(7) Pilot Studies, Single/double Blind Procedures

• Pilot Studies :

  • allow researcher to test investigation procedure with a small group of participants before the investigation begins
  • small scale version of an investigation that takes place before the real investigation is completed
  • aim is to check that procedures, materials measuring scales (equipment) works
  • also allows the researcher to make changes or modifications if necessary
• pilot studies are not just restricted to experimental studies
• pilot studies are important when using self report methods such as questionnaires or interviews as it is helpful to try out questions in advance and remove or reword those that are ambiguous or confusing - lead to bias
• in observational studies pilot studies :

  • provide a way of checking coding systems before the real investigation is undertaken
  • Important to train observers prior to conducting research
• through pilot studies :

  • researcher can identify potential issues + use them to modify their design and procedure
  • will save time and money in the long run
  • ensures mistakes hopefully won't be made in the 'real' study
• the aim of the pilot study to identify areas that need improving before research commences
• a pilot study involves a practice run of the study to asses the validity and design of the study
• a pilot study takes place before research formally begins
• the data from pilot studies can be referred to in the design or discussion sections of reports but not in the research data analysis
• pilot study can be used to improve internal validity of the research
• pilot studies help with both reliability and validity of research
• Pilot Studies - Reliability in research :

  • reliability refers to the consistency of results
  • can help reliability indirectly
  • pilot studies can help rectify issues to improve the methodology (standardised procedures) - increases ow reliable the study is
  • pilot studies allow reliability to be checked - study can be done again
• Pilot Studies - Validity in Research :

  • validity refers to the accuracy of research - measuring what we set out to measure
  • pilot studies help identify errors in research - design decisions that need to be changed/ features of the study that need altering
  • pilot studies help improve the validity of the study - more accurate and making sure you’re measuring what you set out to measure
  • researcher may rewrite instructions to a task
• blinding or masking refers to withholding information regarding the group assignments from the participants, the researcher, or both during the study
• information that could be blinded/ masked from the participants is who is in the treatment group and who is in the control group
• a blinded study prevents the participants from knowing about their treatment to avoid bias in the research
• in a blinded study, any information that can influence the subjects is withheld until the completion of the research
• blinding can be imposed on any participant in an experiment, including researcher, data collectors, evaluators, technicians and data analysts
• good blinding can eliminate experimental biases arising from :

  • the subject's expectations
  • observer bias
  • confirmation bias
  • researcher bias
  • observer's effect on the participants
  • other biases that occur in a research test
• Single Blind Study :

  • patients do not know which study group they are in
  • the researcher does know which study group the participant is in
  • usually withhold information given to participants that may create any expectations prior to the experiment
  • participants only told the full aims at the end of the study
  • this attempts to control for the confounding effects of demand characteristics
• Double Blind Trial :

  • neither the patients nor the researcher know which study group the participants are in
  • a third party will conduct the investigation without knowing its main purpose - to avoid bias (contracter)
  • important useage in drug trials
  • the third party is independent of the investigation : does not know which condition the participant is in - reduces experimenter bias (expectations cannot influence participant behaviour)
• blinding trials present ethical issues as participants are not always told the full aims of experiments prior to taking part - could be argued is a form of deception
• participants not knowing whether they are in the experimental or control condition could cause them distress