3.d. Experimental design (27) Flashcards
(28 cards)
What is an independent variable?
The variable that is changed in an experiment.
What is a dependent variable?
The variable that is measured in an experiment.
What can independent and dependent variable be?
discrete or continuous.
What is discrete and how can data be shown?
Distinct and unrelated value and plotted using a bar graph.
What is continuous and how can data be shown?
Range of values and plotted using a line graph.
What do experiments involve the manipulation of?
Independent variable.
What are experiment treatment groups compared to?
Control group
What can experiments be?
simple or multifactorial
What is simple?
There is only one independent variable.
What is multifactorial?
There is multiple independent variables.
What are the advantages of simple?
Conducted more easily than in field.
What are the disadvantages of simple?
Results not applicable to wider setting.
What are observational studies good at detecting?
Good at detecting correlation but not causation as is does not directly test the hypothesis.
What are confounding variables?
A factor that affects the dependent variable that is not the independent variable.
What should confounding variables be held at?
A constant or monitored so their effect can be accounted for in the result.
What should you do if the confounding variables cannot be controlled?
Use a randomised block design.
What are control groups used for?
For comparison with the results of treatment groups and shows any effects are as a result of the treatment.
What are the two types of controls?
Positive and negative
What is negative control?
Provides results in the absence of a treatment.
What is a positive control?
To check is the system can detect a positive results when it occurs.
What are placebos?
Treatment without the presence of the independent variable being investigated.
What is the placebo effect?
A measurable change in the dependent variable as a result of patient expectations rather than changes in the independent variable.
What is in vitro studies?
Refers to the technique of performing a given procedure in a controlled environment outside of a living organism.
What are examples of in vitro studies?
- Cells growing in a culture medium
- Proteins in solution
- Purifies organelles
