key science skills

• Independent variable

  The variable manipulated by experimenter and is assumed to have a direct effect on the DV
• Dependent variable

  The variable that is measured or observed
• Extraneous variable

  Any variable that is not the independent variable but may cause an unwanted effect on the dependent variable. eg. previous flavours in mouth, order effects, soft drink experiences
• Control variable

  Variables other than the independent variable that a researcher holds constant (controls) in an investigation to ensure the changes in the dependent variable are solely due to changes in the independent variable. eg. same type of drink given
• Control group

  Group of participants who receive no experimental treatment
• Experimental group

  Group that is exposed to a manipulated independent variable
• Research method

  A controlled experiment was chosen for this investigation because two variables are being tested in a controlled environment, which is the effect of the IV on the DV while aiming to control other variables. This method allows the researcher to draw conclusions of specific variables.
• Operationalised variable

  A variable specifically defined and measured within the context of a controlled experiment. DV – perceived taste (asking participants to rate the taste from 1-10) IV – smell and vision (manipulating whether they experience the drink primarily through smelling it or seeing it.
• Between subjects design

  An experimental research method where individuals are divided into different groups and complete only one experimental condition. The strengths of this design is that it is less time consuming and does not create order effects. Limitations are individual differences may affect results.
• Within groups design

  An experimental design in which participants complete every experimental condition and the same participants are in both the control and experimental group
• A within-group design was chosen for this experiment as less people are needed and it ensures the results are more likely due to the manipulation of the IV and not individual differences. The same year 7 students will be in both the experimental and control group. They will taste drinks while being able to see and smell and after, they will not be able to see and smell. However, a limitation to this experimental design is that it may create order effects.
• Convenience sampling

  Sampling readily available members of population. This sampling technique was chosen because people that the experimenter already have access to are chosen, which makes it time efficient. However, a limitation to this sampling method is that it is likely to produce an unrepresentative sample, making it harder for researchers to generalise results to population
• Random sampling

  Any sampling technique that uses a procedure to ensure every member of a population has the same chance of being selected. A strength for this sampling method is that it reduces experimental bias and a limitation is it may not create an entirely representative sample if sample is small.
• Allocation

  Random allocation is when every member of the sample has an equal chance of being in the control or experimental group. In my experiment, the allocation involves the participant being exposed to both conditions of the independent variables, the experimental and control group.
• Ethical considerations relevant


  • Voluntary participation
  • Withdrawal rights
  • Debriefing
  • Confidentiality
• Reliability

  Refers to how consistent or dependable the results of an experiment are. The similar result amongst the participants demonstrates the reliability of experiment.
• Validity

  Refers to how accurately the experiment measures what it intends to measure
• Internal validity

  Refers to whether the experiment accurately measures what it intends to measure within its controlled environment. Eg. Internal validity would be ensuring that the manipulation of smell or vision is the primary factor influencing participant’s taste perception, rather than other variables.
• External validity

  Refers to the extent to which the findings of the experiment can be generalised to other populations. Eg. If the results from the year 7 class can be applied to other age groups.
• What is Voluntary participation

  Principle that ensures there is no pressure put on participant to partake in experiment
• What is Withdrawal rights

  Right of participants to be able to discontinue their involvement anytime without penalty
• What is Debriefing

  ensures that participant leave understanding the experimental aims results and conclusions
• Confidentiality refers to privacy, protection, and security of participant’s personal information and the anonymity of individual’s results.