Scientific investigation Flashcards
Define the term accuracy
- the closeness of a measured value to a standard or known value
Define the term precision
- the closeness of two or more measurements to each other
Define the term representative sample
- a sample that represents the whole population
Define hypothesis
- a statement that you test through research and experiments
Define null hypothesis
- type of statistical hypothesis that proposes that no significance exists in a set of given observations
Define random sampling
- type of probability sampling in which the researcher randomly selects a subset of participants from a population
Define systematic sampling
- a probability sampling method where researchers select members of the population at regular intervals
Define stratified sampling
- involves the division of a population into smaller subgroups
What should you consider when deciding the number of samples in a study
- size of population
-variability in population
What is a standardised sampling method and why is it important
- method that allows data to be collected in exactly the same way by different people at different times
- give clear methods and equipment
- control any variables
Why is timing important in experimental design
- time of day, night
- if organisms have a life cycle e.g hibernation
- migration patterns
What is a belt transect
- sample along a route at regular intervals
What is an abundance scale and why are they useful
- way of applying what you see to a category
- doesn’t require counting
What are the limitations of an abundance scale
- subjective
- no statistical tests
- relies on human observations ( room for error )
What are the 3 types of quadrats
- open frame
- grid
-point
What is kick sampling and what are the limitations
- hold a net downstream and disturb the bed of water and collect sediment in net
- different efforts put into kicks
-some organisms can swim
What is suber sampling and what are the limitations
- same as kick sampling but with a frame on where you kick
- ground could be uneven
What is colonisation media and what are the limitations
- provide a habitat for the organism that you’re counting
- organism isn’t attracted to it
- don’t have total population size
What is a pitfall trap and what are the limitations
- dig a hole and place a cup in the ground and insects will fall into it
- some could escape
- organisms could eat one another
What is a sweep net and what are the limitations
- sweep a net in a figure of 8 to catch things such as moths in a large field
- organism could be harmed
- organism could escape
What is a beating tray and what are the limitations
- beat a huge net underneath a tree and invertebrates will fall and land on the tray
- organisms can fly
- organisms could remain in the tree
What is a light trap and what are the limitations
- using uv, white light to catch moths
- could escape before counting
- different species of moth are attracted to different wavelengths of light
What is a tullgren funnel and what are the limitations
- collect a soil sample, and it filters down the tunnel and organisms are caught in a dish at the bottom
- heat may harm the organisms
- some organisms may be too big to filter all the way down
What is earthworm extraction and what are the limitations
- add an irritant, water or stamp on the ground to attract the worms upwards
- irritant could kill the worms
-worms could move sideways instead of upwards
