Unit 3.2b Flashcards
What is a variable?
Any factor that can be controlled, changed, or measured in an experiment
What is an independent variable?
The variable that is changed in a scientific experiment
What is the dependent variable?
The variable measured in a scientific experiment
What is the continuous variable?
Variables with infinite numbers of values
-length, concentration, wavelength
What is the discrete variable?
Variables with a finite range of values
-colour
What is a simple experiment?
One with only 1 independent variable
What is a multifactoral experiment?
Am experiment with many independent variables
What’s an advantage of a simple experiment?
The control of laboratory conditions allows them to be conducted more easily, even in the field
What is the disadvantage of simple experiments?
The findings may not be applicable to a wider range of settings
Why can’t observational studies be used for determining causation?
There is no true correlation
What is an observational study?
Study where the independent variable is not directly controlled by the investigator
What are confounding variables?
Variables which cannot be altered
Age, gender etc
How are confounding variables controlled?
By using randomised block design
What is a positive control?
A treatment included that checks that the system can detect a positive result when it occurs
What is a negative result?
Provides a result in the absence of a treatment
What is a placebo?
It’s a treatment without the presence of the independent variable being investigated
What is the placebo effect?
It’s a measurable change in the dependent variable as a result of the patients expectation rather then a change in the independent variable
What is a benefit of a placebo?
If someone’s ill taking a placebo releases endorphins
Why do researches use placebo?
To see if the drug they are trialling is actually having an effect
What is in Vivo?
Experimentation using a whole living organism
What is in Vitro?
Performing a given procedure in a controlled environment outside of a living organism
What’s an advantage of in vitro?
Better control of the experiment and any confounding variables
What’s a disadvantage of in vitro?
Not possible for most biological studies
What’s an advantage of in Vivo?
Better idea of what is going on inside the cell or organism
What’s a disadvantage of in Vivo?
Living organisms show great variability which can’t really be controlled
