Experiments Design Flashcards
What is inductive reasoning?
The process of inferring a general law or principle from observation of a particular instance
Also know as bottom up reasoning
What is deductive reasoning?
Inference by reasoning from a general principle to a particular situation
Also know as top down logic
What is the scientific method cycle?
Question
Hypothesis
Experiment
Analyse data
Draw conclusions
Impact of data
What are the four obstacles to experiment design?
Perfectly definite change and does nothing else influence the result
Biological variability
Chance - experimental errors
Bias - in experimenter and design
Why is pairing important?
Change X can be difficult without changing Y and Z
But we can induce change Y and Z in another (paired) animal and show no change
Why might it be that vaccinated animals still die from the disease being tested?
Vaccine not prepared properly
Not vaccinated properly
Animals may have an inherent immunologic defect
Why might non-vaccinated animal live with disease being tested?
Animal could have acquired immunity
Passive immunity from mothers milk
Animals could be strong and healthy
Odd genetic makeup / defective receptor
How do you avoid the odd unreliable results that go against the hypothesis?
Use statistical analysis
Can prove that the different results would be expected by chance
What does randomised mean?
Subjects are assigned to either treatment or control groups in a random fashion
What is a double blind study?
Subjects aren’t aware of the treatment they’re receiving and neither are the investigators
What is a single blind study?
Subjects are aware of they’re treatment but the experimenter is
Potential for bias
What is a placebo controlled study?
A false treatment is necessary to measure the proportion of any observed effect accountable to the placebo effect
What is a cross over?
Subjects are swapped over from treatment to control groups
This assumes that the effects of the drug are completely reversible
What is a randomised block design?
Subjects are matched for
-age
- sex
- weight
- stage of life
What way can you control variability if results?
Randomised block design
