reliability, accuracy, validity Flashcards
reliability
the degree to which a measurement or test gives consistent results each time the experiment is performed. A reliable experiment will have similar results each time the experiment is repeated.
how to determine degree of reliablity
A reliable experiment will have similar results each time the experiment is repeated. The level of reliability can be reduced by error
repeatability- aspect of reliability
the original investigator repeats the experiment and obtains similar results using the same method and equipment. If something has a high degree of repeatability, it will have reliable results.
reproducibility- aspect of reliability
when a new investigator repeats the experiment and obtains similar results using the same method and procedure
precision- aspect of reliability
the measure of how close experimental results are to each other (the ‘correct’ value is irrelevant)
random error
an error that has variable size and direction
random errors can be caused by…
environmental conditions, experimental factors and intrinsic variability
intrinsic variability
the inherent differences between samples eg. different organisms of the same species
how random errors can be reduced
increasing the number of trials, increasing sample size, removing outliers from results
sample size
the number of units in a population to be studied
accuracy
a measure of how close the experimental results are to the true value. It can be reduced by systemic errors and is limited by the resolution of measuring instruments.
systemic errors
a repeated, reproducible error that is consistently in the same direction.
systemic errors can be reduced by…
calibrating instruments, using instruments correctly, reducing interaction with the environment
resolution of instruments
how well a measuring instrument can distinguish between two similar values
validity
how well an experiment procedure tests the aim and hypothesis of an experiment.
