#3 Investigating Populations - Sampling Flashcards
What is sampling used for?
to measure biodiversity of a habitat or the abundance of species
What is it impossible to count?
all of the organisms of a species
What do the samples need to be representative of?
the whole habitat / ecosystem (repeats)
What do you use sample data for?
to extrapolate to estimate the total number of individuals in the habitat / ecosystem
Random Sampling - What do you avoid?
avoid bias
Random Sampling - What do you divide sampling area into?
a grid
Random Sampling - What do you use a random number generator for?
to pick coordinates
Plants -
Mobile Animals -
Flying insects
Plants - Quadrats
Mobile animals - traps
Flying insects - sweep nets
Do the sample size need to be small or large?
large - and need lots of repeats
What should you sample at?
different times of day / year, weather conditions
What do you standardise?
sampling methods
What do you avoid capturing?
the same individuals twice
What do you calculate?
the mean
What do you use?
a statistical test
In systematic sampling, what are samples taken at?
fixed intervals
In systematic sampling, what does it measure?
a change in the enviroment
In opportunistic sampling, who are sample sites chosen by?
investigator - samples will be biased
it is also easy and fast to do
Stratified sampling - What is the survey area divided into?
groups
Stratified sampling - How is each area surveyed?
separately e.g. 5% pond, 20% wood land, etc.
in proportion to its coverage of total area
