Aresearcher can't randomly assign offenders to groups, and they have to find volunteers for the control group that does not get the treatment. the volunteers were lower risk than the treatment group. name the internal validity threat:

You could solve them by trying something new that everyone can agree on or make a decision too.

Texas’ gulf coastal plains are the western extension of the coastal plain extending from the atlantic ocean to beyond the rio grande. its characteristic rolling to hilly surface covered with a heavy growth of pine and hardwoods extends into east texas. in the increasingly arid west, however, its forests become secondary in nature, consisting largely of post oaks and, farther west, prairies and brushlands.