Unit 3: KA2 - Experimentation Flashcards
Define the term ‘reliability’
Refers to whether a procedure yields consistent values each time it is repeated or replicated.
Define the term ‘validity’
variables are controlled, so that any measured effect is likely to be due to the independent variable.
Define the term ‘accuracy’
A measure of how close the data sets are to the true value.
Define the term ‘precision’
Measured values are close to each other.
How are pilot studies used?
to help plan procedures, assess validity and check techniques.
What are the advantages of pilot studies?
- They allow the evaluation and modification of experimental design.
- can ensure an appropriate range of values for the independent variable.
- Establishment of number of repeat measurements required for representative value
Describe the types of variables.
- Dependent: Factor that changes as a result of the independent variable changing
- Independent: Factor being changed in a n investigation
- Confounding: Due to complexities of biological systems, other variables besides the independent variable may affect the dependent variable.
Describe the two categories that dependent and independent variables fall under.
Discrete: Distinct group
Continuous: Can be measured
Describe an experiment in terms of variables.
Experiments involve the manipulation of the independent variable by the investigator.
What is the experimental treatment group compared to?
A control group.
What is the term for an experiment which uses multiple independent variables
Multifactorial
Compare Simple and multifactorial experiments
Simple: - Easier to control confounding variables
- good for lab base studies
- simple protocols
- findings may not be applicable to a wider setting
Multifactorial: - Difficult to control confounding variables
- Can look at how different systems interact
- Complex protocol
- Useful for human/animal studies
Why may investigators use existing groups?
So there is no truly independent variable
Describe an observational study.
Features existing groups, so the independent variable is not directly controlled by the investigator, for ethical or logistical reasons.
Describe the advantage and disadvantage of observational studies
- Good at detecting correlation
- Since no direct hypothesis is tested, less useful at determining causation
What must be done with confounding variables in an investigation?
Must be held constant if possible, or at least monitored, so their effect on the results can be accounted for in the analysis.
What experimental design can be used to counteract confounding variables that cannot be easily controlled, and how does it work?
- Randomised block design
- Groups can be distributed in such a way that any confounding variable is likely to be the same across the treatment and control groups.
Why are controls used?
For comparison with the results of treatment group
Describe the types of controls.
Negative: Provides results in the absence of treatment
Positive: Treatment added to check that the system can detect a positive result when it occurs.
Define the term ‘Causation’.
Causation exists if the changes in the values of the independent variable are known to cause changes to the value of the dependent variable.
Define the term ‘placebo’.
Placebos can be included as a treatment without the presence of the independent variable being investigated
Define the term ‘placebo effect’.
Measurable changes in the dependent variable as a result of the patient’s expectations, rather than changes in the independent variable
Define the term ‘in vivo’
Refers to experimentation using a whole, living organism
Define the term ‘in vitro’
Refers to the technique of performing a given procedure in a controlled environment outside of a living organism.
