility of the research results.

Selection bias

Occurs when the method of selecting participants or groups for a study produces an outcome that is not representative of the total population. For instance, if the sample group is not randomised or certain groups are excluded, it could produce skewed or incomplete results.

Confirmation bias

This is the tendency to favour, seek out, interpret, and remember information in a way that confirms one's pre-existing beliefs or hypotheses, whilst giving disproportionately less consideration to alternative possibilities. This bias can lead to flawed conclusions as it may prevent researchers from accurately assessing all relevant data in a neutral manner.

In qualitative research, bias can be prevalent in the form of interviewer bias where the researcher's beliefs or opinions may sway the direction of the interview or even influence how participant responses are interpreted. Another form of bias is social desirability bias, where participants might respond to questions in a way that presents them in a more favourable light rather than revealing their true thoughts or feelings.