types of sampling Flashcards
what is sampling?
measuring a small number of organisms in an area to estimate the total number of organisms in an area
what can sampling measure?
particular characteristics of an organism
what is meant by the abundance of an organism
the number of individuals of a species present in an area
what is random sampling
selecting individuals by chance
how may random sampling be carried out?
using a random number generator to select coordinates
what is non random sampling?
the sample is non chosen at random
what are the 3 main types of non random sampling?
- opportunistic
- stratified
- systematic
what is opportunistic sampling?
using organisms that are readily available (may not represent the whole population)
what is stratified sampling?
population is divided into strata based on characteristics - random sample is taken which is proportionate to the population
what is systematic sampling
different areas with clear change in an overall habitat are identified and then sampled
what is a line transect?
tape measure placed along single line through an ecosystem - plants touching the line at each interval are recorded
what is a belt transect?
place quadrats along a line and measure what is in each
what is sampling bias
where the selection process may be accidentally or deliberately biased
how can sampling bias be reduced?
by using a random sample
what is chance
where selected organisms may not, by chance, be representative of the whole population
