Control Groups, Observational Studies & Evaluting Experimental Designs Flashcards
Why are control groups used?
They enable comparison of the experimnetal groups results with controls results so that the experimental design can be shown to be valid.
Whats a negative control?
A control that provides data for what happens in the absence of a treatment in order to check false positive results are not occuring. If the negative control gives unexpected results, it is likely that a confoundning variable is not being fully controlled.
What is a positive control?
A control that provides data to prove the experimental design can detect changes in the dependent variable in order to check false results are not occuring. The positive control is expected to have an effect on the dependent variable to compare the experimental group to.
What is an observational study?
A study that uses groups that already exist to carry out a study. e.g. when studying the effects of smoking an observational study would be to use a group of people who already smoke.
What is a positive and negative correlation?
Positive - as one variable increases, the other variable increases too.
Negative - when one variable increases, the other variable decreases.
What does ‘in vitro’ and ‘in vivo’ mean?
In vivo - Describes studies involving living organisms.
In vitro - Describes studies using isolated compomemts or organisms.
What are advantages and disadvantages of in vitro studies?
Advantages - simpler, easier to control confounding variables, can demonstrate correlation and causation (changing one variable results in the other varibale changing too).
Disadvantages - Difficult to extend the results to the whole organism or to different species.
What are the advantages and disadvantages of in vivo studies?
Advantages - Provides data for the whole organism and allows the study of complex interactions.
Disadvantages - Expensive and time consuming, ethical concerns, and difficult to prove correlation and causation.
