Definition:Convenience Sample

Definition
Let $P$ be a population in the physical universe.

Let $S \subsetneq P$ be a sample.

Suppose that data about some individuals in $P$ are more easily accessible than data about others.

Then $S$ is a convenience sample iff the primary criterion for the construction of $S$ is the higher accessibility of data of certain individuals in $P$ over others.

That is, the objects in $S$ are the ones conveniently at hand.