The “no difference” or “no association” hypothesis, to be tested, usually by means of a significance test, against an alternative hypothesis.

Examples:

The species composition (or species body size or species phenology) is the same in different habitat types.

The species composition is the same in natural areas and areas disturbed by anthropogenic activities.

The species composition is the same in different geographical areas.

The species composition is the same in different seasons;

Grassland species composition is the same in farmed and not-farmed fields (or in inland and coastal dune habitats or….).

Grassland plants have same type of leaves in cultured and not cultured fields (or inland and coastal dune habitats or….).

The diversity of cat mantles is the same comparing blocks of buildings in the same town or different towns

Colour of flowers is the same in grasslands, dunes, woodlands, coastal chaparral….

The release of a by-product of human activity -chemical or physical- that causes harm to human health and/or the natural environment; contamination causing adverse effects.

Group of the individual organisms of the same species living in a particular area (habitat).

The number of species present at a particular place and time. No assumptions are made about the relative abundance of these species. It is not possible to enumerate all species in a community then it become necessary to distinguish between numerical species richness, which is defined as the number of species per specified number of individuals or biomass, and species density, which is the number of species per specified collection area.

A game in which players assume the roles of characters in a fictional setting. Players take responsibility for acting out these roles within a narrative, either through literal acting or through a process of structured decision-making or character development.

The degree to which a sample might differ from the population.

The process of selecting some part of a population to observe and to estimate something of interest about the whole population (ex: the abundance of a rare or endangered species in the population might be estimated by the pattern of detections from a sample of sites taken in the study region). These methods assume that each member of the population has a known non-zero probability of being selected (probability sampling methods). They include simple random sampling, systematic sampling, and stratified sampling. Sampling error, which is the degree to which a sample might differ from the population, could be calculated and results are reported plus or minus the sampling error.

The levels or sizes at which particular ecological entities or processes are considered. One distinction that is often made is between local, regional and biogeographic scales.

Facts obtained by making observations and measurements.

Educated guesses that attempt to explain scientific observations or scientific laws. It is the first step in the scientific method.