3.2 Experimental Design Flashcards
What are pilots studies and what do they do?
They are small, preliminary studies which aim to investigate whether crucial components of a main study will be feasible.
What are some advantages of pilot studies?
Plan Procedures
Access Vadility
Check tequniques
Evaluation and modification of experimental design
What is a Variable?
Any factor that can be controlled or changed or measured in an experiment
What is a dependent variable?
The variable being measured in a scientific experiment
What is an independent variable?
The thing changed in a scientific experiment.
What is continuous variation?
Take on an infinite number of values
What is discrete variation?
Have a finite range of values
What is the difference between simple and multifunctional experiments?
Multifunctional is more than one variable
An observational study is?
When the independent variable is not directly controlled by the investigator for ethical or logistical reasons.
What are observational studies good for?
Detecting correlation
Why would randomised block design be used?
In cases where confounding variables cannot be easily controlled.
What is a positive control?
A treatment that is included to check that the system can detect a positive result when it occurs.
What is a negative control?
Provides results in the absence of a treatment.
What is a placebo?
Something that can be included as a treatment without the presence of the independent variable being investigated
What is a placebo effect?
A measurable change in the dependent variable as a result of a patient’s expectations, rather than changes in the independent variable.
What is in vitro?
The technique of performing a given procedure in a controlled environment outside of a living organism.
What is in vivo?
Refers to experimentation using a whole, living organism.
A representative sample should….
..share the same the same mean and the same degree of variation about the mean as the population as a whole
What is random sampling?
Members of the population have an equal chance of being selected.
What is systematic sampling?
Members of a population are selected at regular intervals
What is stratified sampling?
The population is divided into categories that are then sampled proportionally.
What counts as qualitative data?
It is subjective and descriptive
What counts as quantatitive data?
It can be measured objectively, usually with numerical value
What is ranked data?
Numerical values are replaced by their rank from lowest to highest
Correlation is an ______ but does not imply _____
Correlation is an association and does not imply 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
A positive correlation exists when…
…when an increase in one variable is accompanied by an increase in the other variable
A negative correlation exists when…
…when an increase in one variable is accompanied by a decrease in the other variable
What is the entire scientific cycle?
Hypothesis, experimental design, gathering and recording, analysis of data, evaluation of results, conclusion
What is the null hypothesis?
Essentially the ‘no change position’ where you state there is no relationship between two variables
What is the alternative hypothesis and when is it used?
It is the opposite of the null hypothesis and is used when the null is disproven and rejected
Scientific ideas only become accepted when?
They have been checked independently
What are the three techniques used in animal studies to ensure ethically correctness
Replace, reduce and refine
In human studies, what things must be put in place ?
Informed consent, the right to withdraw data at any time and confidentiality
Background information should be?
Clear, relevant and unambigious.
Statistical tests are used to?
Determine whether the differences between the means are likely or unlikely to have occurred by chance.
What do error bars do?
Indicate the variability of data around the mean.
