week 7 reading Flashcards
what is an experimental unit?
the physical entity which can be assigned, at random, to a treatment e.g. individual animals, plots, quadrats
what is a treatment?
any kind of manipulation applied to experimental units
what is a treatment group?
A group of experimental units that all receive the same treatment
what is a control group?
experimental units in a control group receive either no treatment or some kind of standard treatment
what is a factor?
a collection of related treatments and controls
what is replication?
assigning several experimental units to the same treatment or combination of treatments
what is pseudoreplication?
an artificial increase in the sample size (and hence degrees of freedom) caused by using non-independent data
what is confounding variation?
occurs when there are one or more other sources of variation that work in parallel to the factor we are investigating and make it hard, or impossible, to unambiguously attribute any effects we see to a single cause
what is noise?
variation that is unrelated to the factor we are investigating but adds variability to the results so that it is harder to see, and detect statistically, any effect of that factor
techniques for dealing with confounding variation and noise:
randomisation
blocking
experimental control
additional treatments
what is ‘between group’ variation?
Variation due to the effect of experimental treatments or control groups
what are the assumptions of ANOVA?
independence
measurement scale
equal variance
normality
