Scientific Investigation

The closeness of a measured value to a standard or known value

The closeness of two or more measurements to each other

A sample from a larger group that accurately represents the characteristics of a larger population

Individuals all have the same probability of being selected and are chosen randomly e.g. using random co-ordinates for soil samples

selecting members of the population at regular intervals - every nth person usually used along a transect e.g. temp when climbing a hill

Dividing a population into subpopulations based on specific characteristics - must take a proportional sample (in ratio)

large enough to be representative of the whole population

a method that allows data to be collected the same way by different people at different times controlling variables

a line or route that we stop upon and take a measurement at regular intervals systematic sampling

using quadrats can be interrupted or continuous

a way of applying observations to a category

dominant abundant frequent occasional rare

categorisation is subjective no numbers = no statistics can be calculated possibility of incorrect identification

square frame placed on top of vegetation random/systematic sampling count number of singular or different species counting can be subjective an inaccurate

like an open frame but divided into squares random/systematic sampling used for calculating % cover - 100 squares

T-shaped frame 10 long pins, plants that are hit by the pins are identified and counted useful for tall plants and uneven ground may damage vegetation

Place net on river bed, agitate sediment, allow organisms to flow into the net net must be downstream used to study freshwater invertebrates force of kicks may vary organism may be damaged

Net is directly connected to the site of disturbance, agitate sediment inside the square net must be downstream used to study freshwater invertebrates unable to use if riverbed is uneven

Provide an ideal habitat for the organism you want to count, wait for organism to colonise inaccurate as only some of the population will colonise it

Dig hole, insert container (top must be ground level), cover top with slate propped on pebbles, return, count and identify monitors terrestrial animals that live on ground surface animals may crawl out/eat each other if preservation fluid is used it may attract/repel specific organisms

Sweep net in figure of 8, set amount of times captures organisms that live on/in vegetation some may die when caught organisms can fly out

Beat trees/vegetation and catch fallout some organisms may not be dislodged some species may fly away difficult to standardise strength of beatin

Used to catch flying organisms identify, count, release may escape before counting different species are attracted to different wavelengths of light some don’t fly in rainy conditions

Collect soil/litter sample, place in container and turn on light (heat source), organisms move away from the light and fall through the grid into the collecting pot heat may kill organism some organisms may be too large for the grid some species are not repelled by light/heat