Nonliving factors that influences the life and activities of an organism (ex: light, temperature, water, pH…).

The opposite to the null hypothesis; it considers that the observations are the result of a real effect and not due only to change (null hypothesis).

A statistical method developed by R. A. Fischer used to test whether two or more sample means have been obtained from populations with the same sample mean. When only two samples are involved, the Student’s t-test can also be used. The analysis of variance is however more general in the sense that it can be used to test simultaneously three of more samples.